PMID:17693511

Citation	Tran, TA, Struck, DK and Young, R (2007) The T4 RI antiholin has an N-terminal signal anchor release domain that targets it for degradation by DegP. J. Bacteriol. 189:7618-25
Abstract	Lysis inhibition (LIN) of T4-infected cells was one of the foundational experimental systems for modern molecular genetics. In LIN, secondary infection of T4-infected cells results in a dramatically protracted infection cycle in which intracellular phage and endolysin accumulation can continue for hours. At the molecular level, this is due to the inhibition of the holin, T, by the antiholin, RI. RI is only 97 residues and contains an N-terminal hydrophobic domain and a C-terminal hydrophilic domain; expression of the latter domain fused to a secretory signal sequence is sufficient to impose LIN, due to its specific interaction with the periplasmic domain of the T holin. Here we show that the N-terminal sequence comprises a signal anchor release (SAR) domain, which causes the secretion of RI in a membrane-tethered form and then its subsequent release into the periplasm, without proteolytic processing. Moreover, the SAR domain confers both functional lability and DegP-mediated proteolytic instability on the released form of RI, although LIN is not affected in a degP host. These results are discussed in terms of a model for the activation of RI in the establishment of the LIN state.
Links	PubMed PMC2168732 Online version:10.1128/JB.00854-07
Keywords	Amino Acid Sequence; Bacteriophage T4/genetics; Bacteriophage T4/physiology; Escherichia coli/enzymology; Escherichia coli/genetics; Heat-Shock Proteins/genetics; Heat-Shock Proteins/metabolism; Kinetics; Molecular Sequence Data; Peptide Fragments/metabolism; Periplasmic Proteins/genetics; Periplasmic Proteins/metabolism; Serine Endopeptidases/genetics; Serine Endopeptidases/metabolism; Signal Transduction; Viral Proteins/genetics; Viral Proteins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPT4:VR1		GO:0001899: negative regulation of cytolysis by symbiont of host cells	ECO:0000315:		P		Figure 3. Shows loss of rI function results in earlier lysis of host cells. NOTE: this GO-term is not completely accurate. A new GO-term has been requested. While "GO:1901218 - negative regulation of holin activity" already exists, and is accurate to the function of this protein, this paper does not specifically show it is interacting with a holin. This paper only shows rI negatively regulates cytolysis of its host. NTR: negative regulation of cytolysis by virus of host cells	complete CACAO 10414
BPT4:VR1	part_of	GO:0020002: host cell plasma membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
BPT4:ANTIH		GO:0020002: host cell plasma membrane	ECO:0000314:		C		Figure 2.	complete CACAO 10413
BPT4:ANTIH	part_of	GO:0020002: host cell plasma membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete

References

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