The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Charles O. Rock - One of the best experts on this subject based on the ideXlab platform.
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DesT Coordinates the Expression of Anaerobic and Aerobic Pathways for Unsaturated Fatty Acid Biosynthesis in Pseudomonas aeruginosa
Journal of Bacteriology, 2009Co-Authors: Chitra Subramanian, Charles O. Rock, Yongmei ZhangAbstract:The fabA and fabB genes are responsible for anaerobic Unsaturated Fatty Acid formation in Pseudomonas aeruginosa. Expression of the fabAB operon was repressed by exogenous Unsaturated Fatty Acids, and DNA sequences upstream of the translational start site were used to affinity purify DesT. The single protein interaction with the fabAB promoter detected in wild-type cell extracts was absent in the desT deletion strain, as was the repression of fabAB expression by Unsaturated Fatty Acids. Thus, DesT senses the overall composition of the acyl-coenzyme A pool to coordinate the expression of the operons for the anaerobic (fabAB) and aerobic (desCB) pathways for Unsaturated Fatty Acid synthesis.
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a new mechanism for anaerobic Unsaturated Fatty Acid formation in streptococcus pneumoniae
Journal of Biological Chemistry, 2002Co-Authors: Hedia Marrakchi, Charles O. Rock, Keumhwa ChoiAbstract:The anaerobic pathway for Unsaturated Fatty Acid synthesis was established in the 1960s in Escherichia coli. The double bond is introduced into the growing acyl chain by FabA, an enzyme capable of both the dehydration of β-hydroxydecanoyl-acyl carrier protein (ACP) to trans-2-decenoyl-ACP, and the isomerization of trans-2 to cis-3-decenoyl-ACP. However, there are a number of anaerobic bacteria whose genomes do not contain a fabA homolog, although these organisms nonetheless produce Unsaturated Fatty Acids. We cloned and biochemically characterized a new enzyme in type II Fatty Acid synthesis from Streptococcus pneumoniae that carries out the isomerization of trans-2-decenoyl-ACP tocis-3-decenoyl-ACP, but is not capable of catalyzing the dehydration of β-hydroxy intermediates. This tetrameric enzyme, designated FabM, has no similarity to FabA, but rather is a member of the hydratase/isomerase superfamily. Thus, the branch point in the biosynthesis of Unsaturated Fatty Acids in S. pneumoniae occurs following the formation oftrans-2-decenoyl-ACP, in contrast to E. coliwhere the branch point takes place after the formation of β-hydroxydecanoyl-ACP.
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the fabr yijc transcription factor regulates Unsaturated Fatty Acid biosynthesis in escherichia coli
Journal of Biological Chemistry, 2002Co-Authors: Yongmei Zhang, Charles O. Rock, Hedia MarrakchiAbstract:Unsaturated Fatty Acid biosynthesis is a vital facet of Escherichia coli physiology and requires the expression of two genes, fabA and fabB, in the type II Fatty Acid synthase system. This study links the FabR (YijC) transcription factor to the regulation of Unsaturated Fatty Acid content through the regulation of fabB gene expression. The yijC (fabR) gene was deleted by replacement with a selectable cassette, and the resulting strains (fabR::kan) possessed significantly elevated levels of Unsaturated Fatty Acids, particularly cis-vaccenate, in their membrane phospholipids. The altered Fatty Acid composition was observed in the fabR::kan fabF1 double mutant pinpointing fabB as the condensing enzyme responsible for the increased cis-vaccenate production. The fabR::kan strains had 4- to 8-fold higher levels of fabB and a 2- to 3-fold increase in fabA transcripts as judged by Northern blotting, Affymetrix array analysis, and real-time PCR. FabR did not regulate the enzymes of Fatty Acid beta-oxidation. The elevated level of fabB mRNA was reflected by higher condensing enzyme activity in fabR::kan fabF1 double mutants. Thus, FabR functions as a repressor that potently controls the expression of the fabB gene, which in turn, modulates the physical properties of the membrane by altering the level of Unsaturated Fatty Acid production.
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Increased Unsaturated Fatty Acid production associated with a suppressor of the fabA6(Ts) mutation in Escherichia coli.
Journal of Bacteriology, 1996Co-Authors: Charles O. Rock, Jiu-tsair Tsay, Richard J. Heath, Suzanne JackowskiAbstract:Plasmids that corrected the temperature-sensitive Unsaturated Fatty Acid auxotrophy of strain M6 [fabA6 (Ts)] were isolated from an Escherichia coli genomic library. Subcloning and physical mapping localized the new gene (called sfa for suppressor of fabA) at 1,070 kb on the E. coli chromosome. DNA sequencing revealed the presence of a 227-bp open reading frame which directed the synthesis of a peptide of approximately 8 kDa, which correlated with the correction of the fabA6(Ts) phenotype. However, the sfa gene was an allele-specific suppressor since plasmids harboring the sfa gene corrected the growth phenotype of fabA6(Ts) mutants but did not correct the growth of fabA2(Ts) or fabB15(Ts) Unsaturated Fatty Acid auxotrophs. Overexpression of the sfa gene in fabA6(Ts) mutants restored Unsaturated Fatty Acid content at 42 degrees C, and overexpression in wild-type cells resulted in a substantial increase in the Unsaturated Fatty Acid content of the membrane. Thus, the suppression of the fabA6(Ts) mutation by sfa was attributed to its ability to increase the biosynthesis of Unsaturated Fatty Acids.
