The Experts below are selected from a list of 315003 Experts worldwide ranked by ideXlab platform
Jianwei Xiao - One of the best experts on this subject based on the ideXlab platform.
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pdm4 a pentatricopeptide repeat protein affects chloroplast gene expression and chloroplast development in arabidopsis thaliana
Frontiers in Plant Science, 2020Co-Authors: Jianwei Xiao, Xinwei Wang, Lirong Zhao, Yi Man, Li WangAbstract:Extensive studies have been carried out on chloroplast gene expression and chloroplast development; however, the regulatory mechanism is still largely unknown. Here, we characterized Pigment-Defective Mutant4 (PDM4), a P-type PPR protein localized in chloroplast. The pdm4 mutant showed seedling-lethal and albino phenotype under heterotrophic growth conditions. Transmission electron microscopic analysis revealed that thylakoid structure was totally disrupted in pdm4 mutant and eventually led to the breakdown of chloroplasts. The levels of several chloroplast- and Nuclear-Encoded Proteins are strongly reduced in pdm4 mutant. Besides, transcript profile analysis detected that, in pdm4 mutant, the expression of plastid-encoded RNA polymerase-dependent genes was markedly affected, and deviant chloroplast rRNA processing was also observed. In addition, we found that PDM4 functions in the splicing of group II introns and may also be involved in the assembly of the 50S ribosomal particle. Our results demonstrate that PDM4 plays an important role in chloroplast gene expression and chloroplast development in Arabidopsis.
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LTD is a protein required for sorting light-harvesting chlorophyll-binding Proteins to the chloroplast SRP pathway
Nature Communications, 2011Co-Authors: Min Ouyang, Wei Chi, Jianwei Xiao, Meijuan Zou, Fan Chen, Lixin ZhangAbstract:Higher plants require chloroplasts for essential functions in photosynthesis and other important physiological processes, such as sugar, lipid and amino-acid biosynthesis. Most chloroplast Proteins are Nuclear-Encoded Proteins that are synthesized in the cytosol as precursors, and imported into chloroplasts by protein translocases in the outer and inner chloroplast envelope. The imported chloroplast Proteins are then translocated into or across the thylakoid membrane by four distinct pathways. However, the mechanisms by which the imported Nuclear-Encoded Proteins are delivered to these pathways remain largely unknown. Here we show that an Arabidopsis ankyrin protein, LTD (mutation of which causes the light-harvesting chlorophyll-binding protein translocation defect), is localized in the chloroplast and using yeast two-hybrid screens demonstrate that LTD interacts with both Proteins from the signal recognition particle (SRP) pathway and the inner chloroplast envelope. Our study shows that LTD is essential for the import of light-harvesting chlorophyll-binding Proteins and subsequent routing of these Proteins to the chloroplast SRP-dependent pathway.
Kostas Tokatlidis - One of the best experts on this subject based on the ideXlab platform.
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The coiled coil‐helix‐coiled coil‐helix Proteins may be redox Proteins
FEBS Letters, 2009Co-Authors: Lucia Banci, Ivano Bertini, Simone Ciofi-baffoni, Kostas TokatlidisAbstract:A number of nuclear encoded Proteins are imported in to the intermembrane space of mitochondria where they adopt a coiled coil-helix-coiled coil-helix (CHCH) fold. Two disulfide bonds formed by twin CX3C or CX9C motifs stabilize this fold. Some of these Proteins are also characterized at their N-termini by the presence of two additional cysteine residues which can perform oxidoreductase or metallochaperone functions or both. This fold represents the most ‘minimal’ oxidoreductase domain described so far.
Johannes M. Herrmann - One of the best experts on this subject based on the ideXlab platform.
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Cytosolic Events in the Biogenesis of Mitochondrial Proteins.
