title: Escherichia coli HflK and HflC can individually inhibit the HflB (FtsH)-mediated proteolysis of lambdaCII in vitro.
abstract: LambdaCII is the key protein that influences the lysis/lysogeny decision of lambda by activating several phage promoters. The effect of CII is modulated by a number of phage and host proteins including Escherichia coli HflK and HflC. These membrane proteins copurify as a tightly bound complex 'HflKC' that inhibits the HflB (FtsH)-mediated proteolysis of CII both in vitro and in vivo. Individual purification of HflK and HflC has not been possible so far, since each requires the presence of the other for proper folding. We report the first purification of HflK and HflC separately as active and functional proteins and show that each can interact with HflB on its own and each inhibits the proteolysis of CII. They also inhibit the proteolysis of E. coli sigma(32) by HflB. We show that at low concentrations each protein is dimeric, based on which we propose a scheme for the mutual interactions of HflB, HflK and HflC in a supramolecular HflBKC protease complex.
authors.affiliation: Department of Biochemistry, Bose Institute P-1/12, C.I.T. Scheme VIIM, Kolkata 700 054, India.
authors.forename: Kaustav
authors.initials: K
authors.lastname: Bandyopadhyay
authors.forename: Pabitra Kumar
authors.initials: PK
authors.lastname: Parua
authors.forename: Ajit Bikram
authors.initials: AB
authors.lastname: Datta
authors.forename: Pradeep
authors.initials: P
authors.lastname: Parrack
mesh_terms: D049069:ATP-Dependent Proteases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010582:Bacteriophage lambda / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D007700:Kinetics; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D029968:Escherichia coli Proteins; C512893:HflC protein, E coli; C512891:HflK protein, E coli; D010455:Peptides; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D014764:Viral Proteins; C039000:cII protein, bacteriophage lambda; D049069:ATP-Dependent Proteases; C513383:FtsH protein, E coli