Xianlin Han - One of the best experts on this subject based on the ideXlab platform.
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identification and quantitation of Unsaturated Fatty Acid isomers by electrospray ionization tandem mass spectrometry a shotgun lipidomics approach
Analytical Chemistry, 2011Co-Authors: Kui Yang, Zhongdan Zhao, Richard W Gross, Xianlin HanAbstract:Identification and quantification of Unsaturated Fatty Acid (FA) isomers in a biological system are significant in the study of lipid metabolism and catabolism, membrane biophysics, and pathogenesis of diseases but are challenging in lipidomics. We developed a novel approach for identification and quantitation of Unsaturated FA isomers by exploiting two facts: (1) Unsaturated FA anions yield fragment ion(s) from loss of CO2 or H2O from the anions upon collision-induced dissociation; and (2) the fragment ions yielded from discrete FA isomers have distinct profiles of the fragment ion intensity vs. collision conditions. These distinct profiles likely result from the differential interactions of the negative charge of the fragment ion with the electron clouds of the double bonds due to their different distances in discrete FA isomers. The novel approach was also extended to analyze the double bond isomers of FA chains present in phospholipids by multistage tandem mass spectrometry. Collectively, we developed...
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identification and quantitation of Unsaturated Fatty Acid isomers by electrospray ionization tandem mass spectrometry a shotgun lipidomics approach
Analytical Chemistry, 2011Co-Authors: Kui Yang, Zhongdan Zhao, Richard W Gross, Xianlin HanAbstract:Identification and quantification of Unsaturated Fatty Acid (FA) isomers in a biological system are significant in the study of lipid metabolism and catabolism, membrane biophysics, and pathogenesis of diseases but are challenging in lipidomics. We developed a novel approach for identification and quantitation of Unsaturated FA isomers by exploiting two facts: (1) Unsaturated FA anions yield fragment ion(s) from loss of CO(2) or H(2)O from the anions upon collision-induced dissociation; and (2) the fragment ions yielded from discrete FA isomers have distinct profiles of the fragment ion intensity vs. collision conditions. These distinct profiles likely result from the differential interactions of the negative charge of the fragment ion with the electron clouds of the double bonds due to their different distances in discrete FA isomers. The novel approach was also extended to analyze the double bond isomers of FA chains present in phospholipids by multistage tandem mass spectrometry. Collectively, we developed a new approach for identification and quantification of the double bond isomers of endogenous FA species or FA chains present in intact phospholipid species. We believe that this approach should further advance the lipidomic power for identification of the biochemical mechanisms underlying metabolic diseases.
Vytas A. Bankaitis - One of the best experts on this subject based on the ideXlab platform.
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Unsaturated Fatty Acid‐induced non‐canonical autophagy: unusual? or unappreciated?
The EMBO Journal, 2015Co-Authors: Vytas A. BankaitisAbstract:The breakdown of cellular components via autophagy is crucial for cellular homeostasis. In this issue of The EMBO Journal , Niso‐Santano et al (2015) report the important observation that feeding cells with saturated or Unsaturated Fatty Acids triggers mechanistically distinct autophagic responses. Feeding cells saturated Fatty Acid induced the canonical, BECN1/PI3K‐dependent autophagy pathway. Conversely, the Unsaturated Fatty Acid oleate triggered autophagic responses that were independent of the BECN1/PI3K complex, but that required a functional Golgi system.
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Unsaturated Fatty Acid‐induced non‐canonical autophagy: unusual? or unappreciated?
The EMBO journal, 2015Co-Authors: Vytas A. BankaitisAbstract:The breakdown of cellular components via autophagy is crucial for cellular homeostasis. In this issue of The EMBO Journal , Niso‐Santano et al (2015) report the important observation that feeding cells with saturated or Unsaturated Fatty Acids triggers mechanistically distinct autophagic responses. Feeding cells saturated Fatty Acid induced the canonical, BECN1/PI3K‐dependent autophagy pathway. Conversely, the Unsaturated Fatty Acid oleate triggered autophagic responses that were independent of the BECN1/PI3K complex, but that required a functional Golgi system.
Kui Yang - One of the best experts on this subject based on the ideXlab platform.
