Dataset Information

PcrG protects the two long helical oligomerization domains of PcrV, by an interaction mediated by the intramolecular coiled-coil region of PcrG.

ABSTRACT: BACKGROUND: PcrV is a hydrophilic translocator of type three secretion system (TTSS) and a structural component of the functional translocon. C-terminal helix of PcrV is essential for its oligomerization at the needle tip. Conformational changes within PcrV regulate the effector translocation. PcrG is a cytoplasmic regulator of TTSS and forms a high affinity complex with PcrV. C-terminal residues of PcrG control the effector secretion. RESULT: Both PcrV and PcrG-PcrV complex exhibit elongated conformation like their close homologs LcrV and LcrG-LcrV complex. The homology model of PcrV depicts a dumbbell shaped structure with N and C-terminal globular domains. The grip of the dumbbell is formed by two long helices (helix-7 and 12), which show high level of conservation both structurally and evolutionary. PcrG specifically protects a region of PcrV extending from helix-12 to helix-7, and encompassing the C-terminal globular domain. This fragment ?PcrV(128-294) interacts with PcrG with high affinity, comparable to the wild type interaction. Deletion of N-terminal globular domain leads to the oligomerization of PcrV, but PcrG restores the monomeric state of PcrV by forming a heterodimeric complex. The N-terminal globular domain (?PcrV(1-127)) does not interact with PcrG but maintains its monomeric state. Interaction affinities of various domains of PcrV with PcrG illustrates that helix-12 is the key mediator of PcrG-PcrV interaction, supported by helix-7. Bioinformatic analysis and study with our deletion mutant ?PcrG(13-72) revealed that the first predicted intramolecular coiled-coil domain of PcrG contains the PcrV interaction site. However, 12?N-terminal amino acids of PcrG play an indirect role in PcrG-PcrV interaction, as their deletion causes 40-fold reduction in binding affinity and changes the kinetic parameters of interaction. ?PcrG(13-72) fits within the groove formed between the two globular domains of PcrV, through hydrophobic interaction. CONCLUSION: PcrG interacts with PcrV through its intramolecular coiled-coil region and masks the domains responsible for oligomerization of PcrV at the needle tip. Also, PcrG could restore the monomeric state of oligomeric PcrV. Therefore, PcrG prevents the premature oligomerization of PcrV and maintains its functional state within the bacterial cytoplasm, which is a pre-requisite for formation of the functional translocon.

SUBMITTER: Basu A

PROVIDER: S-EPMC3904411 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

PcrG protects the two long helical oligomerization domains of PcrV, by an interaction mediated by the intramolecular coiled-coil region of PcrG.

Basu Abhishek A Das Urmisha U Dey Supratim S Datta Saumen S

BMC structural biology 20140124

<h4>Background</h4>PcrV is a hydrophilic translocator of type three secretion system (TTSS) and a structural component of the functional translocon. C-terminal helix of PcrV is essential for its oligomerization at the needle tip. Conformational changes within PcrV regulate the effector translocation. PcrG is a cytoplasmic regulator of TTSS and forms a high affinity complex with PcrV. C-terminal residues of PcrG control the effector secretion.<h4>Result</h4>Both PcrV and PcrG-PcrV complex exhibit ...[more]

PMID: 24460624

Similar Datasets

Project description:BackgroundThe availability of the P. falciparum genome has led to novel ways to identify potential vaccine candidates. A new approach for antigen discovery based on the bioinformatic selection of heptad repeat motifs corresponding to alpha-helical coiled coil structures yielded promising results. To elucidate the question about the relationship between the coiled coil motifs and their sequence conservation, we have assessed the extent of polymorphism in putative alpha-helical coiled coil domains in culture strains, in natural populations and in the single nucleotide polymorphism data available at PlasmoDB.Methodology/principal findings14 alpha-helical coiled coil domains were selected based on preclinical experimental evaluation. They were tested by PCR amplification and sequencing of different P. falciparum culture strains and field isolates. We found that only 3 out of 14 alpha-helical coiled coils showed point mutations and/or length polymorphisms. Based on promising immunological results 5 of these peptides were selected for further analysis. Direct sequencing of field samples from Papua New Guinea and Tanzania showed that 3 out of these 5 peptides were completely conserved. An in silico analysis of polymorphism was performed for all 166 putative alpha-helical coiled coil domains originally identified in the P. falciparum genome. We found that 82% (137/166) of these peptides were conserved, and for one peptide only the detected SNPs decreased substantially the probability score for alpha-helical coiled coil formation. More SNPs were found in arrays of almost perfect tandem repeats. In summary, the coiled coil structure prediction was rarely modified by SNPs. The analysis revealed a number of peptides with strictly conserved alpha-helical coiled coil motifs.Conclusion/significanceWe conclude that the selection of alpha-helical coiled coil structural motifs is a valuable approach to identify potential vaccine targets showing a high degree of conservation.

Dataset Information

PcrG protects the two long helical oligomerization domains of PcrV, by an interaction mediated by the intramolecular coiled-coil region of PcrG.

Publications

PcrG protects the two long helical oligomerization domains of PcrV, by an interaction mediated by the intramolecular coiled-coil region of PcrG.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets