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Hiroyuki Arata - One of the best experts on this subject based on the ideXlab platform.
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Structure of the Membrane-intrinsic Nitric Oxide Reductase from Roseobacter Denitrificans
Biochemistry, 2016Co-Authors: Allister Crow, Yuji Matsuda, Hiroyuki Arata, Arthur OubrieAbstract:Membrane-intrinsic nitric oxide reductases (NORs) are key components of bacterial denitrification pathways with a close evolutionary relationship to the cytochrome oxidase (COX) complex found in aerobic respiratory chains. A key distinction between COX and NOR is the identity of the metal directly opposite heme b3 within the active site. In NOR, this metal is iron (FeB), whereas in COX, it is copper (CuB). The purified NOR of Roseobacter Denitrificans contains copper and has modest oxidase activity, raising the possibility that a COX-like active site might have independently arisen within the context of a NOR-like protein scaffold. Here we present the crystal structure of the Roseobacter Denitrificans NorBC complex and anomalous scattering experiments probing the identity of each metal center. Our results refute the hypothesis that copper occupies the active site and instead reveal a new metal center in the small subunit not seen in any other NOR or COX.
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structural characterization of a binuclear center of a cu containing no reductase homologue from Roseobacter Denitrificans epr and resonance raman studies
Biochimica et Biophysica Acta, 2004Co-Authors: Yuji Matsuda, Takeshi Uchida, Hiroshi Hori, Teizo Kitagawa, Hiroyuki ArataAbstract:Aerobic phototrophic bacterium Roseobacter Denitrificans has a nitric oxide reductase (NOR) homologue with cytochrome c oxidase (CcO) activity. It is composed of two subunits that are homologous with NorC and NorB, and contains heme c, heme b, and copper in a 1:2:1 stoichiometry. This enzyme has virtually no NOR activity. Electron paramagnetic resonance (EPR) spectra of the air-oxidized enzyme showed signals of two low-spin hemes at 15 K. The high-spin heme species having relatively low signal intensity indicated that major part of heme b3 is EPR-silent due to an antiferromagnetic coupling to an adjacent CuB forming a Fe–Cu binuclear center. Resonance Raman (RR) spectrum of the oxidized enzyme suggested that heme b3 is six-coordinate high-spin species and the other hemes are six-coordinate low-spin species. The RR spectrum of the reduced enzyme showed that all the ferrous hemes are six-coordinate low-spin species. ν(Fe–CO) and ν(C–O) stretching modes were observed at 523 and 1969 cm−1, respectively, for CO-bound enzyme. In spite of the similarity to NOR in the primary structure, the frequency of ν(Fe–CO) mode is close to those of aa3- and bo3-type oxidases rather than that of NOR.
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Nitric oxide-reductase homologue that contains a copper atom and has cytochrome c-oxidase activity from an aerobic phototrophic bacterium Roseobacter Denitrificans.
Journal of biochemistry, 2002Co-Authors: Yuji Matsuda, Kei-ichiro Inamori, Tsukasa Osaki, Akane Eguchi, Azusa Watanabe, Shun-ichiro Kawabata, Koh Iba, Hiroyuki ArataAbstract:A cytochrome cb-type enzyme with cytochrome c-oxidase activity was purified from an aerobic phototrophic bacterium Roseobacter Denitrificans. The enzyme was solubilized with sucrose monodecanoate from the membranes of R. Denitrificans grown aerobically under light conditions, and purified to electrophoretic homogeneity. Absorption spectra of the purified enzyme showed peaks at 410 nm and 530 nm in the oxidized state, and peaks at 420, 522, and 551 nm and a shoulder at around 560 nm in the reduced state. The enzyme is composed of two subunits with apparent molecular weights on SDS-PAGE of 37,000 and 18,000, the latter positive to heme staining. The protein contains heme c, heme b, and copper in a 1:2:1 stoichiometry. The spectral properties indicated that the heme c and one heme b are in low-spin states, while the other heme b is in a high-spin state. The base sequences of the genes and the deduced amino acid sequences are similar to those of known NorB and NorC subunits of nitric oxide reductases from other bacterial species. The enzyme is similar to nitric oxide reductase, but differs in that it contains copper. Virtually no nitric oxide reductase activity was detected in the purified enzyme.
