An update to the CRM1 cargo/NES database NESdb.
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ABSTRACT:
SUBMITTER: Fung HYJ
PROVIDER: S-EPMC8101443 | biostudies-literature | 2021 Mar
REPOSITORIES: biostudies-literature
Publications
An update to the CRM1 cargo/NES database NESdb.
Fung Ho Yee Joyce HYJ Niesman Ashley A Chook Yuh Min YM
Molecular biology of the cell 20210301 6
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Project description:MotivationThe consensus pattern of Nuclear Export Signal (NES) is a short sequence motif that is commonly identified in protein sequences, whether the motif acts as an NES (true positive) or not (false positive). Finding more plausible NES functioning regions among the vast array of consensus-matching segments would provide an interesting resource for further experimental validation. Better defined NES should also allow meaningful mapping of cancer-related mutation positions, leading to plausible explanations for the relationship between nuclear export and disease.ResultsPossible NES candidate regions are extracted from the cancer-related human reference proteome. Extracted NES are scored for reliability by combining sequence-based and structure-based approaches. The confidently identified NES candidate motifs were checked for overlap with cancer-related mutation positions annotated in the COSMIC database. Among the ∼700 cancer-related sequences in the COSMIC Cancer Gene Census, 178 sequences are predicted to have possible NES motifs containing cancer-related mutations at their key positions. These lists are organized into our database (pCRM1exportome), and other protein sequences in the human reference proteome can also be retrieved by their UniProt IDs.Availability and implementationThe database is freely available at http://prodata.swmed.edu/pCRM1exportome.Supplementary informationSupplementary data are available at Bioinformatics online.
| S-EPMC8496372 | biostudies-literature
Project description:CRM1 (Exportin1/XPO1) exports hundreds of broadly functioning protein cargoes out of the cell nucleus by binding to their classical nuclear export signals (NESs). The 8- to 15-amino-acid-long NESs contain four to five hydrophobic residues and are highly diverse in both sequence and CRM1-bound structure. Here we examine the relationship between nuclear export activities of 24 different NES peptides in cells and their CRM1-NES affinities. We found that binding affinity and nuclear export activity are linearly correlated for NESs with dissociation constants ( Kds) between tens of nanomolar to tens of micromolar. NESs with Kds outside this range have significantly reduced nuclear export activities. These include two unusually tight-binding peptides, one from the nonstructural protein 2 of murine minute virus (MVM NS2) and the other a mutant of the protein kinase A inhibitor (PKI) NES. The crystal structure of CRM1-bound MVM NS2NES suggests that extraordinarily tight CRM1 binding arises from intramolecular contacts within the NES that likely stabilizes the CRM1-bound conformation in free peptides. This mechanistic understanding led to the design of two novel peptide inhibitors that bind CRM1 with picomolar affinity.
| S-EPMC6232958 | biostudies-literature
Project description:The nuclear export receptor CRM1 (XPO1) recognizes and binds specific sequence motifs termed nuclear export signals (NESs) in cargo proteins. About 200 NES motifs have been identified, but over a thousand human proteins are potential CRM1 cargos, and most of their NESs remain to be identified. On the other hand, the interaction of NES peptides with the "NES-binding groove" of CRM1 was studied in detail using structural and biochemical analyses, but a better understanding of CRM1 function requires further investigation of how the results from these in vitro studies translate into actual NES export in a cellular context. Here we show that a simple cellular assay, based on a recently described reporter (SRVB/A), can be applied to identify novel potential NESs motifs, and to obtain relevant information on different aspects of CRM1-mediated NES export. Using cellular assays, we first map 19 new sequence motifs with nuclear export activity in 14 cancer-related proteins that are potential CRM1 cargos. Next, we investigate the effect of mutations in individual NES-binding groove residues, providing further insight into CRM1-mediated NES export. Finally, we extend the search for CRM1-dependent NESs to a recently uncovered, but potentially vast, set of small proteins called micropeptides. By doing so, we report the first NES-harboring human micropeptides.
| S-EPMC7503480 | biostudies-literature
Project description:CRM1 or XPO1 is the major nuclear export receptor in the cell, which controls the nuclear-cytoplasmic localization of many proteins and RNAs. CRM1 is also a promising cancer drug target as the transport receptor is overexpressed in many cancers where some of its cargos are misregulated and mislocalized to the cytoplasm. Atomic level understanding of CRM1 function has greatly facilitated recent drug discovery and development of CRM1 inhibitors to target a variety of malignancies. Numerous atomic resolution CRM1 structures are now available, explaining how the exporter recognizes nuclear export signals in its cargos, how RanGTP and cargo bind with positive cooperativity, how RanBP1 causes release of export cargos in the cytoplasm and how diverse inhibitors such as Leptomycin B and the new KPT-SINE compounds block nuclear export. This review summarizes structure-function studies that explain CRM1-cargo recognition, release and inhibition.
| S-EPMC4108548 | biostudies-literature
Project description:The transport receptor Crm1 mediates the export of diverse cargos containing leucine-rich nuclear export signals (NESs) through complex formation with RanGTP. To ensure efficient cargo release in the cytoplasm, NESs have evolved to display low affinity for Crm1. However, mechanisms that overcome low affinity to assemble Crm1-export complexes in the nucleus remain poorly understood. In this study, we reveal a new type of RanGTP-binding protein, Slx9, which facilitates Crm1 recruitment to the 40S pre-ribosome-associated NES-containing adaptor Rio2. In vitro, Slx9 binds Rio2 and RanGTP, forming a complex. This complex directly loads Crm1, unveiling a non-canonical stepwise mechanism to assemble a Crm1-export complex. A mutation in Slx9 that impairs Crm1-export complex assembly inhibits 40S pre-ribosome export. Thus, Slx9 functions as a scaffold to optimally present RanGTP and the NES to Crm1, therefore, triggering 40S pre-ribosome export. This mechanism could represent one solution to the paradox of weak binding events underlying rapid Crm1-mediated export.
| S-EPMC4402694 | biostudies-literature
Project description:Many cellular responses rely on the control of nucleocytoplasmic transport of transcriptional regulators. The Drosophila nucleoporin Nup88 is selectively required for nuclear accumulation of Rel proteins and full activation of the innate immune response. Here, we investigate the mechanisms underlying its role in nucleocytoplasmic transport. Nuclear import of an nuclear localization signal-enhanced green fluorescent protein (NLS-EGFP) reporter is not affected in DNup88 (members only; mbo) mutants, whereas the level of CRM1-dependent EGFP-nuclear export signal (EGFP-NES) export is increased. We show that the nuclear accumulation of the Drosophila Rel protein Dorsal requires CRM1. DNup88 binds to DNup214 and DCRM1 in vitro, and both proteins become mislocalized from the nuclear rim into the nucleus of mbo mutants. Overexpression of DNup88 is sufficient to relocalize DNup214 and CRM1 on the nuclear envelope and revert the mutant phenotypes. We propose that a major function of DNup88 is to anchor DNup214 and CRM1 on the nuclear envelope and thereby attenuate NES-mediated nuclear export.
| S-EPMC2173670 | biostudies-literature
Project description:MotivationClassical nuclear export signals (NESs) are short cognate peptides that direct proteins out of the nucleus via the CRM1-mediated export pathway. CRM1 regulates the localization of hundreds of macromolecules involved in various cellular functions and diseases. Due to the diverse and complex nature of NESs, reliable prediction of the signal remains a challenge despite several attempts made in the last decade.ResultsWe present a new NES predictor, LocNES. LocNES scans query proteins for NES consensus-fitting peptides and assigns these peptides probability scores using Support Vector Machine model, whose feature set includes amino acid sequence, disorder propensity, and the rank of position-specific scoring matrix score. LocNES demonstrates both higher sensitivity and precision over existing NES prediction tools upon comparative analysis using experimentally identified NESs.Availability and implementationLocNES is freely available at http://prodata.swmed.edu/LocNES CONTACT: yuhmin.chook@utsouthwestern.eduSupplementary informationSupplementary data are available at Bioinformatics online.
| S-EPMC4410651 | biostudies-literature
Project description:The karyopherin CRM1 mediates nuclear export of proteins and ribonucleoproteins bearing a leucine-rich nuclear export signal (NES). To elucidate the precise mechanism by which NES-cargos are dissociated from CRM1 in the cytoplasm, which is important for transport directionality, we determined a 2.0-A resolution crystal structure of yeast CRM1:RanBP1:RanGTP complex, an intermediate in the disassembly of the CRM1 nuclear export complex. The structure shows that on association of Ran-binding domain (RanBD) of RanBP1 with CRM1:NES-cargo:RanGTP complex, RanBD and the C-terminal acidic tail of Ran induce a large movement of the intra-HEAT9 loop of CRM1. The loop moves to the CRM1 inner surface immediately behind the NES-binding site and causes conformational rearrangements in HEAT repeats 11 and 12 so that the hydrophobic NES-binding cleft on the CRM1 outer surface closes, squeezing out the NES-cargo. This allosteric mechanism accelerates dissociation of NES by over two orders of magnitude. Structure-based mutagenesis indicated that the HEAT9 loop also functions as an allosteric autoinhibitor to stabilize CRM1 in a conformation that is unable to bind NES-cargo in the absence of RanGTP.
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Project description:The Clusters of Orthologous Genes (COG) database, originally created in 1997, has been updated to reflect the constantly growing collection of completely sequenced prokaryotic genomes. This update increased the genome coverage from 1309 to 2296 species, including 2103 bacteria and 193 archaea, in most cases, with a single representative genome per genus. This set covers all genera of bacteria and archaea that included organisms with 'complete genomes' as per NCBI databases in November 2023. The number of COGs has been expanded from 4877 to 4981, primarily by including protein families involved in bacterial protein secretion. Accordingly, COG pathways and functional groups now include secretion systems of types II through X, as well as Flp/Tad and type IV pili. These groupings allow straightforward identification and examination of the prokaryotic lineages that encompass-or lack-a particular secretion system. Other developments include improved annotations for the rRNA and tRNA modification proteins, multi-domain signal transduction proteins, and some previously uncharacterized protein families. The new version of COGs is available at https://www.ncbi.nlm.nih.gov/research/COG, as well as on the NCBI FTP site https://ftp.ncbi.nlm.nih.gov/pub/COG/, which also provides archived data from previous COG releases.
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