Structure-function analysis of PrsA reveals roles for the parvulin-like and flanking N- and C-terminal domains in protein folding and secretion in Bacillus subtilis

J Biol Chem. 2004 Apr 30;279(18):19302-14. doi: 10.1074/jbc.M400861200. Epub 2004 Feb 19.

Abstract

The PrsA protein of Bacillus subtilis is an essential membrane-bound lipoprotein that is assumed to assist post-translocational folding of exported proteins and stabilize them in the compartment between the cytoplasmic membrane and cell wall. This folding activity is consistent with the homology of a segment of PrsA with parvulin-type peptidyl-prolyl cis/trans isomerases (PPIase). In this study, molecular modeling showed that the parvulin-like region can adopt a parvulin-type fold with structurally conserved active site residues. PrsA exhibits PPIase activity in a manner dependent on the parvulin-like domain. We constructed deletion, peptide insertion, and amino acid substitution mutations and demonstrated that the parvulin-like domain as well as flanking N- and C-terminal domains are essential for in vivo PrsA function in protein secretion and growth. Surprisingly, none of the predicted active site residues of the parvulin-like domain was essential for growth and protein secretion, although several active site mutations reduced or abolished the PPIase activity or the ability of PrsA to catalyze proline-limited protein folding in vitro. Our results indicate that PrsA is a PPIase, but the essential role in vivo seems to depend on some non-PPIase activity of both the parvulin-like and flanking domains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus subtilis / chemistry*
  • Bacillus subtilis / metabolism
  • Bacterial Proteins / chemistry
  • Catalytic Domain
  • Lipoproteins / chemistry*
  • Lipoproteins / genetics
  • Lipoproteins / physiology*
  • Membrane Proteins / chemistry*
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Mutagenesis, Site-Directed
  • NIMA-Interacting Peptidylprolyl Isomerase
  • Peptidylprolyl Isomerase / chemistry
  • Protein Folding*
  • Protein Structure, Tertiary
  • Proteins / metabolism*

Substances

  • Bacterial Proteins
  • Lipoproteins
  • Membrane Proteins
  • NIMA-Interacting Peptidylprolyl Isomerase
  • Proteins
  • prsA protein, bacteria
  • Peptidylprolyl Isomerase