Project description:During the co-translational assembly of protein complexes, a fully synthesized subunit engages with the nascent chain of a newly synthesized interaction partner. Such events are thought to contribute to productive assembly, but their exact physiological relevance remains underexplored. Here, we examined structural motifs contained in nucleoporins for their potential to facilitate co-translational assembly. We experimentally tested candidate structural motifs and identified several previously unknown co-translational interactions. We demonstrate by selective ribosome profiling that domain invasion motifs of beta-propellers, coiled-coils, and short linear motifs act as co-translational assembly domains. Such motifs are often contained in proteins that are members of multiple complexes (moonlighters) and engage with closely related paralogs. Surprisingly, moonlighters and paralogs assembled co-translationally in only one but not all of the relevant assembly pathways. Our results highlight the regulatory complexity of assembly pathways. During the co-translational assembly of protein complexes, a fully synthesized subunit engages with the nascent chain of a newly synthesized interaction partner. Such events are thought to contribute to productive assembly, but their exact physiological relevance remains underexplored. Here, we examined structural motifs contained in nucleoporins for their potential to facilitate co-translational assembly. We experimentally tested candidate structural motifs and identified several previously unknown co-translational interactions. We demonstrate by selective ribosome profiling that domain invasion motifs of beta-propellers, coiled-coils, and short linear motifs act as co-translational assembly domains. Such motifs are often contained in proteins that are members of multiple complexes (moonlighters) and engage with closely related paralogs. Surprisingly, moonlighters and paralogs assembled co-translationally in only one but not all of the relevant assembly pathways. Our results highlight the regulatory complexity of assembly pathways.
Project description:During the co-translational assembly of protein complexes, a fully synthesized subunit engages with the nascent chain of a newly synthesized interaction partner. Such events are thought to contribute to productive assembly, but their exact physiological relevance remains underexplored. Here, we examined structural motifs contained in nucleoporins for their potential to facilitate co-translational assembly. We experimentally tested candidate structural motifs and identified several previously unknown co-translational interactions. We demonstrate by selective ribosome profiling that domain invasion motifs of beta-propellers, coiled-coils, and short linear motifs act as co-translational assembly domains. Such motifs are often contained in proteins that are members of multiple complexes (moonlighters) and engage with closely related paralogs. Surprisingly, moonlighters and paralogs assembled co-translationally in only one but not all of the relevant assembly pathways. Our results highlight the regulatory complexity of assembly pathways. During the co-translational assembly of protein complexes, a fully synthesized subunit engages with the nascent chain of a newly synthesized interaction partner. Such events are thought to contribute to productive assembly, but their exact physiological relevance remains underexplored. Here, we examined structural motifs contained in nucleoporins for their potential to facilitate co-translational assembly. We experimentally tested candidate structural motifs and identified several previously unknown co-translational interactions. We demonstrate by selective ribosome profiling that domain invasion motifs of beta-propellers, coiled-coils, and short linear motifs act as co-translational assembly domains. Such motifs are often contained in proteins that are members of multiple complexes (moonlighters) and engage with closely related paralogs. Surprisingly, moonlighters and paralogs assembled co-translationally in only one but not all of the relevant assembly pathways. Our results highlight the regulatory complexity of assembly pathways.
2022-02-11 | PXD028413 | Pride
Project description:Co-translational protein folding by AP Profiling
Project description:Many environmental, genetic, and epigenetic factors are known to affect the frequency and positioning of meiotic crossovers (COs). Suppression of COs by large, cytologically visible inversions and translocations has long been recognized, but relatively little is known about how smaller structural variants (SVs) affect COs. To examine fine-scale determinants of the CO landscape, including SVs, we used a rapid, cost-effective method for high-throughput sequencing to generate a precise map of over 17,000 COs between the Col-0 and Ler accessions of Arabidopsis thaliana. COs were generally suppressed in regions with SVs, but this effect did not depend on the size of the variant region, and was only marginally affected by the variant type. CO suppression did not extend far beyond the SV borders, and CO rates were slightly elevated in the flanking regions. Disease resistance gene clusters, which often exist as SVs, exhibited high CO rates at some loci, but there was a tendency toward depressed CO rates at loci where large structural differences exist between the two parents. Our high-density map also revealed in fine detail how CO positioning relates to genetic (DNA motifs) and epigenetic (chromatin structure) features of the genome. We conclude that suppression of COs occurs over a narrow region spanning large and small-scale SVs, representing influence on the CO landscape in addition to sequence and epigenetic variation along chromosomes.
