The T4 Holin Family (TC# 1.E.8) is a group of putative pore-forming proteins that does not belong to one of the seven holin superfamilies. T-even phage such as T4 use a holin-endolysin system for host cell lysis. Although the endolysin of phage T4 encoded by the e gene (Lysozyme E) was identified in 1961, the holin (product of gene t and called T-holin) was not characterized until 2001.[1] A representative list of proteins belonging to the T4 holin family can be found in the Transporter Classification Database.[2]
Structure edit
T4 holin is fairly large, about 218 amino acyl residues (aas) in length. The protein is highly hydrophilic with 49 acidic and basic residues distributed along its length and a single putative transmembrane segment (TMS) near its N-terminus, leaving most of the protein in the periplasm.[3]
Function edit
The large periplasmic domain is a major determinant in the timing mechanism and is involved in lysis inhibition (LIN).[4] LIN involves the antiholin rI protein of T4 (See TC# 1.E.8.1.1).[5] Lysis inhibition is an effective strategy to coordinate lysis timing with phage particle maturation and to exclude other phage.[6] The C-terminal periplasmic domain of T4 holin binds the periplasmic domain of T4 antiholin (RI; 97 aas) which like the holin, spans the membrane once.[3] T-holin of T4 phage forms a 1:1 complex with the RI inhibitor which block aggregation and pore formation.[7]
Homology edit
The phage T4 T-holin (lysis protein) is identical to the holin from phage K3 and nearly identical to that from phage ARI. Residues 35-96 are 28% identical to residues 436-495 of a K+ uptake protein of Lactococcus lactis (gbAAK04721; TC# 2.A.72; KUP), suggesting an evolutionary relationship between a holin and a transporter. Holins have 1 to 4 TMSs and a short C-terminal domain rich in basic residues.
See also edit
References edit
- ^ Ramanculov, E.; Young, R. (2001-04-01). "Functional analysis of the phage T4 holin in a lambda context". Molecular Genetics and Genomics. 265 (2): 345–353. doi:10.1007/s004380000422. ISSN 1617-4615. PMID 11361346. S2CID 40455691.
- ^ "1.E.8 The T4 Holin (T4 Holin) Family". Transporter Classification Database. Retrieved 2016-03-26.
- ^ a b Tran, Tram Anh T.; Struck, Douglas K.; Young, Ry (2005-10-01). "Periplasmic domains define holin-antiholin interactions in t4 lysis inhibition". Journal of Bacteriology. 187 (19): 6631–6640. doi:10.1128/JB.187.19.6631-6640.2005. ISSN 0021-9193. PMC 1251592. PMID 16166524.
- ^ Ramanculov, E.; Young, R. (2001-03-07). "Genetic analysis of the T4 holin: timing and topology". Gene. 265 (1–2): 25–36. doi:10.1016/s0378-1119(01)00365-1. ISSN 0378-1119. PMID 11255004.
- ^ Ramanculov, E.; Young, R. (2001-08-01). "An ancient player unmasked: T4 rI encodes a t-specific antiholin". Molecular Microbiology. 41 (3): 575–583. doi:10.1046/j.1365-2958.2001.02491.x. ISSN 0950-382X. PMID 11532126. S2CID 25273199.
- ^ Miller, Eric S.; Kutter, Elizabeth; Mosig, Gisela; Arisaka, Fumio; Kunisawa, Takashi; Rüger, Wolfgang (2003-03-01). "Bacteriophage T4 genome". Microbiology and Molecular Biology Reviews. 67 (1): 86–156, table of contents. doi:10.1128/mmbr.67.1.86-156.2003. ISSN 1092-2172. PMC 150520. PMID 12626685.
- ^ Moussa, Samir H.; Kuznetsov, Vladimir; Tran, Tram Anh T.; Sacchettini, James C.; Young, Ry (2012-04-01). "Protein determinants of phage T4 lysis inhibition". Protein Science. 21 (4): 571–582. doi:10.1002/pro.2042. ISSN 1469-896X. PMC 3375757. PMID 22389108.
Further reading edit
- Catalão MJ, Gil F, Moniz-Pereira J, São-José C, Pimentel M (2013). "Diversity in bacterial lysis systems: bacteriophages show the way". FEMS Microbiology Reviews. 37 (4): 554–571. doi:10.1111/1574-6976.12006. PMID 23043507.
- Moussa SH, Lawler JL, Young R (2014). "Genetic Dissection of T4 Lysis". Journal of Bacteriology. 196 (12): 2201–2209. doi:10.1128/JB.01548-14. PMC 4054191. PMID 24706740.
- Saier MH, Reddy BL, Margolin W (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.
- Tran TA, Struck DK, Young R (2005). "Periplasmic Domains Define Holin-Antiholin Interactions in T4 Lysis Inhibition". Journal of Bacteriology. 187 (19): 6631–6640. doi:10.1128/JB.187.19.6631-6640.2005. PMC 1251592. PMID 16166524.
- Tran TA, Struck DK, Young R (2007). "The T4 RI Antiholin Has an N-Terminal Signal Anchor Release Domain That Targets It for Degradation by DegP". Journal of Bacteriology. 189 (21): 7618–7625. doi:10.1128/JB.00854-07. PMC 2168732. PMID 17693511.
- Wang IN, Smith DL, Young R (2000). "Holins: The Protein Clocks of Bacteriophage Infections". Annual Review of Microbiology. 54 (1): 799–825. doi:10.1146/annurev.micro.54.1.799. PMID 11018145.
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