- Source: Actinobacterial phage holin family
The Actinobacterial Phage Holin (APH) Family (TC# 1.E.57) is a fairly large family of proteins between 105 and 180 amino acyl residues in length, typically exhibiting a single transmembrane segment (TMS) near the N-terminus. A representative list of proteins belonging to the APH family can be found in the Transporter Classification Database.
One of the archetype proteins in this family is the Gp5 holin of mycobacteriophage Ms6. Mycobacteriophage Ms6 is a double-stranded DNA (dsDNA) bacteriophage which, in addition to the predicted endolysin (LysA)-holin (Gp4) lysis system, encodes three additional proteins within its lysis module: Gp1, LysB, and Gp5.
Ms6 Gp4 (TC# 1.E.18.1.2) was previously described as a class II holin-like protein. A second putative holin gene (gp5) encoding a protein (Gp5) with a predicted single N-terminal TMS was identified at the end of the Ms6 lytic operon. Neither the putative class II holin nor the single TMS polypeptide could trigger lysis in pairwise combinations with the endolysin LysA in Escherichia coli. However, further studies have shown that Ms6's Gp4 and Gp5 interact with each other. This suggests that in Ms6 infection, the correct and programmed timing of lysis is achieved by the combined action of Gp4 and Gp5.
See also
Actinobacteria
Holin
Lysin
Transporter Classification Database
Further reading
Petrovski, Steve; Seviour, Robert J.; Tillett, Daniel (2011). "Characterization of the Genome of the Polyvalent Lytic Bacteriophage GTE2, Which Has Potential for Biocontrol of Gordonia-, Rhodococcus-, and Nocardia-Stabilized Foams in Activated Sludge Plants". Applied and Environmental Microbiology. 77 (12): 3923–3929. Bibcode:2011ApEnM..77.3923P. doi:10.1128/AEM.00025-11. PMC 3131622. PMID 21498753.
Reddy, Bhaskara L.; Saier Jr, Milton H. (2013). "Topological and phylogenetic analyses of bacterial holin families and superfamilies". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1828 (11): 2654–2671. doi:10.1016/j.bbamem.2013.07.004. PMC 3788059. PMID 23856191.
Saier, Milton H.; Reddy, Bhaskara L. (2015). "Holins in Bacteria, Eukaryotes, and Archaea: Multifunctional Xenologues with Potential Biotechnological and Biomedical Applications". Journal of Bacteriology. 197 (1): 7–17. doi:10.1128/JB.02046-14. PMC 4288690. PMID 25157079.
Wang, I. N.; Smith, D. L.; Young, R. (2000). "Holins: the protein clocks of bacteriophage infections". Annual Review of Microbiology. 54: 799–825. doi:10.1146/annurev.micro.54.1.799. PMID 11018145.
References
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