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Some properties and occurrence of cytochrome c-552 in the aerobic photosynthetic bacterium Roseobacter Denitrificans
Archives of microbiology, 1993Co-Authors: Ken-ichiro Takamiya, Hiroyuki Arata, Yuzo Shioi, Masakazu Morita, Minoru Shimizu, Michio DoiAbstract:Characteristics and occurrence of cytochrome c-552 from an aerobic photosynthetic bacterium, Roseobacter Denitrificans, were described.
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purification and properties of trimethylamine n oxide reductase from aerobic photosynthetic bacterium Roseobacter Denitrificans
Journal of Biochemistry, 1992Co-Authors: Hiroyuki Arata, Minoru Shimizu, Ken-ichiro TakamiyaAbstract:Trimethylamine N-oxide (TMAO) reductase was purified from an aerobic photosynthetic bacterium Roseobacter Denitrificans. The enzyme was purified from cell-free extract by ammonium sulfate fractionation, DEAE ion exchange chromatography, hydrophobic chromatography, and gel filtration. The purified enzyme was composed of two identical subunits with molecular weight of 90,000, as identified by SDS-polyacrylamide gel electrophoresis, containing heme c and a molybdenum cofactor. The molecular weight of the native enzyme determined by gel filtration was 172,000. The midpoint redox potential of heme c was +200 mV at pH 7.5. Absorption maxima appeared at 418,524, and 554 nm in the reduced state and 410 nm in the oxidized state. The enzyme reduced TMAO, nicotine acid N-oxide, picoline N-oxide, hydroxylamine, and bromate, but not dimethyl sulfoxide, methionine sulfoxide, chlorate, nitrate, or thiosulfate. Cytochrome c2 served as a direct electron donor. It probably catalyzes the electron transfer from cytochrome b-c1 complex to TMAO reductase. Cytochrome c552, another soluble low-molecular-weight cytochrome of this bacterium, also donated electrons directly to TMAO reductase.
Nianzhi Jiao - One of the best experts on this subject based on the ideXlab platform.
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Complete genome sequence of the siphovirus Roseophage RDJLΦ 2 infecting Roseobacter Denitrificans OCh114
Marine genomics, 2015Co-Authors: Yantao Liang, Yongyu Zhang, Chao Zhou, Zhenghao Chen, Suping Yang, Changzhou Yan, Nianzhi JiaoAbstract:RDJLΦ2, a lytic phage that infects the marine bacterium Roseobacter Denitrificans OCh114, one of the model organisms of the Roseobacter clade, was isolated. Here we report the overall genome architecture of RDJLΦ2. Morphological and genome analysis revealed that RDJLΦ2 is a siphovirus with a 63.5 kb genome that contains 76 putative gene products.
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host responses of a marine bacterium Roseobacter Denitrificans och114 to phage infection
Archives of Microbiology, 2012Co-Authors: Yongyu Zhang, Fan Zhang, Jun Yang, Nianzhi JiaoAbstract:RDJLΦ1 is a marine siphophage infecting Roseobacter Denitrificans OCh114. In this study, host responses of R. Denitrificans OCh114 to phage infection were investigated through in situ real-time atomic force microscopy (AFM) and proteomics approaches. As seen from the AFM observations, during phage infection processes, depression areas appeared on the host cell surface in a few minutes after infection and expanded in both diameter and depth over time and finally led to the collapse of host cells within 30 min. The two-dimensional polyacrylamide gel electrophoresis revealed significant changes in the proteomic composition of the host cells during infection. The expression of 91 proteins, including some involved in DNA transcription regulation and substrate transportation, was changed with at least twofold up- or downregulation as compared to the control without phage infection. This observed rapid lysis of host cells and the great changes in protein expression caused by phage infection added more perspectives to the documented important roles of viruses in mediating carbon cycling in the ocean.
