Prediction of Burkholderia pseudomallei DsbA substrates identifies potential virulence factors and vaccine targets

PLoS One. 2020 Nov 20;15(11):e0241306. doi: 10.1371/journal.pone.0241306. eCollection 2020.

Abstract

Identification of bacterial virulence factors is critical for understanding disease pathogenesis, drug discovery and vaccine development. In this study we used two approaches to predict virulence factors of Burkholderia pseudomallei, the Gram-negative bacterium that causes melioidosis. B. pseudomallei is naturally antibiotic resistant and there are no clinically available melioidosis vaccines. To identify B. pseudomallei protein targets for drug discovery and vaccine development, we chose to search for substrates of the B. pseudomallei periplasmic disulfide bond forming protein A (DsbA). DsbA introduces disulfide bonds into extra-cytoplasmic proteins and is essential for virulence in many Gram-negative organism, including B. pseudomallei. The first approach to identify B. pseudomallei DsbA virulence factor substrates was a large-scale genomic analysis of 511 unique B. pseudomallei disease-associated strains. This yielded 4,496 core gene products, of which we hypothesise 263 are DsbA substrates. Manual curation and database screening of the 263 mature proteins yielded 81 associated with disease pathogenesis or virulence. These were screened for structural homologues to predict potential B-cell epitopes. In the second approach, we searched the B. pseudomallei genome for homologues of the more than 90 known DsbA substrates in other bacteria. Using this approach, we identified 15 putative B. pseudomallei DsbA virulence factor substrates, with two of these previously identified in the genomic approach, bringing the total number of putative DsbA virulence factor substrates to 94. The two putative B. pseudomallei virulence factors identified by both methods are homologues of PenI family β-lactamase and a molecular chaperone. These two proteins could serve as high priority targets for future B. pseudomallei virulence factor characterization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / metabolism*
  • Bacterial Vaccines / immunology*
  • Burkholderia pseudomallei / genetics
  • Burkholderia pseudomallei / immunology*
  • Burkholderia pseudomallei / pathogenicity*
  • Cysteine / metabolism
  • Epitopes, B-Lymphocyte / chemistry
  • Epitopes, B-Lymphocyte / immunology
  • Gene Ontology
  • Genome, Bacterial
  • Models, Molecular
  • Sequence Homology, Amino Acid
  • Substrate Specificity
  • Virulence Factors / metabolism*

Substances

  • Bacterial Proteins
  • Bacterial Vaccines
  • Epitopes, B-Lymphocyte
  • Virulence Factors
  • Cysteine

Grants and funding

This work was supported by an Australian National Health and Medical Research Council (www.nhmrc.gov.au) Project Grant (GRT1144046) to JLM; GAP and MAH were also supported by this award. BV was in receipt of a Research Fellowship from Griffith University. GAP is supported by a Griffith University Post-Graduate Research Scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.