Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Conservation of complex knotting and slipknotting patterns in proteins.

ABSTRACT: While analyzing all available protein structures for the presence of knots and slipknots, we detected a strict conservation of complex knotting patterns within and between several protein families despite their large sequence divergence. Because protein folding pathways leading to knotted native protein structures are slower and less efficient than those leading to unknotted proteins with similar size and sequence, the strict conservation of the knotting patterns indicates an important physiological role of knots and slipknots in these proteins. Although little is known about the functional role of knots, recent studies have demonstrated a protein-stabilizing ability of knots and slipknots. Some of the conserved knotting patterns occur in proteins forming transmembrane channels where the slipknot loop seems to strap together the transmembrane helices forming the channel.

SUBMITTER: Sulkowska JI

PROVIDER: S-EPMC3387036 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Conservation of complex knotting and slipknotting patterns in proteins.

Sułkowska Joanna I JI Rawdon Eric J EJ Millett Kenneth C KC Onuchic Jose N JN Stasiak Andrzej A

Proceedings of the National Academy of Sciences of the United States of America 20120608 26

While analyzing all available protein structures for the presence of knots and slipknots, we detected a strict conservation of complex knotting patterns within and between several protein families despite their large sequence divergence. Because protein folding pathways leading to knotted native protein structures are slower and less efficient than those leading to unknotted proteins with similar size and sequence, the strict conservation of the knotting patterns indicates an important physiolog ...[more]

PMID: 22685208

Similar Datasets

Subfamily specific conservation profiles for proteins based on n-gram patterns.

Project description:BACKGROUND:A new algorithm has been developed for generating conservation profiles that reflect the evolutionary history of the subfamily associated with a query sequence. It is based on n-gram patterns (NP{n,m}) which are sets of n residues and m wildcards in windows of size n+m. The generation of conservation profiles is treated as a signal-to-noise problem where the signal is the count of n-gram patterns in target sequences that are similar to the query sequence and the noise is the count over all target sequences. The signal is differentiated from the noise by applying singular value decomposition to sets of target sequences rank ordered by similarity with respect to the query. RESULTS:The new algorithm was used to construct 4,248 profiles from 120 randomly selected Pfam-A families. These were compared to profiles generated from multiple alignments using the consensus approach. The two profiles were similar whenever the subfamily associated with the query sequence was well represented in the multiple alignment. It was possible to construct subfamily specific conservation profiles using the new algorithm for subfamilies with as few as five members. The speed of the new algorithm was comparable to the multiple alignment approach. CONCLUSION:Subfamily specific conservation profiles can be generated by the new algorithm without aprioi knowledge of family relationships or domain architecture. This is useful when the subfamily contains multiple domains with different levels of representation in protein databases. It may also be applicable when the subfamily sample size is too small for the multiple alignment approach.

| S-EPMC2267698 | biostudies-literature

Conservation and variability of synaptonemal complex proteins in phylogenesis of eukaryotes.

Project description:The problems of the origin and evolution of meiosis include the enigmatic variability of the synaptonemal complexes (SCs) which, being morphology similar, consist of different proteins in different eukaryotic phyla. Using bioinformatics methods, we monitored all available eukaryotic proteomes to find proteins similar to known SC proteins of model organisms. We found proteins similar to SC lateral element (LE) proteins and possessing the HORMA domain in the majority of the eukaryotic taxa and assume them the most ancient among all SC proteins. Vertebrate LE proteins SYCP2, SYCP3, and SC65 proved to have related proteins in many invertebrate taxa. Proteins of SC central space are most evolutionarily variable. It means that different protein-protein interactions can exist to connect LEs. Proteins similar to the known SC proteins were not found in Euglenophyta, Chrysophyta, Charophyta, Xanthophyta, Dinoflagellata, and primitive Coelomata. We conclude that different proteins whose common feature is the presence of domains with a certain conformation are involved in the formation of the SC in different eukaryotic phyla. This permits a targeted search for orthologs of the SC proteins using phylogenetic trees. Here we consider example of phylogenetic trees for protozoans, fungi, algae, mosses, and flowering plants.

| S-EPMC4132317 | biostudies-literature

Knotting and unknotting proteins in the chaperonin cage: Effects of the excluded volume.

Project description:Molecular dynamics simulations are used to explore the effects of chaperonin-like cages on knotted proteins with very low sequence similarity, different depths of a knot but with a similar fold, and the same type of topology. The investigated proteins are VirC2, DndE and MJ0366 with two depths of a knot. A comprehensive picture how encapsulation influences folding rates is provided based on the analysis of different cage sizes and temperature conditions. Neither of these two effects with regard to knotted proteins has been studied by means of molecular dynamics simulations with coarse-grained structure-based models before. We show that encapsulation in a chaperonin is sufficient to self-tie and untie small knotted proteins (VirC2, DndE), for which the equilibrium process is not accessible in the bulk solvent. Furthermore, we find that encapsulation reduces backtracking that arises from the destabilisation of nucleation sites, smoothing the free energy landscape. However, this effect can also be coupled with temperature rise. Encapsulation facilitates knotting at the early stage of folding and can enhance an alternative folding route. Comparison to unknotted proteins with the same fold shows directly how encapsulation influences the free energy landscape. In addition, we find that as the size of the cage decreases, folding times increase almost exponentially in a certain range of cage sizes, in accordance with confinement theory and experimental data for unknotted proteins.

| S-EPMC5425179 | biostudies-literature

Hydra meiosis reveals unexpected conservation of structural synaptonemal complex proteins across metazoans.

Project description:The synaptonemal complex (SC) is a key structure of meiosis, mediating the stable pairing (synapsis) of homologous chromosomes during prophase I. Its remarkable tripartite structure is evolutionarily well conserved and can be found in almost all sexually reproducing organisms. However, comparison of the different SC protein components in the common meiosis model organisms Saccharomyces cerevisiae, Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, and Mus musculus revealed no sequence homology. This discrepancy challenged the hypothesis that the SC arose only once in evolution. To pursue this matter we focused on the evolution of SYCP1 and SYCP3, the two major structural SC proteins of mammals. Remarkably, our comparative bioinformatic and expression studies revealed that SYCP1 and SYCP3 are also components of the SC in the basal metazoan Hydra. In contrast to previous assumptions, we therefore conclude that SYCP1 and SYCP3 form monophyletic groups of orthologous proteins across metazoans.

| S-EPMC3478637 | biostudies-literature

Patterns of sequence conservation in the S-Layer proteins and related sequences in Clostridium difficile.

Project description:Clostridium difficile is the etiological agent of antibiotic-associated diarrhea. Among the factors that may play a role in infection are S-layer proteins (SLPs). Previous work has shown these to consist mainly of two components, resulting from the cleavage of a precursor encoded by the slpA gene. The high-molecular-weight (MW) subunit is related both to amidases from B. subtilis and to at least another 28 gene products in C. difficile strain 630. To gain insight into the functions of the SLPs and related proteins, we have further investigated the pattern of variability both at the slpA locus and at six nearby paralogs. Sequencing of the slpA gene from an S-layer group II strain and a variant S-layer group strain confirms a high degree of divergence in the low-MW SLP, which may result from diversifying selection. A highly conserved motif, however, is found at the C terminus in all low-MW subunits and may be essential for SlpA precursor cleavage. In strain 167, a variant cleavage product is present, suggesting a secondary processing site. Southern blotting analysis shows slpA-like open reading frames (ORFs) 2 to 7 to be conserved in all nine strains tested, with one exception: ORF2, which encodes a 66-kDa polypeptide coextracted at low pH with the main SLPs in strain 630, may be partially deleted in strain 167. Polymorphism within the slpA-ORF7 cluster may be more pronounced in the region proximal to the slpA gene. Unexpectedly, a high-MW subunit probe cross hybridizes to sequences outside the slpA locus, which appear to vary in number in different strains.

| S-EPMC135169 | biostudies-literature

Conservation of regulatory sequences and gene expression patterns in the disintegrating Drosophila Hox gene complex.

Project description:Homeotic (Hox) genes are usually clustered and arranged in the same order as they are expressed along the anteroposterior body axis of metazoans. The mechanistic explanation for this colinearity has been elusive, and it may well be that a single and universal cause does not exist. The Hox-gene complex (HOM-C) has been rearranged differently in several Drosophila species, producing a striking diversity of Hox gene organizations. We investigated the genomic and functional consequences of the two HOM-C splits present in Drosophila buzzatii. Firstly, we sequenced two regions of the D. buzzatii genome, one containing the genes labial and abdominal A, and another one including proboscipedia, and compared their organization with that of D. melanogaster and D. pseudoobscura in order to map precisely the two splits. Then, a plethora of conserved noncoding sequences, which are putative enhancers, were identified around the three Hox genes closer to the splits. The position and order of these enhancers are conserved, with minor exceptions, between the three Drosophila species. Finally, we analyzed the expression patterns of the same three genes in embryos and imaginal discs of four Drosophila species with different Hox-gene organizations. The results show that their expression patterns are conserved despite the HOM-C splits. We conclude that, in Drosophila, Hox-gene clustering is not an absolute requirement for proper function. Rather, the organization of Hox genes is modular, and their clustering seems the result of phylogenetic inertia more than functional necessity.

| S-EPMC1088297 | biostudies-literature

Does conservation account for splicing patterns?