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Complete genome sequence of a marine roseophage provides evidence into the evolution of gene transfer agents in alphaproteobacteria.
Virology journal, 2011Co-Authors: Sijun Huang, Yongyu Zhang, Feng Chen, Nianzhi JiaoAbstract:Roseophage RDJLΦ1 is a siphovirus isolated from South China Sea on Roseobacter Denitrificans OCh114. Its virion encapsulates 62.7 kb genome that encodes 87 gene products. RDJLΦ1 shares similar genome organization and gene content with the marine bacteriophage ΦJL001 and Pseudomonas phages YuA and M6, which are different from those of typical λ- or Mu-like phages. Four hallmark genes (ORFs 81 to 84) of RDJLΦ1 were highly homologous to RcGTA-like genes 12 to 15. The largest gene (ORF 84) was predicted to encode a tail fibre protein that could be involved in host recognition. Extended phylogenetic and comparative genomic analyses based on 77 RcGTA-like element-containing bacterial genomes revealed that RcGTA-like genes 12 to 15 together appear to be a conserved modular element that could also be found in some phage or prophage genomes. Our study suggests that RcGTA-like genes-containing phages and prophages and complete RcGTAs possibly descended from a same prophage ancestor that had diverged and then evolved vertically. The complete genome of RDJLΦ1 provides evidence into the hypothesis that extant RcGTA may be a prophage remnant.
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characterization of the photosynthetic apparatus and proteome of Roseobacter Denitrificans
Current Microbiology, 2010Co-Authors: Kai Tang, Rui Zong, Fan Zhang, Na Xiao, Nianzhi JiaoAbstract:The phototrophic capacity of aerobic anoxygenic phototrophic bacteria endows them with a selective advantage over other heterotrophic bacteria in the oligotrophic ocean. Here, we reported the phototrophic features and proteome of an aerobic phototrophic bacterium Roseobacter Denitrificans under starvation stress. The fluorescence induction and relaxation measurements suggested that the photosynthetic capacity in R. Denitrificans was preserved but was lower than in the photoautotrophic bacterium Rhodobacter sphaeroides. The existence of light-harvesting complexes (LH1 and LH2) and the reaction center (RC) in the native membrane were demonstrated through atomic force microscopy image analysis as direct evidence of their phototrophy. The homology-based LH1-RC complex structure was proposed in which RC was the Rb. sphaeroides homolog structure surrounded by the LH1. Moreover, the protein expression profiles of cells in the stationary phase under heterotrophic and mixotrophic conditions show that light enhanced or activated some proteins such as carbon monoxide dehydrogenase and NifU to cope with the low levels of amino acids and carbon sources under starvation conditions.
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Phage Resistance of a Marine Bacterium, Roseobacter Denitrificans OCh114, as Revealed by Comparative Proteomics
Current microbiology, 2010Co-Authors: Chunxiao Huang, Yongyu Zhang, Nianzhi JiaoAbstract:Roseobacter is a dominant lineage in the marine environment. This group of bacteria is diverse in terms of both their phylogenetic composition and their physiological potential. Roseobacter Denitrificans OCh114 is one of the most studied bacteria of the Roseobacter lineage. Recently, a lytic phage (RDJLΦ1) that infects this bacterium was isolated and a mutant strain (M1) of OCh114 that is resistant to RDJLΦ1 was also obtained. Here, we investigate the mechanisms supporting phage resistance of M1. Our results excluded the possibilities of several phage resistance mechanisms, including abortive infection, lysogeny, and the clustered regularly interspaced short palindromic repeats (CRISPRs) related mechanism. Adsorption kinetics assays revealed that adsorption inhibition might be a potential cause for the phage resistance of M1. Comparative proteomic analysis of M1 and OCh114 revealed significant changes in the membrane protein compliment of these bacteria. Five membrane proteins with important biological functions were significantly down-regulated in the phage-resistant M1. Meanwhile, several outer membrane porins with different modifications and an OmpA family domain protein were markedly up-regulated. We hypothesize that the down-regulated membrane proteins in M1 may serve as the potential phage receptors, whose absence prevented the adsorption of phage RDJLΦ1 to host cells and subsequent infection.