Project description:RNA immunoprecipitation using mouse monoclonal antibody against human TAF10 protein from HeLa polysome extracts Cells dedicate significant energy to building proteins1, which are often organized in multiprotein assemblies with tightly regulated stoichiometries2. Cotranslational assembly, a process of synchronous translation and protein heterodimerization, is a potential mechanism for efficient matching of partner subunits and avoiding the negative effects of protein aggregation3. Recent studies in bacteria demonstrate that cotranslational assembly of the LuxA-LuxB dimer follows the order established by operon structure and is more efficient than post-translational assembly4. As genes encoding protein complex subunits are dispersed among chromosomes in eukaryotes, it is unclear how cotranslational assembly is accomplished mechanistically, but studies in yeast have nevertheless suggested it as a potential assembly pathway5,6,7. Here we show that mammalian transcription complexes, such as the RNA polymerase II general transcription factor TFIID and the TRanscription and EXport complex-2 (TREX-2) assemble co-translationally. Moreover, we show that the position of heterodimerization domains determines the order of cotranslational assembly in mammalian TFIID. In polysomes, the TATA binding protein associated factor 10 (TAF10), which contains a C-terminal histone-fold dimerization domain (HFD) is recruited cotranslationally to its HFD-containing binding partner TAF8. This interaction is established unidirectionally and determined by the position rather than the sequence of the dimerization domain. We further show that similar mechanisms guide the assembly of other TFIID subunits. Our results thus predict that cotranslational assembly of eukaryotic multisubunit complexes is a general principle in building multiprotein machines. We used microarrays to assess globally the mRNAs associated with TAF10 and TBP immunoprecipitations from HeLa polysomes.
Project description:Large heteromeric multiprotein complexes play pivotal roles at every step of gene expression in eukaryotic cells. Among them, the 20-subunits basal transcription factor TFIID nucleates RNA polymerase II preinitiation complex at gene promoters. Here, by combining systematic RNA-immunoprecipitation experiments, single-molecule imaging, proteomics and structure-function analyses, we show that TFIID is built using co-translational assembly. We discovered that all early steps of TFIID assembly, involving protein heterodimerization, happen during protein synthesis. Strikingly, we identify TAF1 – the largest protein in the complex – as a flexible scaffold subunit that co-translationally recruits preassembled TFIID submodules found populating the cytoplasm of cells. Consequently, TAF1 depletion leads to a cytoplasmic accumulation of TFIID building blocks. Altogether, our data suggest a multistep hierarchical model for TFIID biogenesis that culminates with the co-translational assembly on nascent TAF1 polypeptide, that works as a ‘driver’ subunit. We envision that this assembly strategy could be shared with other large heteromeric protein complexes.
2023-07-04 | PXD036358 | Pride
Project description:CBP80 orchestrates co-translational protein targeting to endoplasmic reticulum.
Project description:To obtain a molecular-level understanding of biological processes, it is critical to perform structural characterization of protein complexes and their subunits directly from human tissues. Native top-down mass spectrometry (MS) has emerged as a complementary technique to traditional structural biology methods. Nonetheless, native top-down MS has primarily characterized recombinant or high-abundance protein complexes, as strategies to enrich and preserve low-abundance protein complexes from human tissues is lacking. Here we have developed a native nanoproteomics platform integrating peptide-functionalized nanoparticles to characterize low-abundance protein complexes with high-resolution native top-down MS. We then apply our native nanoproteomics strategy to enrich and structurally elucidate endogenous troponin (cTn) complexes directly from human heart tissue. Our results not only reveal the native complex assembly, post-translational modification landscape, and Ca2+ binding dynamics of the cTn complex but also enable us to propose a paradigm for structural and dynamical characterization of endogenous native protein complexes from human tissues.
Project description:While the protein composition of various yeast 60S ribosomal subunit assembly intermediates has been studied in detail, little is known about ribosomal RNA (rRNA) structural rearrangements that take place during early 60S assembly steps. Using a high-throughput RNA structure probing method, we provide nucleotide resolution insights into rRNA structural rearrangements during nucleolar 60S assembly. Our results suggest that many rRNA-folding steps, such as folding of 5.8S rRNA, occur at a very specific stage of assembly, and propose that downstream nuclear assembly events can only continue once 5.8S folding has been completed. Our maps of nucleotide flexibility enable making predictions about the establishment of protein-rRNA interactions, providing intriguing insights into the temporal order of protein-rRNA as well as long-range inter-domain rRNA interactions. These data argue that many distant domains in the rRNA can assemble simultaneously during early 60S assembly and underscore the enormous complexity of 60S synthesis.Ribosome biogenesis is a dynamic process that involves the ordered assembly of ribosomal proteins and numerous RNA structural rearrangements. Here the authors apply ChemModSeq, a high-throughput RNA structure probing method, to quantitatively measure changes in RNA flexibility during the nucleolar stages of 60S assembly in yeast.