Targeting of muralytic enzymes to the cell division site of Gram-positive bacteria: repeat domains direct autolysin to the equatorial surface ring of Staphylococcus aureus.
Staphylococcus aureus secretes autolysin (Atl) to complete cell division by hydrolyzing its thick cell wall layer at a designated site, known as the equatorial surface ring. Secreted pro-Atl (1256 amino acids) is cleaved at residues 198 and 775 to generate a pro-peptide, amidase and glucosaminidase, respectively. Here we examined the mechanism that directs amidase and glucosaminidase to the cell division site on the staphylococcal surface. Targeting of pro-Atl to the cell surface occurred prior to its proteolytic processing. Three repeat domains (R1, R2 and R3) located at the center of pro-Atl are necessary and sufficient for the targeting of reporter proteins to the equatorial surface ring. Pro-Atl cleavage at residue 775 separates the polypeptide such that R1 and R2 are linked to the C-terminus of amidase, whereas R3 is located at the N-terminus of glucosaminidase. Thus, it appears that the repeat domains direct pro-Atl, amidase and glucosaminidase to a specific receptor at the equatorial surface ring of staphylococci, thereby allowing localized peptidoglycan hydrolysis and separation of the dividing cells.
Baba
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Department of Microbiology and Immunology, UCLA School of Medicine, University of California, Los Angeles, CA 90095, USA.
Schneewind
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D001483:Base Sequence; D002455:Cell Division; D017931:DNA Primers; D004768:Enterotoxins / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013211:Staphylococcus aureus / Q000166:cytology / Q000201:enzymology*
D017931:DNA Primers; D004768:Enterotoxins; D011993:Recombinant Fusion Proteins; C031818:enterotoxin B, staphylococcal; D005982:Glutathione Transferase; D009238:N-Acetylmuramoyl-L-alanine Amidase