Ken-ichiro Takamiya - One of the best experts on this subject based on the ideXlab platform.
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expression of the puf operon in an aerobic photosynthetic bacterium Roseobacter Denitrificans
Plant and Cell Physiology, 1996Co-Authors: Kohji Nishimura, Yuzo Shioi, Hiroshi Shimada, Hiroyuki Ohta, Tatsuru Masuda, Ken-ichiro TakamiyaAbstract:The effects of oxygen and light on the expression of the puf operon were investigated in Roseobacter Denitrificans in a comparison with those in Rhodobacter sphaeroides. In darkness, the levels of the total puf mRNA in Ros. Denitrificans were about 1.3 times those in Rb. sphaeroides at low concentrations of oxygen, reflecting the accumulation of bacteriochlorophyll and carotenoids. The oxygen tension, up to 94% saturation of dissolved oxygen, did not affect the levels of the total puf transcripts in Ros. Denitrificans, whereas those in Rb. sphaeroides were reduced to 55% of the maximum level even at 50% saturation. Four puf-specific transcripts were detected: a 0.5-kb transcript was the most abundant; 1.2-kb and 1.9-kb transcripts accumulated at low levels; and a 3.5-kb transcript accumulated at very low levels under all conditions tested. The levels of the individual transcripts were barely affected by molecular oxygen. An S-1 nuclease protection assay revealed that the 0.5-kb transcript encoded the LHI-alpha and LHI-beta subunits (pufBA), the 1.2-kb transcript encoded puf-BA and part of pufL, and the 1.9-kb transcript encoded pufBAL and part of pufM. It was not clear whether the 3.5-kb transcript encoded the entire pufBALM and the gene for the polypeptide moiety of cytochrome c. The difference in levels between the 0.5-kb transcript and the other transcripts (1.2 kb, 1.9 kb, and 3.5 kb) was presumed to be due to the presence of several stem-loop structures at the 3' terminus of the 0.5-kb transcript which acted as terminators of transcription and, possibly, as protection against nucleolytic digestion. Light inhibited the expression of the puf operon in Ros. Denitrificans more effectively than that in Rb. sphaeroides. The insensitivity to oxygen, as well as the sensitivity to light, of the expression of the puf operon in Ros. Denitrificans, which was different from that in Rb. sphaeroides, seemed to represent a mode of adaptation that allowed the former cells to avoid photodynamic damage by light under highly aerobic conditions.
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Some properties and occurrence of cytochrome c-552 in the aerobic photosynthetic bacterium Roseobacter Denitrificans
Archives of microbiology, 1993Co-Authors: Ken-ichiro Takamiya, Hiroyuki Arata, Yuzo Shioi, Masakazu Morita, Minoru Shimizu, Michio DoiAbstract:Characteristics and occurrence of cytochrome c-552 from an aerobic photosynthetic bacterium, Roseobacter Denitrificans, were described.
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purification and properties of trimethylamine n oxide reductase from aerobic photosynthetic bacterium Roseobacter Denitrificans
Journal of Biochemistry, 1992Co-Authors: Hiroyuki Arata, Minoru Shimizu, Ken-ichiro TakamiyaAbstract:Trimethylamine N-oxide (TMAO) reductase was purified from an aerobic photosynthetic bacterium Roseobacter Denitrificans. The enzyme was purified from cell-free extract by ammonium sulfate fractionation, DEAE ion exchange chromatography, hydrophobic chromatography, and gel filtration. The purified enzyme was composed of two identical subunits with molecular weight of 90,000, as identified by SDS-polyacrylamide gel electrophoresis, containing heme c and a molybdenum cofactor. The molecular weight of the native enzyme determined by gel filtration was 172,000. The midpoint redox potential of heme c was +200 mV at pH 7.5. Absorption maxima appeared at 418,524, and 554 nm in the reduced state and 410 nm in the oxidized state. The enzyme reduced TMAO, nicotine acid N-oxide, picoline N-oxide, hydroxylamine, and bromate, but not dimethyl sulfoxide, methionine sulfoxide, chlorate, nitrate, or thiosulfate. Cytochrome c2 served as a direct electron donor. It probably catalyzes the electron transfer from cytochrome b-c1 complex to TMAO reductase. Cytochrome c552, another soluble low-molecular-weight cytochrome of this bacterium, also donated electrons directly to TMAO reductase.
