title: Identification of the putative staphylococcal AgrB catalytic residues involving the proteolytic cleavage of AgrD to generate autoinducing peptide.
abstract: The P2 operon of the staphylococcal accessory gene regulator (agr) encodes four genes (agrA, -B, -C, and -D) whose products compose a quorum sensing system: AgrA and AgrC resemble a two-component signal transduction system of which AgrC is a sensor kinase and AgrA is a response regulator; AgrD, a polypeptide that is integrated into the cytoplasmic membrane via an amphipathic alpha-helical motif in its N-terminal region, is the propeptide for an autoinducing peptide that is the ligand for AgrC; and AgrB is a novel membrane protein that involves in the processing of AgrD propeptide and possibly the secretion of the mature autoinducing peptide. In this study, we demonstrated that AgrB had endopeptidase activity, and identified 2 amino acid residues in AgrB (cysteine 84 and histidine 77) that might form a putative cysteine endopeptidase catalytic center in the proteolytic cleavage of AgrD at its C-terminal processing site. Computer analysis revealed that the cysteine and histidine residues were conserved among the potential AgrB homologous proteins, suggesting that the Agr quorum sensing system homologues might also exist in other Gram-positive bacteria.
authors.affiliation: Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
authors.forename: Rongde
authors.initials: R
authors.lastname: Qiu
authors.forename: Wuhong
authors.initials: W
authors.lastname: Pei
authors.forename: Linsheng
authors.initials: L
authors.lastname: Zhang
authors.forename: Jianqun
authors.initials: J
authors.lastname: Lin
authors.forename: Guangyong
authors.initials: G
authors.lastname: Ji
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000502:physiology*; D001665:Binding Sites; D015153:Blotting, Western; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence; D003545:Cysteine / Q000737:chemistry; D003593:Cytoplasm / Q000378:metabolism; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010456:Peptides, Cyclic; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D012984:Software; D013211:Staphylococcus aureus / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
chemical_list: C414533:AgrB protein, Staphylococcus aureus; C414532:AgrD protein, Staphylococcus; D001426:Bacterial Proteins; D017931:DNA Primers; D010455:Peptides; D010456:Peptides, Cyclic; D049452:Green Fluorescent Proteins; D006639:Histidine; D010450:Endopeptidases; D003545:Cysteine