Structure of sortase, the transpeptidase that anchors proteins to the cell wall of Staphylococcus aureus

doi:10.1073/pnas.101064198

Structure of sortase, the transpeptidase that anchors proteins to the cell wall of Staphylococcus aureus

^*Department of Chemistry and Biochemistry and University of California at Los Angeles-Department of Energy Laboratory of Structural Biology and Molecular Medicine, University of California, 405 Hilgard Avenue, Los Angeles, CA 90095; and ^‡Department of Microbiology and Immunology, University of California at Los Angeles School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095

Edited by Christopher T. Walsh, Harvard Medical School, Boston, MA, and approved March 13, 2001 (received for review February 7, 2001)

Abstract

Surface proteins of Gram-positive bacteria play important roles during the pathogenesis of human infections and require sortase for anchoring to the cell-wall envelope. Sortase cleaves surface proteins at the LPXTG motif and catalyzes the formation of an amide bond between the carboxyl group of threonine (T) and the amino group of cell-wall crossbridges. The NMR structure of sortase reveals a unique β-barrel structure, in which the active-site sulfhydryl of cysteine-184 is poised for ionization by histidine-120, presumably enabling the resultant thiolate to attack the LPXTG peptide. Calcium binding near the active site stimulates catalysis, possibly by altering the conformation of a surface loop that recognizes newly translocated polypeptides. The structure suggests a mechanistic relationship to the papain/cathepsin proteases and should facilitate the design of new antiinfective agents.

Footnotes

↵ † U.I. and H.T.-T. contributed equally to this work.
↵ § To whom reprint requests may be addressed. E-mail: rclubb{at}mbi.ucla.edu or olafs{at}ucla.edu.
This paper was submitted directly (Track II) to the PNAS office.
Data deposition: The atomic coordinates and structure factors have been deposited in the Protein Data Bank, www.rcsb.org (PDB ID code 1IJA).
Abbreviations:

PBP,

penicillin-binding proteins;

SrtA,

sortase;

d or Dabcyl,

4-{[4-(dimethylamino)phenyl]azo}benzoic acid;

e or Edans,

5-[(2-aminoethyl)amino]naphthalene-1-sulfonic acid