title: Substrate recognition mechanism of the peptidase domain of the quorum-sensing-signal-producing ABC transporter ComA from Streptococcus.
abstract: ComA of Streptococcus is a member of the bacteriocin-associated ABC transporters, which is responsible for both the processing of the propeptide ComC and secretion of the mature quorum-sensing signal. The quorum-sensing system is a bacterial intercellular communication system implicated in various functions including biofilm formation. In this study, the peptidase domains (PEPs) of the ComAs from six species of Streptococcus and ComCs from four species were expressed, purified, and characterized to address the mechanism of the substrate recognition of PEP. PEPs specifically cleaved ComCs after the Gly-Gly site in all the PEP-ComC combinations examined. The N-terminal leader region of ComC was found to form an amphiphilic alpha-helix structure upon binding to the PEP. Furthermore, mutagenesis studies revealed that four conserved hydrophobic residues in this leader region of ComC extending from -15 to -4 positions are critical in the interaction with PEP. Together with the double glycine motif, these structural features of ComC would explain the strict substrate specificity of the PEP.
authors.affiliation: Department of Biochemistry, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan.
authors.forename: Yatsugu
authors.initials: Y
authors.lastname: Kotake
authors.forename: Seiji
authors.initials: S
authors.lastname: Ishii
authors.forename: Takato
authors.initials: T
authors.lastname: Yano
authors.forename: Yoji
authors.initials: Y
authors.lastname: Katsuoka
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002942:Circular Dichroism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015870:Gene Expression; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism; D011489:Protein Denaturation; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary / Q000502:physiology; D053038:Quorum Sensing; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013291:Streptococcus / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; C061262:ComA protein, Bacteria; D004268:DNA-Binding Proteins; C423628:competence factor, Streptococcus; D010447:Peptide Hydrolases