Gerhart Drews - One of the best experts on this subject based on the ideXlab platform.
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the reaction center of Roseobacter Denitrificans primary structure of the h subunit and homology model of the hlm complex
1998Co-Authors: Stefan Michael Herter, Andreas Labahn, Christiane Kortluke, Oliver Hucke, Gerhart DrewsAbstract:Roseobacter (Rs.) Denitrificans belongs to the so-called aerobic photosynthetic bacteria. This type of bacteria is closely related to purple bacteria, but in contrast to these ‘true’ photosynthetic bacteria, they are not able to grow under anoxic conditions (1). Photosynthetic protein complexes and bacteriochlorophyll are only built under oxic conditions in these bacteria. Rs. Denitrificans is phylogenetically close to Rhodobacter (Rb.) capsulatus a true phototrophic purple bacterium (2). The puf operon encoding the protein subunits L, M, C of the reaction center (RC) and of light harvesting complex I (LHI) from Rs. Denitrificans were cloned and sequenced and show very high similarities to purple bacteria in either single sequences or the whole operon structure (3). Despite these similarities charge separation does not occur in the reaction center under anoxic conditions (4). The lack of photosynthetic activity was believed to be caused by the overreduction of the electron transfer system (1) and a higher midpoint redox potential of the primary acceptor (QA) of the RC in aerobic phototrophs compared to that of typical purple bacteria (5). For a better understanding of the charge separation in Rs. Denitrificans RC the M and L subunits of RC from Rs. Denitrificans were combined with the H-subunit from Rb. capsulatus in a Rb. capsulatus puf puc negative mutant (6). Charge recombination between the primary donor P3+ and Q A − was observed in the transconjugant indicating a correct assembly of L and M subunits but the transconjugant did not grow under anoxic conditions. In Rhodobacter sphaeroides it was shown that the H-subunit has an influence on electron transfer from QA to QB (7, 8). Since the H-subunit could be responsible for the differences between purple bacteria and aerobic phototrophs we cloned and sequenced the RC H-subunit from Rs. Denitrificans. To get informations about the interaction between the quinones and the surrounding protein matrix a model of the HLM-complex of the RC was calculated.
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structure of the puf operon of the obligately aerobic bacteriochlorophyll alpha containing bacterium Roseobacter Denitrificans och114 and its expression in a rhodobacter capsulatus puf puc deletion mutant
Journal of Bacteriology, 1997Co-Authors: Christiane Kortluke, Andreas Labahn, Klaus Breese, Nasser Gadon, Gerhart DrewsAbstract:Roseobacter Denitrificans (Erythrobacter species strain OCh114) synthesizes bacteriochlorophyll a (BChl) and the photosynthetic apparatus only in the presence of oxygen and is unable to carry out primary photosynthetic reactions and to grow photosynthetically under anoxic conditions. The puf operon of R. Denitrificans has the same five genes in the same order as in many photosynthetic bacteria, i.e., pufBALMC. PufC, the tetraheme subunit of the reaction center (RC), consists of 352 amino acids (Mr, 39,043); 20 and 34% of the total amino acids are identical to those of PufC of Chloroflexus aurantiacus and Rubrivivax gelatinosus, respectively. The N-terminal hydrophobic domain is probably responsible for anchoring the subunit in the membrane. Four heme-binding domains are homologous to those of PufC in several purple bacteria. Sequences similar to pufQ and pufX of Rhodobacter capsulatus were not detected on the chromosome of R. Denitrificans. The puf operon of R. Denitrificans was expressed in trans in Escherichia coli, and all gene products were synthesized. The Roseobacter puf operon was also expressed in R. capsulatus CK11, a puf puc double-deletion mutant. For the first time, an RC/light-harvesting complex I core complex was heterologously synthesized. The strongest expression of the R. Denitrificans puf operon was observed under the control of the R. capsulatus puf promoter, in the presence of pufQ and pufX and in the absence of pufC. Charge recombination between the primary donor P+ and the primary ubiquinone Q(A)- was observed in the transconjugant, showing that the M and L subunits of the RC were correctly assembled. The transconjugants did not grow photosynthetically under anoxic conditions.
