Escherichia coli HflK and HflC can individually inhibit the HflB (FtsH)-mediated proteolysis of λCII in vitro

Kaustav Bandyopadhyay, Pabitra Kumar Parua, Ajit Bikram Datta, Pradeep Parrack

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


λCII is the key protein that influences the lysis/lysogeny decision of λ 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 σ32 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.

Original languageEnglish (US)
Pages (from-to)239-243
Number of pages5
JournalArchives of Biochemistry and Biophysics
Issue number2
StatePublished - Sep 2010
Externally publishedYes


  • λCII
  • HflA
  • Lysis-lysogeny decision

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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