Studies on Escherichia coliHflKC suggest the presence of an unidentified λ factor that influences the lysis-lysogeny switch

Abstract

BackgroundThe lysis-lysogeny decision in the temperate coliphage λ is influenced by a number of phage proteins (CII and CIII) as well as host factors, viz. Escherichia coli HflB, HflKC and HflD. Prominent among these are the transcription factor CII and HflB, an ATP-dependent protease that degrades CII. Stabilization of CII promotes lysogeny, while its destabilization induces the lytic mode of development. All other factors that influence the lytic/lysogenic decision are known to act by their effects on the stability of CII. Deletion of hflKC has no effect on the stability of CII. However, when λ infects ΔhflKC cells, turbid plaques are produced, indicating stabilization of CII under these conditions.ResultsWe find that CII is stabilized in ΔhflKC cells even without infection by λ, if CIII is present. Nevertheless, we also obtained turbid plaques when a ΔhflKC host was infected by a cIII-defective phage (λcIII67). This observation raises a fundamental question: does lysogeny necessarily correlate with the stabilization of CII? Our experiments indicate that CII is indeed stabilized under these conditions, implying that stabilization of CII is possible in ΔhflKC cells even in the absence of CIII, leading to lysogeny.ConclusionWe propose that a yet unidentified CII-stabilizing factor in λ may influence the lysis-lysogeny decision in ΔhflKC cells.

Two Inducible Prophages of an Antarctic Pseudomonas sp. ANT_H14 Use the Same Capsid for Packaging Their Genomes – Characterization of a Novel Phage Helper-Satellite System

“…The E . coli membrane proteins HflK and HflC form a complex HflKC that was found to act as a modulator of the HflB(FtsH)-mediated proteolysis of λ CII, which is the key element regulating the switch between lytic and lysogenic lifecycle through the activation of several phage λ promoters [ 63 ].…”

Diversity, evolution and life strategies of CbK‐like phages

“…Multiple lysogeny‐related genes are a common feature of CbK‐like phages, and a total of six related genes were found (Figure 5), including genes encoding FimE‐like and Cre‐like recombinases, a lexA ‐like repressor gene, a tandem array of rIIA and rIIB genes involved in lysis inhibition (Benzer, 1955) and high frequency of lysogenization K ( hflK ) participated in lysogeny control (Bandyopadhyay et al, 2011). Except for the gene encoding Cre‐like recombinase, the other five lysogeny‐related genes are distributed to varying degrees among the two clades.…”

Burkholderia contaminans Bacteriophage CSP3 Requires O-Antigen Polysaccharides for Infection

“…HlfC is a part of the hfl locus that modulates the lifestyle of lambda phage. HflC, along with HflK, forms a protein complex that modulates the activity of HflB, which directly inhibits lambda phage protein CII, which drives the lysogenic life cycle ( 47 ). Therefore, the presence of phage-encoded HlfC could help drive lysogeny in CSP3.…”