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PMID:11459934

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Citation

Gründling, A, Manson, MD and Young, R (2001) Holins kill without warning. Proc. Natl. Acad. Sci. U.S.A. 98:9348-52

Abstract

Holins comprise the most diverse functional group of proteins known. They are small bacteriophage-encoded proteins that accumulate during the period of late-protein synthesis after infection and cause lysis of the host cell at a precise genetically programmed time. It is unknown how holins achieve temporal precision, but a conserved feature of their function is that energy poisons subvert the normal scheduling mechanism and instantly trigger membrane disruption. On this basis, timing has been proposed to involve a progressive decrease in the energized state of the membrane until a critical triggering level is reached. Here, we report that membrane integrity is not compromised after the induction of holin synthesis until seconds before lysis. The proton motive force was monitored by the rotation of individual cells tethered by a single flagellum. The results suggest an alternative explanation for the lysis "clock," in which holin concentrations build to a critical level that leads to formation of an oligomeric complex that disrupts the membrane.

Links

PubMed PMC55423 Online version:10.1073/pnas.151247598

Keywords

Bacteriophages/metabolism; Escherichia coli/virology; Muramidase/metabolism; Viral Proteins/physiology

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

BPT4:HOLIN

GO:0034291: canonical holin activity

ECO:0000314: direct assay evidence used in manual assertion

F

Figure 2 shows the microscopic images of the bacterial cells pre and post induction of the Lambda lysis genes. Before the induction of the lysis genes, there was an abundant amount of bacterial cells present. After 25 minutes of the induction of the Lambda lysis genes, the amount of bacterial cells significantly decreased, showing that the cells were broken apart and lysed.

complete
CACAO 12881


See also

References

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