Sorting sortases: a nomenclature proposal for the various sortases of Gram-positive bacteria

Res Microbiol. 2005 Apr;156(3):289-97. doi: 10.1016/j.resmic.2004.10.011. Epub 2005 Jan 28.


Bacterial surface proteins constitute a diverse group of molecules with important functions, such as adherence, invasion, signaling and interaction with the host immune system or the environment. In Gram-positive bacteria, many surface proteins are anchored to the cell wall envelope by an enzyme named sortase, which recognizes a conserved carboxylic sorting motif. The sequence of the prototype staphylococcal SrtA has been widely used to identify homologs in bacterial genomes, revealing a profusion of sortases in almost all Gram-positive bacteria, often with more than one sortase-like protein per genome [M.J. Pallen, A.C. Lam, M. Antonio, K. Dunbar, Trends Microbiol. 9 (2001) 97-102]. In light of increasing reports on the identification and/or characterization of paralogous sortase genes, a classification of sortases now appears necessary. This report provides an analysis of sixty-one sortases from complete Gram-positive genomes, and suggests the existence of four structural groups of sortases. We propose the classification of sortases into 4 classes designated A, B, C and D. This classification should help to discriminate between sortases in the future.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Sequence
  • Aminoacyltransferases / classification*
  • Aminoacyltransferases / genetics
  • Bacterial Proteins
  • Cluster Analysis
  • Cysteine Endopeptidases
  • Genome, Bacterial
  • Gram-Positive Bacteria / enzymology*
  • Gram-Positive Bacteria / genetics
  • Molecular Sequence Data
  • Phylogeny
  • Terminology as Topic*


  • Bacterial Proteins
  • Aminoacyltransferases
  • sortase A
  • Cysteine Endopeptidases