Trends in biochemical sciences, 2020Co-Authors: Yury S. Bykov, Doron Rapaport, Johannes M. Herrmann, Maya SchuldinerAbstract:While targeting of Proteins synthesized in the cytosol to any organelle is complex, mitochondria present the most challenging of destinations. First, import of Nuclear-Encoded Proteins needs to be balanced with production of mitochondrial-encoded ones. Moreover, as mitochondria are divided into distinct subdomains, their Proteins harbor a number of different targeting signals and biophysical properties. While translocation into the mitochondrial membranes has been well studied, the cytosolic steps of protein import remain poorly understood. Here, we review current knowledge on mRNA and protein targeting to mitochondria, as well as recent advances in our understanding of the cellular programs that respond to accumulation of mitochondrial precursor Proteins in the cytosol, thus linking defects in targeting-capacity to signaling.
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Biogenesis of Mitochondrial Proteins
Advances in Experimental Medicine and Biology, 2012Co-Authors: Johannes M. Herrmann, Sebastian Longen, Daniel Weckbecker, Matthieu DepuydtAbstract:Depending on the organism, mitochondria consist approximately of 500–1,400 different Proteins. By far most of these Proteins are encoded by nuclear genes and synthesized on cytosolic ribosomes. Targeting signals direct these Proteins into mitochondria and there to their respective subcompartment: the outer membrane, the intermembrane space (IMS), the inner membrane, and the matrix. Membrane-embedded translocation complexes allow the translocation of Proteins across and, in the case of membrane Proteins, the insertion into mitochondrial membranes. A small number of Proteins are encoded by the mitochondrial genome: Most mitochondrial translation products represent hydrophobic Proteins of the inner membrane which—together with many Nuclear-Encoded Proteins—form the respiratory chain complexes. This chapter gives an overview on the mitochondrial protein translocases and the mechanisms by which they drive the transport and assembly of mitochondrial Proteins.
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ribosome binding to the oxa1 complex facilitates co translational protein insertion in mitochondria
The EMBO Journal, 2003Co-Authors: Gregor Szyrach, Walter Neupert, Martin Ott, Nathalie Bonnefoy, Johannes M. HerrmannAbstract:The Oxa1 translocase of the mitochondrial inner membrane facilitates the insertion of both mitochondrially and nuclear‐encoded Proteins from the matrix into the inner membrane. Most mitochondrially encoded Proteins are hydrophobic membrane Proteins which are integrated into the lipid bilayer during their synthesis on mitochondrial ribosomes. The molecular mechanism of this co‐translational insertion process is unknown. Here we show that the matrix‐exposed C‐terminus of Oxa1 forms an α‐helical domain that has the ability to bind to mitochondrial ribosomes. Deletion of this Oxa1 domain strongly diminished the efficiency of membrane insertion of subunit 2 of cytochrome oxidase, a mitochondrially encoded substrate of the Oxa1 translocase. This suggests that co‐translational membrane insertion of mitochondrial translation products is facilitated by a physical interaction of translation complexes with the membrane‐bound translocase.
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Mba1, a novel component of the mitochondrial protein export machinery of the yeast Saccharomyces cerevisiae.
The Journal of cell biology, 2001Co-Authors: Marc Preuss, Walter Neupert, Rosemary A. Stuart, Klaus Leonhard, Kai Hell, Johannes M. HerrmannAbstract:The biogenesis of mitochondria requires the integration of many Proteins into the inner membrane from the matrix side. The inner membrane protein Oxa1 plays an important role in this process. We identified Mba1 as a second mitochondrial component that is required for efficient protein insertion. Like Oxa1, Mba1 specifically interacts both with mitochondrial translation products and with conservatively sorted, Nuclear-Encoded Proteins during their integration into the inner membrane. Oxa1 and Mba1 overlap in function and substrate specificity, but both can act independently of each other. We conclude that Mba1 is part of the mitochondrial protein export machinery and represents the first component of a novel Oxa1-independent insertion pathway into the mitochondrial inner membrane.
Uwe G. Maier - One of the best experts on this subject based on the ideXlab platform.
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An unusual ERAD-like complex is targeted to the apicoplast of Plasmodium falciparum.