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origin of the two carbonyl oxygens of bacteriochlorophyll a demonstration of two different pathways for the formation of ring e in rhodobacter sphaeroides and Roseobacter Denitrificans and a common hydratase mechanism for 3 acetyl group formation
FEBS Journal, 1996Co-Authors: Robert J Porra, Gerhart Drews, Wolfram Schafer, Nasr Gadon, Ingrid Katheder, Hugo ScheerAbstract:A respiring culture of Rhodobacter sphaeroides, grown in the dark under defined aerobic conditions, produced cells capable of immediately commencing adaptation to photosynthetic growth on exposure to light and further reduction of oxygen tension. Adaptation was complete after 12 h and the bacteriochlorophyll a content increased 10–20-fold. This adaptation was performed in the presence of either H218O or 18O2. The extracted bacteriochlorophyll a was examined by mass spectrometry to determine the origin of both the 3-acetyl and 131-oxo oxygen atoms: both were derived from water. The derivation of the 131-oxo group from water in R. sphaeroides indicates that the formation of isocyclic ring E from the 13-propionic acid methylester side chain of Mg2+-protoporphyrin IX mono-methylester is an anaerobic process involving a hydratase. This is very different to the situation in higher plants and green algae where the formation of isocyclic ring E is an aerobic process in which the 131-oxo group is derived from molecular oxygen via an oxygenase. In contrast to adapting R. sphaeroides cells, the 131-oxo group of bacteriochlorophyll a in growing cells of the obligate aerobic chemotrophic bacterium Roseobacter Denitrificans, was labelled by 18O2 and is, therefore, derived from molecular oxygen like in higher plants and green algae; however, the 3-acetyl group was not labelled by 18O2. Thus, while the 131-oxo group has different origins in R. sphaeroides and R. Denitrificans, the 3-acetyl group arises in both bacteria by enzymic hydration of the vinyl group of a chlorophyll a derivative.
Yongyu Zhang - One of the best experts on this subject based on the ideXlab platform.
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Complete genome sequence of the siphovirus Roseophage RDJLΦ 2 infecting Roseobacter Denitrificans OCh114
Marine genomics, 2015Co-Authors: Yantao Liang, Yongyu Zhang, Chao Zhou, Zhenghao Chen, Suping Yang, Changzhou Yan, Nianzhi JiaoAbstract:RDJLΦ2, a lytic phage that infects the marine bacterium Roseobacter Denitrificans OCh114, one of the model organisms of the Roseobacter clade, was isolated. Here we report the overall genome architecture of RDJLΦ2. Morphological and genome analysis revealed that RDJLΦ2 is a siphovirus with a 63.5 kb genome that contains 76 putative gene products.
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host responses of a marine bacterium Roseobacter Denitrificans och114 to phage infection
Archives of Microbiology, 2012Co-Authors: Yongyu Zhang, Fan Zhang, Jun Yang, Nianzhi JiaoAbstract:RDJLΦ1 is a marine siphophage infecting Roseobacter Denitrificans OCh114. In this study, host responses of R. Denitrificans OCh114 to phage infection were investigated through in situ real-time atomic force microscopy (AFM) and proteomics approaches. As seen from the AFM observations, during phage infection processes, depression areas appeared on the host cell surface in a few minutes after infection and expanded in both diameter and depth over time and finally led to the collapse of host cells within 30 min. The two-dimensional polyacrylamide gel electrophoresis revealed significant changes in the proteomic composition of the host cells during infection. The expression of 91 proteins, including some involved in DNA transcription regulation and substrate transportation, was changed with at least twofold up- or downregulation as compared to the control without phage infection. This observed rapid lysis of host cells and the great changes in protein expression caused by phage infection added more perspectives to the documented important roles of viruses in mediating carbon cycling in the ocean.