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identification and quantitation of Unsaturated Fatty Acid isomers by electrospray ionization tandem mass spectrometry a shotgun lipidomics approach
Analytical Chemistry, 2011Co-Authors: Kui Yang, Zhongdan Zhao, Richard W Gross, Xianlin HanAbstract:Identification and quantification of Unsaturated Fatty Acid (FA) isomers in a biological system are significant in the study of lipid metabolism and catabolism, membrane biophysics, and pathogenesis of diseases but are challenging in lipidomics. We developed a novel approach for identification and quantitation of Unsaturated FA isomers by exploiting two facts: (1) Unsaturated FA anions yield fragment ion(s) from loss of CO2 or H2O from the anions upon collision-induced dissociation; and (2) the fragment ions yielded from discrete FA isomers have distinct profiles of the fragment ion intensity vs. collision conditions. These distinct profiles likely result from the differential interactions of the negative charge of the fragment ion with the electron clouds of the double bonds due to their different distances in discrete FA isomers. The novel approach was also extended to analyze the double bond isomers of FA chains present in phospholipids by multistage tandem mass spectrometry. Collectively, we developed...
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identification and quantitation of Unsaturated Fatty Acid isomers by electrospray ionization tandem mass spectrometry a shotgun lipidomics approach
Analytical Chemistry, 2011Co-Authors: Kui Yang, Zhongdan Zhao, Richard W Gross, Xianlin HanAbstract:Identification and quantification of Unsaturated Fatty Acid (FA) isomers in a biological system are significant in the study of lipid metabolism and catabolism, membrane biophysics, and pathogenesis of diseases but are challenging in lipidomics. We developed a novel approach for identification and quantitation of Unsaturated FA isomers by exploiting two facts: (1) Unsaturated FA anions yield fragment ion(s) from loss of CO(2) or H(2)O from the anions upon collision-induced dissociation; and (2) the fragment ions yielded from discrete FA isomers have distinct profiles of the fragment ion intensity vs. collision conditions. These distinct profiles likely result from the differential interactions of the negative charge of the fragment ion with the electron clouds of the double bonds due to their different distances in discrete FA isomers. The novel approach was also extended to analyze the double bond isomers of FA chains present in phospholipids by multistage tandem mass spectrometry. Collectively, we developed a new approach for identification and quantification of the double bond isomers of endogenous FA species or FA chains present in intact phospholipid species. We believe that this approach should further advance the lipidomic power for identification of the biochemical mechanisms underlying metabolic diseases.
Yongmei Zhang - One of the best experts on this subject based on the ideXlab platform.
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DesT Coordinates the Expression of Anaerobic and Aerobic Pathways for Unsaturated Fatty Acid Biosynthesis in Pseudomonas aeruginosa
Journal of Bacteriology, 2009Co-Authors: Chitra Subramanian, Charles O. Rock, Yongmei ZhangAbstract:The fabA and fabB genes are responsible for anaerobic Unsaturated Fatty Acid formation in Pseudomonas aeruginosa. Expression of the fabAB operon was repressed by exogenous Unsaturated Fatty Acids, and DNA sequences upstream of the translational start site were used to affinity purify DesT. The single protein interaction with the fabAB promoter detected in wild-type cell extracts was absent in the desT deletion strain, as was the repression of fabAB expression by Unsaturated Fatty Acids. Thus, DesT senses the overall composition of the acyl-coenzyme A pool to coordinate the expression of the operons for the anaerobic (fabAB) and aerobic (desCB) pathways for Unsaturated Fatty Acid synthesis.
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the fabr yijc transcription factor regulates Unsaturated Fatty Acid biosynthesis in escherichia coli
Journal of Biological Chemistry, 2002Co-Authors: Yongmei Zhang, Charles O. Rock, Hedia MarrakchiAbstract:Unsaturated Fatty Acid biosynthesis is a vital facet of Escherichia coli physiology and requires the expression of two genes, fabA and fabB, in the type II Fatty Acid synthase system. This study links the FabR (YijC) transcription factor to the regulation of Unsaturated Fatty Acid content through the regulation of fabB gene expression. The yijC (fabR) gene was deleted by replacement with a selectable cassette, and the resulting strains (fabR::kan) possessed significantly elevated levels of Unsaturated Fatty Acids, particularly cis-vaccenate, in their membrane phospholipids. The altered Fatty Acid composition was observed in the fabR::kan fabF1 double mutant pinpointing fabB as the condensing enzyme responsible for the increased cis-vaccenate production. The fabR::kan strains had 4- to 8-fold higher levels of fabB and a 2- to 3-fold increase in fabA transcripts as judged by Northern blotting, Affymetrix array analysis, and real-time PCR. FabR did not regulate the enzymes of Fatty Acid beta-oxidation. The elevated level of fabB mRNA was reflected by higher condensing enzyme activity in fabR::kan fabF1 double mutants. Thus, FabR functions as a repressor that potently controls the expression of the fabB gene, which in turn, modulates the physical properties of the membrane by altering the level of Unsaturated Fatty Acid production.
