\"BACKGROUND: The lysis-lysogeny decision in the temperate coliphage is influenc

Question

"BACKGROUND: The lysis-lysogeny decision in the temperate coliphage 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 infects hflKC cells, turbid plaques are produced, indicating stabilization of CII under these conditions. RESULTS: We find that CII is stabilized in hflKC cells even without infection by , if CIII is present. Nevertheless, we also obtained turbid plaques when a hflKC host was infected by a cIII-defective phage (cIII67). 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 hflKC cells even in the absence of CIII, leading to lysogeny. CONCLUSION: We propose that a yet unidentified CII-stabilizing factor in may influence the lysis-lysogeny decision in hflKC cells. " In a separate study, authors showed that deletion of FtsH restores CII following heat induction, but not following SOS (DNA damage) induction.

Question?

In a separate study, authors showed that deletion of FtsH restores CII following heat induction, but not following SOS (DNA damage) induction.

Would you expect CII to be stabilized or activated during DNA damage? Briefly explain why.

Explanation / Answer

From the given understanding, I would expect CII to be not stabilized during DNA damage. This is because then SOS repair would be induced which will interfere with CII stabilization. It may thus activate it. Here, I would like to say that heat induction doesn’t damage DNA, it only denatures it, thus, not activating SOS repair.

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