Eukaryotic cell, 2009Co-Authors: Simone Spork, Uwe G. Maier, Maik S. Sommer, Jan A. Hiss, Katharina Mandel, Taco W. A. Kooij, Trang Chu, Gisbert Schneider, Jude M. PrzyborskiAbstract:Many apicomplexan parasites, including Plasmodium falciparum, harbor a so-called apicoplast, a complex plastid of red algal origin which was gained by a secondary endosymbiotic event. The exact molecular mechanisms directing the transport of Nuclear-Encoded Proteins to the apicoplast of P. falciparum are not well understood. Recently, in silico analyses revealed a second copy of Proteins homologous to components of the endoplasmic reticulum (ER)-associated protein degradation (ERAD) system in organisms with secondary plastids, including the malaria parasite P. falciparum. These Proteins are predicted to be endowed with an apicoplast targeting signal and are suggested to play a role in the transport of Nuclear-Encoded Proteins to the apicoplast. Here, we have studied components of this ERAD-derived putative preprotein translocon complex in malaria parasites. Using transfection technology coupled with fluorescence imaging techniques we can demonstrate that the N terminus of several ERAD-derived components targets green fluorescent protein to the apicoplast. Furthermore, we confirm that full-length PfsDer1-1 and PfsUba1 (homologues of yeast ERAD components) localize to the apicoplast, where PfsDer1-1 tightly associates with membranes. Conversely, PfhDer1-1 (a host-specific copy of the Der1-1 protein) localizes to the ER. Our data suggest that ERAD components have been “rewired” to provide a conduit for protein transport to the apicoplast. Our results are discussed in relation to the nature of the apicoplast protein transport machinery.
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complex chloroplast rna metabolism just debugging the genetic programme
BMC Biology, 2008Co-Authors: Uwe G. Maier, Andrew Bozarth, Helena T Funk, Stefan Zauner, Christian Schmitzlinneweber, Thomas Börner, Stefan A Rensing, Michael TillichAbstract:Background The gene expression system of chloroplasts is far more complex than that of their cyanobacterial progenitor. This gain in complexity affects in particular RNA metabolism, specifically the transcription and maturation of RNA. Mature chloroplast RNA is generated by a plethora of Nuclear-Encoded Proteins acquired or recruited during plant evolution, comprising additional RNA polymerases and sigma factors, and sequence-specific RNA maturation factors promoting RNA splicing, editing, end formation and translatability. Despite years of intensive research, we still lack a comprehensive explanation for this complexity.
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Transport of Nuclear-Encoded Proteins into secondarily evolved plastids.
Biological chemistry, 2007Co-Authors: Franziska Hempel, Andrew Bozarth, Stefan Zauner, Maik S. Sommer, Jude M. Przyborski, Uwe G. MaierAbstract:Many algal groups evolved by engulfment and intracellular reduction of a eukaryotic phototroph within a heterotrophic cell. Via this process, so-called secondary plastids evolved, surrounded by three or four membranes. In these organisms most of the genetic material encoding plastid functions is localized in the cell nucleus, with the result that many Proteins have to pass three, four, or even five membranes to reach their final destination within the plastid. In this article, we review recent models and findings that help to explain important cellular mechanisms involved in the complex process of protein transport into secondary plastids.
Vamsi K Mootha - One of the best experts on this subject based on the ideXlab platform.
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functional genomic analysis of human mitochondrial rna processing
Cell Reports, 2014Co-Authors: Ashley R Wolf, Vamsi K MoothaAbstract:Summary Both strands of human mtDNA are transcribed in continuous, multigenic units that are cleaved into the mature rRNAs, tRNAs, and mRNAs required for respiratory chain biogenesis. We sought to systematically identify Nuclear-Encoded Proteins that contribute to processing of mtRNAs within the organelle. First, we devised and validated a multiplex MitoString assay that quantitates 27 mature and precursor mtDNA transcripts. Second, we applied MitoString profiling to evaluate the impact of silencing each of 107 mitochondrial-localized, predicted RNA-binding Proteins. With the resulting data set, we rediscovered the roles of recently identified RNA-processing enzymes, detected unanticipated roles of known disease genes in RNA processing, and identified new regulatory factors. We demonstrate that one such factor, FASTKD4, modulates the half-lives of a subset of mt-mRNAs and associates with mtRNAs in vivo. MitoString profiling may be useful for diagnosing and deciphering the pathogenesis of mtDNA disorders.
