HflD, an Escherichia coli protein involved in the lambda lysis-lysogeny switch, impairs transcription activation by lambdaCII.
The CII protein of bacteriophage lambda is the key regulator for the lytic-lysogenic choice of the viral lifecycle. An unstable homotetrameric transcription activator of the three phage promoters p(E), p(I) and p(aQ), lambdaCII is stabilized by lambdaCIII and destabilized by the host protease, Escherichia coli HflB (FtsH). In addition, other E. coli proteins HflK, HflC and HflD also influence lysogeny by acting upon CII. Among these, HflD (22.9kDa), a peripheral membrane protein that is exposed towards the cytoplasm, interacts with CII and decreases the frequency of lysogenization of lambda by stimulating the degradation of CII. In this study, we show that in addition to helping CII degradation, HflD inhibits the DNA binding by CII, thereby inhibiting CII-dependent transcription activation. From biochemical, biophysical and modelling studies we also suggest that HflD-CII interaction takes place through the Cys31-accessible surface area of monomeric HflD, which binds to tetrameric CII as a 1:1 complex.
Department of Biochemistry, Bose Institute, P-1/12, C.I.T. Scheme VIIM, Kolkata, India.
Pabitra K
PK
Parua
Avisek
A
Mondal
Pradeep
P
Parrack
D010582:Bacteriophage lambda / Q000502:physiology*; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008242:Lysogeny / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D014157:Transcription Factors; D014764:Viral Proteins
D004279:DNA, Viral; D029968:Escherichia coli Proteins; C512893:HflC protein, E coli; C427750:HflD protein, E coli; C512891:HflK protein, E coli; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D010455:Peptides; D014157:Transcription Factors; D014764:Viral Proteins; C039000:cII protein, bacteriophage lambda