Characterization of Guided Entry of Tail-Anchored Proteins 3 Homologues in Mycobacterium tuberculosis

J Bacteriol. 2019 Jun 21;201(14):e00159-19. doi: 10.1128/JB.00159-19. Print 2019 Jul 15.

Abstract

We characterized an operon in Mycobacterium tuberculosis, Rv3679-Rv3680, in which each open reading frame is annotated to encode "anion transporter ATPase" homologues. Using structure prediction modeling, we found that Rv3679 and Rv3680 more closely resemble the guided entry of tail-anchored proteins 3 (Get3) chaperone in eukaryotes. Get3 delivers proteins into the membranes of the endoplasmic reticulum and is essential for the normal growth and physiology of some eukaryotes. We sought to characterize the structures of Rv3679 and Rv3680 and test if they have a role in M. tuberculosis pathogenesis. We solved crystal structures of the nucleotide-bound Rv3679-Rv3680 complex at 2.5 to 3.2 Å and show that while it has some similarities to Get3 and ArsA, there are notable differences, including that these proteins are unlikely to be involved in anion transport. Deletion of both genes did not reveal any conspicuous growth defects in vitro or in mice. Collectively, we identified a new class of proteins in bacteria with similarity to Get3 complexes, the functions of which remain to be determined.IMPORTANCE Numerous bacterial species encode proteins predicted to have similarity with Get3- and ArsA-type anion transporters. Our studies provide evidence that these proteins, which we named BagA and BagB, are unlikely to be involved in anion transport. In addition, BagA and BagB are conserved in all mycobacterial species, including the causative agent of leprosy, which has a highly decayed genome. This conservation suggests that BagAB constitutes a part of the core mycobacterial genome and is needed for some yet-to-be-determined part of the life cycle of these organisms.

Keywords: Get3; Mycobacterium; tuberculosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / genetics
  • Animals
  • Anion Transport Proteins / genetics
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics*
  • Female
  • Genome, Bacterial
  • Guanine Nucleotide Exchange Factors / chemistry
  • Guanine Nucleotide Exchange Factors / genetics
  • Mice
  • Mice, Inbred C57BL
  • Models, Molecular
  • Mycobacterium tuberculosis / chemistry*
  • Mycobacterium tuberculosis / genetics*
  • Operon
  • Protein Binding
  • Protein Conformation
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics

Substances

  • Anion Transport Proteins
  • Bacterial Proteins
  • Guanine Nucleotide Exchange Factors
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphatases
  • Get3 protein, S cerevisiae