Anchoring of LPXTG-Like Proteins to the Gram-Positive Cell Wall Envelope.
In Gram-positive bacteria, protein precursors with a signal peptide and a cell wall sorting signal (CWSS)-which begins with an LPXTG motif, followed by a hydrophobic domain and a tail of positively charged residues-are targeted to the cell envelope by a transpeptidase enzyme call sortase. Evolution and selective pressure gave rise to six classes of sortase, i.e., SrtA-F. Only class C sortases are capable of polymerizing substrates harboring the pilin motif and CWSS into protein polymers known as pili or fimbriae, whereas the others perform cell wall anchoring functions. Regardless of the products generated from these sortases, the basic principle of sortase-catalyzed transpeptidation is the same. It begins with the cleavage of the LPXTG motif, followed by the cross-linking of this cleaved product at the threonine residue to a nucleophile, i.e., an active amino group of the peptidoglycan stem peptide or the lysine residue of the pilin motif. This chapter will summarize the efforts to identify and characterize sortases and their associated pathways with emphasis on the cell wall anchoring function.
Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, TX, USA.
Sara D
SD
Siegel
Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, TX, USA.
Melissa E
ME
Reardon
Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, TX, USA. ton-that.hung@uth.tmc.edu.|Department of Microbiology and Molecular Genetics, The University of Texas Medical School at Houston, 6431 Fannin Street, MSE R213, Houston, TX, 77030, USA. ton-that.hung@uth.tmc.edu.
Hung
H
Ton-That
D020816:Amino Acid Motifs; D019881:Aminoacyltransferases / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism* / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000502:physiology; D006094:Gram-Positive Bacteria / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000502:physiology*
D001426:Bacterial Proteins; D021382:Protein Sorting Signals; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases