Holins are a diverse group of small proteins produced by dsDNA bacteriophages in order to trigger and control the degradation of the host's cell wall at the end of the lytic cycle. Holins form pores in the host's cell membrane, allowing lysins to reach and degrade peptidoglycan, a component of bacterial cell walls. Holins have been shown to regulate the timing of lysis with great precision.[1] Over 50 unrelated gene families encode holins, making them the most diverse group of proteins with common function.[2][3] Together with lysins, holins are being studied for their potential use as antibacterial agents.[4]
While canonical holins act by forming large pores, pinholins such as the S protein of lambdoid phage 21 act by forming heptameric channels that depolarize the bacterial membrane. They are associated with SAR endolysins, which remain inactive in the periplasm prior to the depolarization of the membrane.[5]
Viruses that infect eukaryotic cells may use similar channel-forming proteins called viroporins.[6][7]
^Wang IN, Smith DL, Young R (2002). "Holins: the protein clocks of bacteriophage infections". Annu Rev Microbiol. 54: 799–825. doi:10.1146/annurev.micro.54.1.799. PMID 11018145.
^Gründling A, Manson MD, Young R (July 2001). "Holins kill without warning". Proc. Natl. Acad. Sci. U.S.A. 98 (16): 9348–9352. doi:10.1073/pnas.151247598. PMC 55423. PMID 11459934.
^Young R (January 2002). "Bacteriophage Holins: Deadly Diversity" (PDF). J. Mol. Microbiol. Biotechnol. 4 (1): 21–36. PMID 11763969.
^Veiga-Crespo P; Barros-Velázquez J; Villa T.G. (2007). Méndez-Vilas A (ed.). "What can bacteriophages do for us?" (PDF). Communicating Current Research and Educational Topics and Trends in Applied Microbiology: 885–893. Archived from the original (PDF) on 2016-03-03. Retrieved 2013-11-09.
^Young, Ryland (1 March 2014). "Phage lysis: Three steps, three choices, one outcome". Journal of Microbiology. 52 (3): 243–258. doi:10.1007/s12275-014-4087-z. PMC 4012431. PMID 24585055.
^Nieva, José Luis; Madan, Vanesa; Carrasco, Luis (2 July 2012). "Viroporins: structure and biological functions". Nature Reviews Microbiology. 10 (8): 563–574. doi:10.1038/nrmicro2820. hdl:10261/115331. PMC 7097105. PMID 22751485.
^Nieva, José; Carrasco, Luis (29 September 2015). "Viroporins: Structures and functions beyond cell membrane permeabilization". Viruses. 7 (10): 5169–5171. doi:10.3390/v7102866. PMC 4632374. PMID 26702461.
of seven holin superfamilies. Holin superfamily I Holin superfamily II Holin superfamily III Holin superfamily IV Holin superfamily V Holin superfamily...
Batia Holin (Hebrew: בתיה הולין; née: Cahana born 22 January 1953) is an Israeli photographer and social activist. Holin was born in 1953 in Holon to Levi...
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...
The Enterobacterial Holin (EBHol) Family (TC# 1.E.48) consists of many closely related proteins of 100 to 120 amino acyl residues (aas) in length with...
The Firmicute Phage φU53 Holin (φU53 Holin) Family (TC# 1.E.13) consists of putative holins that range in size from 117 to 124 amino acyl residues (aas)...
Vibrio Holin family can be found in the Transporter Classification Database. Holin Lysin Transporter Classification Database "1.E.30 The Vibrio Holin (Vibrio...
individual members. The Holin superfamily VI includes two TC families: 1.E.12 - The φAdh Holin (φAdh Holin) Family 1.E.26 - The Holin LLH (Holin LLH) Family Superfamily...
Phi11 Holin (φ11 Holin) Family (TC# 1.E.11) constitutes the Holin Superfamily I. One characterized member of this family, pneumococcal EJ-1 phage holin (EJh;...
The T7 Holin family (TC# 1.E.6) is a member of the Holin Superfamily II. Members of this family are predominantly found in Caudovirales and Pseudomonadota...
The Pseudomonas phage F116 holin is a non-characterized holin homologous to one in Neisseria gonorrheae that has been characterized. This protein is the...
The holin LLH family (TC# 1.E.26) is a group of transporters belonging to the Holin superfamily VI. The Holin LLH family is found in Bacillota and phage...
The Putative Listeria Phage Holin (LP-Hol) Family (TC# 1.E.51) consists of several small proteins of 41 amino acyl residues (aas) and 1 transmembrane...
of lysis is determined by the holin and antiholin proteins, with the latter inhibiting the former. In overview, the holin protein accumulates in the cytoplasmic...
The BhlA Holin Family (TC# 1.E.27) is named after putative holin-like peptides encoded in bacteria with bacteriocin similarities. BhlA proteins are generally...
The LydA Holin (LydA Holin) Family (TC# 1.E.4), named after the lydA gene which codes for its prototype member (LydA of E. coli; TC# 1.E.4.1.1), belongs...
The Holin superfamily IV includes the TC families: 1.E.10 - The Bacillus subtilis φ29 Holin (φ29 Holin) Family 1.E.16 - The Cph1 Holin (Cph1 Holin) Family...
The SPP1 Holin (SPP1 Holin) Family (TC# 1.E.31) consists of proteins of between 90 and 160 amino acyl residues (aas) in length that exhibit two transmembrane...
The ArpQ Holin (ArpQ Holin) Family (TC# 1.E.15) consists of a single holin-like protein 58 amino acyl residues (aas) in length with 2 transmembrane segments...
The Brachyspira holin (B-Hol) Family (TC# 1.E.55) consists of several proteins from the GTA holin of Brachyspira hyodysenteriae (TC# 1.E.55.1.1), which...
The λ Holin S (λ Holin) Family 1.E.3 - The P2 Holin (P2 Holin) Family 1.E.4 - The LydA Holin (LydA Holin) Family 1.E.5 - The PRD1 Phage P35 Holin (P35...
The Lactococcus lactis Phage r1t Holin (r1t Holin) Family (TC# 1.E.18) is a family of putative pore-forming proteins that typically range in size between...
The Holin Superfamily I (aka the CDD phage holin1 superfamily) is a superfamily of integral membrane transport proteins. It is one of the seven different...
The Lambda Holin S (λ Holin) Family (TC# 1.E.2) is a group of integral membrane transporter proteins belonging to the Holin Superfamily III. Members of...
The β-proteobacterial holin (BP-Hol) family (TC# 1.E.50) is a small family that includes members derived from a number of Burkholderia phage as well as...
The HP1 Holin (HP1 Holin) Family (TC# 1.E.7 ) is a member of the Holin Superfamily II. Proteins in this family are typically found to contain two transmembrane...
The Clostridium difficile TcdE Holin (TcdE Holin) Family (TC# 1.E.19) is a group of transporters belonging to the Holin Superfamily IV. A representative...
The Putative Bacterial Archaeal Holin (BAH) Family (TC# 9.B.185) consists of several uncharacterized proteins. However, these proteins were retrieved...
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