Project description:Alternative mRNA splicing is critical to proteomic diversity and tissue and species differentiation. Exclusion of cassette exons, also called exon skipping, is the most common type of alternative splicing in mammals.We present a computational model that predicts absolute (though not tissue-differential) percent-spliced-in of cassette exons more accurately than previous models, despite not using any 'hand-crafted' biological features such as motif counts. We achieve nearly identical performance using only the conservation score (mammalian phastCons) of each splice junction normalized by average conservation over 100 bp of the corresponding flanking intron, demonstrating that conservation is an unexpectedly powerful indicator of alternative splicing patterns. Using this method, we provide evidence that intronic splicing regulation occurs predominantly within 100 bp of the alternative splice sites and that conserved elements in this region are, as expected, functioning as splicing regulators. We show that among conserved cassette exons, increased conservation of flanking introns is associated with reduced inclusion. We also propose a new definition of intronic splicing regulatory elements (ISREs) that is independent of conservation, and show that most ISREs do not match known binding sites or splicing factors despite being predictive of percent-spliced-in.These findings suggest that one mechanism for the evolutionary transition from constitutive to alternative splicing is the emergence of cis-acting splicing inhibitors. The association of our ISREs with differences in splicing suggests the existence of novel RNA-binding proteins and/or novel splicing roles for known RNA-binding proteins.

| S-EPMC5055659 | biostudies-other

ConSurf-DB: An accessible repository for the evolutionary conservation patterns of the majority of PDB proteins.

Project description:Patterns observed by examining the evolutionary relationships among proteins of common origin can reveal the structural and functional importance of specific residue positions. In particular, amino acids that are highly conserved (i.e., their positions evolve at a slower rate than other positions) are particularly likely to be of biological importance, for example, for ligand binding. ConSurf is a bioinformatics tool for accurately estimating the evolutionary rate of each position in a protein family. Here we introduce a new release of ConSurf-DB, a database of precalculated ConSurf evolutionary conservation profiles for proteins of known structure. ConSurf-DB provides high-accuracy estimates of the evolutionary rates of the amino acids in each protein. A reliable estimate of a query protein's evolutionary rates depends on having a sufficiently large number of effective homologues (i.e., nonredundant yet sufficiently similar). With current sequence data, ConSurf-DB covers 82% of the PDB proteins. It will be updated on a regular basis to ensure that coverage remains high-and that it might even increase. Much effort was dedicated to improving the user experience. The repository is available at https://consurfdb.tau.ac.il/. BROADER AUDIENCE: By comparing a protein to other proteins of similar origin, it is possible to determine the extent to which each amino acid position in the protein evolved slowly or rapidly. A protein's evolutionary profile can provide valuable insights: For example, amino acid positions that are highly conserved (i.e., evolved slowly) are particularly likely to be of structural and/or functional importance, for example, for ligand binding and catalysis. We introduce here a new and improved version of ConSurf-DB, a continually updated database that provides precalculated evolutionary profiles of proteins with known structure.

| S-EPMC6933843 | biostudies-literature

Ser/Thr motifs in transmembrane proteins: conservation patterns and effects on local protein structure and dynamics.

Project description:We combined systematic bioinformatics analyses and molecular dynamics simulations to assess the conservation patterns of Ser and Thr motifs in membrane proteins, and the effect of such motifs on the structure and dynamics of α-helical transmembrane (TM) segments. We find that Ser/Thr motifs are often present in β-barrel TM proteins. At least one Ser/Thr motif is present in almost half of the sequences of α-helical proteins analyzed here. The extensive bioinformatics analyses and inspection of protein structures led to the identification of molecular transporters with noticeable numbers of Ser/Thr motifs within the TM region. Given the energetic penalty for burying multiple Ser/Thr groups in the membrane hydrophobic core, the observation of transporters with multiple membrane-embedded Ser/Thr is intriguing and raises the question of how the presence of multiple Ser/Thr affects protein local structure and dynamics. Molecular dynamics simulations of four different Ser-containing model TM peptides indicate that backbone hydrogen bonding of membrane-buried Ser/Thr hydroxyl groups can significantly change the local structure and dynamics of the helix. Ser groups located close to the membrane interface can hydrogen bond to solvent water instead of protein backbone, leading to an enhanced local solvation of the peptide.

| S-EPMC3910433 | biostudies-literature

Exploring knotting mechanisms in protein folding.

Project description:One of the most striking topological features to be found in a protein is that of a distinct knot formed by the path of the polypeptide backbone. Such knotted structures represent some of the smallest "self-tying" knots observed in Nature. Proteins containing a knot deep within their structure add an extra complication to the already challenging protein-folding problem; it is not obvious how, during the process of folding, a substantial length of polypeptide chain manages to spontaneously thread itself through a loop. Here, we probe the folding mechanism of YibK, a homodimeric alpha/beta-knot protein containing a deep trefoil knot at its carboxy terminus. By analyzing the effect of mutations made in the knotted region of the protein we show that the native structure in this area remains undeveloped until very late in the folding reaction. Single-site destabilizing mutations made in the knot structure significantly affect only the folding kinetics of a late-forming intermediate and the slow dimerization step. Furthermore, we find evidence to suggest that the heterogeneity observed in the denatured state is not caused by isomerization of the single cis proline bond as previously thought, but instead could be a result of the knotting mechanism. These results allow us to propose a folding model for YibK where the threading of the polypeptide chain and the formation of native structure in the knotted region of the protein occur independently as successive events.

| S-EPMC2596204 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data