Holin

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]

  1. ^ 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.
  2. ^ 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.
  3. ^ Young R (January 2002). "Bacteriophage Holins: Deadly Diversity" (PDF). J. Mol. Microbiol. Biotechnol. 4 (1): 21–36. PMID 11763969.
  4. ^ 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.
  5. ^ 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.
  6. ^ 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.
  7. ^ 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.