PMID:11361346

Citation	Ramanculov, E and Young, R (2001) Functional analysis of the phage T4 holin in a lambda context. Mol. Genet. Genomics 265:345-53
Abstract	Phage lambda hybrids were constructed by inserting the t gene of phage T4 in place of the lambda holin gene, S. Induction of the hybrid phage resulted in lysis that was just as abrupt as, but occurred much earlier in the vegetative cycle than, that obtained with lambda, indicating that t is indeed a holin gene. Moreover, it was possible to impose lysis inhibition (LIN) on induction of the hybrid phage, but not of the parental lambda phage, by superinfection with LIN-competent T4. The imposition of the LIN state was found to depend on the allelic state of the rI and t genes of the superinfecting T4 phage, indicating that the LIN-sensitive state of the T holin is transient. Finally, induction of lysogens carrying both holin genes was shown to result in earlier triggering of lysis than with either holin gene alone. This result suggests that the two very dissimilar holins contribute additively to the physiology of the timing mechanism, or, less likely, that they interact to form one mass-action pool. In either case, these results imply a common pathway for holin timing and function.
Links	PubMed Full Text
Keywords	Amino Acid Sequence; Bacteriophage T4/genetics; Bacteriophage lambda/genetics; Molecular Sequence Data; Viral Proteins/genetics; Viral Proteins/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
LAMBD:VLYS	enables	GO:0034291: canonical holin activity	ECO:0000315: mutant phenotype evidence used in manual assertion		F		Seeded From UniProt	complete
LAMBD:HOLIN	enables	GO:0034291: canonical holin activity	ECO:0000315: mutant phenotype evidence used in manual assertion		F		Seeded From UniProt	complete
LAMBD:HOLIN		GO:0034291: canonical holin activity	ECO:0000315:		F		Figure 2A. Shows a deletion of S fails to yield induction of lysis in the host. The figure also shows the presence of S restores this activity. Paper states S is a holin.	complete CACAO 10420
BPT4:VR1		GO:0001899: negative regulation of cytolysis by symbiont of host cells	ECO:0000315:		P		Figure 4. shows loss in the function of rI results in an earlier lysis of cell. NOTE - Go - Term requested. NTR: negative regulation of cytolysis by virus of host cells	complete CACAO 10423
BPT4:VR1	involved_in	GO:1901218: negative regulation of holin activity	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
BPT4:ANTIH		GO:1901218: negative regulation of holin activity	ECO:0000315:		P		Lambda T4 phage lacking an effective rI allele show earlier lysis phenotypes compared to wild type lambda T4 phage (Figure 5B).	complete CACAO 10693
BPT4:ANTIH	involved_in	GO:1901218: negative regulation of holin activity	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
BPT1:SPANU		GO:0034291: canonical holin activity		UniProtKB:P03705	F		Figure 2A. and Figure 2B. show that the T4 protein "t" can complement the function of Lambda "S" holin gene.	Missing: evidence CACAO 10421

References

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