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PHB1 and PHB2 deletion cell proteome

ABSTRACT: Folding of newly synthesized proteins poses challenges for a functional proteome. Dedicated protein quality control (PQC) systems promote either the folding of nascent polypeptides at ribosomes or, if this fails, ensure their degradation. While well studied for cytosolic protein biogenesis, it is not understood how these processes work for mitochondrially-encoded proteins, key subunits of the oxidative phosphorylation system (OXPHOS). Here, we identify dedicated hubs in proximity to mitoribosomal tunnel exits coordinating mitochondrial translation, protein import, assembly, and protein turnover. Conserved prohibitin/m-AAA protease supercomplexes and the availability of assembly chaperones determine the fate of newly synthesized proteins by molecular triaging. The localization of these competing activities in vicinity to the mitoribosomal tunnel exit allows for a prompt decision whether newly synthesized proteins are fed into OXPHOS assembly or degraded. This repository hosts the whole proteome of PHB1/2 deletion cells and is related to other repositories:

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Saccharomyces Cerevisiae (baker's Yeast)

TISSUE(S): Cell Suspension Culture

SUBMITTER: Hendrik Nolte

LAB HEAD: Thomas Langer

PROVIDER: PXD043668 | Pride | 2023-08-14

REPOSITORIES: Pride

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			Action	DRS
	20221123_MaOt_0215_HSlJiYwdoGN9_001_WT_sample_01.raw	Raw
	20221123_MaOt_0215_HSlJiYwdoGN9_002_WT_sample_02.raw	Raw
	20221123_MaOt_0215_HSlJiYwdoGN9_003_WT_sample_03.raw	Raw
	20221123_MaOt_0215_HSlJiYwdoGN9_004_WT_sample_04.raw	Raw
	20221123_MaOt_0215_HSlJiYwdoGN9_005_WT_sample_05.raw	Raw

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Project description:Folding of newly synthesized proteins to the native state is a major challenge within the crowded cellular environment, since non-productive interactions can lead to misfolding, aggregation and degradation1. Cells cope with this challenge by coupling synthesis with polypeptide folding and by employing molecular chaperones to safeguard folding already cotranslationally2. However, little is known about the final step of folding, the assembly of polypeptides into complexes, although most of the cellular proteome forms oligomeric assemblies3. In prokaryotes, a proof-of-concept study showed that assembly of heterodimeric luciferase is an organized cotranslational process, facilitated by spatially confined translation of the subunits encoded on a polycistronic mRNA4. In eukaryotes, however, fundamental differences such as rarity of polycistronic mRNAs and different chaperone constellations raise the question whether assembly is also coordinated with translation. Here we provide a systematic and mechanistic analysis of protein complex assembly in eukaryotes using ribosome profiling. We determined the in vivo nascent subunits interactions of 12 hetero-oligomeric protein complexes of Saccharomyces cerevisiae at near-residue resolution. We find 9 complexes assemble cotranslationally; the 3 complexes that do not show cotranslational interactions are regulated by dedicated assembly chaperones5-7. Cotranslational assembly often occurs uni-directionally, with one fully synthesized subunit engaging its nascent partner subunit(s), thereby counteracting its aggregation propensity. The onset of cotranslational subunit association coincides sharply with full exposure of the nascent interaction domain at the ribosomal tunnel exit. The action of the ribosome-associated Hsp70 chaperone Ssb8 is coordinated with assembly. Ssb transiently engages partially synthesized interaction domains, then dissociates before the onset of partner subunit association, presumably to prevent premature assembly interactions. Our study shows that cotranslational subunit association is a prevalent mechanism for hetero-oligomers assembly in yeast and indicates that translation, folding and assembly of protein complexes are integrated processes in eukaryotes.

Project description:Background: Transcription control of mitochondrial metabolism is essential for cellular function. A better understanding of this process will aid the elucidation of mitochondrial disorders, in particular of the many genetically unsolved cases of oxidative phosphorylation (OXPHOS) deficiency. Yet, to date only few studies have investigated nuclear gene regulation in the context of OXPHOS deficiency. In this study, we combined RNA sequencing of human complex I-deficient patient cells across 32 conditions of perturbed mitochondrial metabolism, with a comprehensive analysis of gene expression patterns, co-expression calculations and transcription factor binding sites. Results: Our analysis shows that OXPHOS genes have a significantly higher co-expression with each other than with other genes, including mitochondrial genes. We found no evidence for complex-specific mRNA expression regulation in the tested cell types and conditions: subunits of different OXPHOS complexes are similarly (co-)expressed and regulated by a common set of transcription factors. However, we did observe significant differences between the expression of OXPHOS complex subunits compared to assembly factors, suggesting divergent transcription programs. Furthermore, complex I co-expression calculations identified 684 genes with a likely role in OXPHOS biogenesis and function. Analysis of evolutionarily conserved transcription factor binding sites in the promoters of these genes revealed almost all known OXPHOS regulators (including GABP, NRF1/2, SP1, YY1, E-box factors) and a set of six yet uncharacterized candidate transcription factors (ELK1, KLF7, SP4, EHF, ZNF143, and EL2). Conclusions: OXPHOS genes share an expression program distinct from other mitochondrial genes, indicative of targeted regulation of this mitochondrial sub-process. Within the subset of OXPHOS genes we established a difference in expression between subunits and assembly factors. Most transcription regulators of genes that co-express with complex I are well-established factors for OXPHOS biogenesis. For the remaining six factors we here suggest for the first time a link with transcription regulation in OXPHOS deficiency. RNA-SEQ of whole cell RNA in 2 control and 2 complex I deficient patient fibroblast cell lines treated with 4 compounds in duplicate, resulting in a total of 2x2x4x2=32 samples

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PHB1 and PHB2 deletion cell proteome

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