PE is a functional domain responsible for protein translocation and localization on mycobacterial cell wall

Mol Microbiol. 2007 Dec;66(6):1536-47. doi: 10.1111/j.1365-2958.2007.06023.x. Epub 2007 Nov 19.

Abstract

The PE family of Mycobacterium tuberculosis includes 98 proteins which share a highly homologous N-terminus sequence of about 110 amino acids (PE domain). Depending on the C-terminal domain, the PE family can be divided in three subfamilies, the largest of which is the PE_PGRS with 61 members. In this study, we determined the cellular localization of three PE proteins by cell fractionation and immunoelectron microscopy by expressing chimeric epitope-tagged recombinant proteins in Mycobacterium smegmatis. We demonstrate that the PE domain of PE_PGRS33 and PE11 (a protein constituted by the only PE domain) contains the information necessary for cell wall localization, and that they can be used as N-terminal fusion partners to deliver a sufficiently long C-terminus-linked protein domain on the mycobacterial cell surface. Indeed, we demonstrate that PE_PGRS33 and Rv3097c (a lipase belonging to the PE family) are surface exposed and localize in the mycobacterial cell wall. Moreover, we found that PE_PGRS33 is easily extractable by detergents suggesting its localization in the mycobacterial outer membrane. Beyond defining the cellular localization of these proteins, and a function for their PE domains, these data open the interesting possibility to construct recombinant mycobacteria expressing heterologous antigens on their surface for vaccine purposes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • Blotting, Western
  • Cell Wall / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • Endopeptidase K / metabolism
  • Gene Expression Regulation, Bacterial
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Microscopy, Immunoelectron
  • Mycobacterium smegmatis / genetics
  • Mycobacterium smegmatis / metabolism*
  • Mycobacterium smegmatis / ultrastructure
  • Protein Transport
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*

Substances

  • Bacterial Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • Endopeptidase K