PMID:22904283

Citation	Berry, J, Rajaure, M, Pang, T and Young, R (2012) The spanin complex is essential for lambda lysis. J. Bacteriol. 194:5667-74
Abstract	Phage lysis is a ubiquitous biological process, the most frequent cytocidal event in the biosphere. Lysis of Gram-negative hosts has been shown to require holins and endolysins, which attack the cytoplasmic membrane and peptidoglycan, respectively. Recently, a third class of lysis proteins, the spanins, was identified. The first spanins to be characterized were λ Rz and Rz1, an integral cytoplasmic membrane protein and an outer membrane lipoprotein, respectively. Previous work has shown that Rz and Rz1 form complexes that span the entire periplasm. Phase-contrast video microscopy was used to record the morphological changes involved in the lysis of induced λ lysogens carrying prophages with either the λ canonical holin-endolysin system or the phage 21 pinholin-signal anchor release (SAR) endolysin system. In the former, rod morphology persisted until the instant of an explosive polar rupture, immediately emptying the cell of its contents. In contrast, in pinholin-SAR endolysin lysis, the cell began to shorten and thicken uniformly, with the resultant rounded cell finally bursting. In both cases, lysis failed to occur in inductions of isogenic prophages carrying null mutations in the spanin genes. In both systems, instead of an envelope rupture, the induced cells were converted from a rod shape to a spherical form. A functional GFPΦRz chimera was shown to exhibit a punctate distribution when coexpressed with Rz1, despite the absence of endolysin function. A model is proposed in which the spanins carry out the essential step of disrupting the outer membrane, in a manner regulated by the state of the peptidoglycan layer.
Links	PubMed PMC3458670 Online version:10.1128/JB.01245-12
Keywords	Bacteriolysis; Bacteriophage lambda/enzymology; Bacteriophage lambda/genetics; Bacteriophage lambda/physiology; Endopeptidases/genetics; Endopeptidases/metabolism; Gene Deletion; Lysogeny; Microscopy, Phase-Contrast; Microscopy, Video; Models, Biological; Viral Proteins/genetics; Viral Proteins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
LAMBD:SPAN2		GO:0090680: disruption by virus of host outer membrane	ECO:0000315:		P		Fig. 2a,b,e and f demonstrates that Rz1, a spanin outer lipoprotein subunit of the Escherichia phage lambda is essential part of the RzRz1 spanin complex, which rapidly lyses the E. coli bacterium. When mutant was observed, the outer membrane was not ruptured, preventing lysis of the bacterium.	complete CACAO 13416
LAMBD:SPAN1		GO:0090680: disruption by virus of host outer membrane	ECO:0000315:		P		Fig. 2a,b,e and f demonstrates that Rz, a spanin inner membrane subunit of the Escherichia phage lambda is essential part of the RzRz1 spanin complex, which rapidly lyses the E. coli bacterium. When mutant was observed, the outer membrane was not ruptured, preventing lysis of the bacterium.	complete CACAO 13412
BPP21:SPAN1		GO:0090680: disruption by virus of host outer membrane	ECO:0000315:		P		Fig. 2c,d,g and h demonstrates that Rz, a spanin inner membrane subunit of the Enterobacteria phage P21 is essential part of the RzRz1 spanin complex, which rapidly lyses the E. coli bacterium. When mutant was observed, the outer membrane was not ruptured, preventing lysis of the bacterium.	complete CACAO 13417

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