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Complete genome sequence of a marine roseophage provides evidence into the evolution of gene transfer agents in alphaproteobacteria.
Virology journal, 2011Co-Authors: Sijun Huang, Yongyu Zhang, Feng Chen, Nianzhi JiaoAbstract:Roseophage RDJLΦ1 is a siphovirus isolated from South China Sea on Roseobacter Denitrificans OCh114. Its virion encapsulates 62.7 kb genome that encodes 87 gene products. RDJLΦ1 shares similar genome organization and gene content with the marine bacteriophage ΦJL001 and Pseudomonas phages YuA and M6, which are different from those of typical λ- or Mu-like phages. Four hallmark genes (ORFs 81 to 84) of RDJLΦ1 were highly homologous to RcGTA-like genes 12 to 15. The largest gene (ORF 84) was predicted to encode a tail fibre protein that could be involved in host recognition. Extended phylogenetic and comparative genomic analyses based on 77 RcGTA-like element-containing bacterial genomes revealed that RcGTA-like genes 12 to 15 together appear to be a conserved modular element that could also be found in some phage or prophage genomes. Our study suggests that RcGTA-like genes-containing phages and prophages and complete RcGTAs possibly descended from a same prophage ancestor that had diverged and then evolved vertically. The complete genome of RDJLΦ1 provides evidence into the hypothesis that extant RcGTA may be a prophage remnant.
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Phage Resistance of a Marine Bacterium, Roseobacter Denitrificans OCh114, as Revealed by Comparative Proteomics
Current microbiology, 2010Co-Authors: Chunxiao Huang, Yongyu Zhang, Nianzhi JiaoAbstract:Roseobacter is a dominant lineage in the marine environment. This group of bacteria is diverse in terms of both their phylogenetic composition and their physiological potential. Roseobacter Denitrificans OCh114 is one of the most studied bacteria of the Roseobacter lineage. Recently, a lytic phage (RDJLΦ1) that infects this bacterium was isolated and a mutant strain (M1) of OCh114 that is resistant to RDJLΦ1 was also obtained. Here, we investigate the mechanisms supporting phage resistance of M1. Our results excluded the possibilities of several phage resistance mechanisms, including abortive infection, lysogeny, and the clustered regularly interspaced short palindromic repeats (CRISPRs) related mechanism. Adsorption kinetics assays revealed that adsorption inhibition might be a potential cause for the phage resistance of M1. Comparative proteomic analysis of M1 and OCh114 revealed significant changes in the membrane protein compliment of these bacteria. Five membrane proteins with important biological functions were significantly down-regulated in the phage-resistant M1. Meanwhile, several outer membrane porins with different modifications and an OmpA family domain protein were markedly up-regulated. We hypothesize that the down-regulated membrane proteins in M1 may serve as the potential phage receptors, whose absence prevented the adsorption of phage RDJLΦ1 to host cells and subsequent infection.
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Roseophage RDJLΦ1, Infecting the Aerobic Anoxygenic Phototrophic Bacterium Roseobacter Denitrificans OCh114
Applied and environmental microbiology, 2009Co-Authors: Yongyu Zhang, Nianzhi JiaoAbstract:A marine roseophage RDJL Phi1 lytically infecting Roseobacter Denitrificans OCh114 was isolated and characterized. RDJL Phi1 can package several host cellular proteins into its virions, and its DNA is refractory to several commonly used restriction enzymes. This paper presents the first report of a bacteriophage isolated from the aerobic anoxygenic phototrophic bacteria.
