P35 holin family

The PRD1 Phage P35 Holin (P35 Holin) Family (TC# 1.E.5) is a member of Holin Superfamily III.[1] The prototype for this family is the lipid-containing PRD1 enterobacterial phage holin protein P35 (12.8 kDa; TC# 1.E.5.1.1) encoded by gene XXXV (orfT).[2] It is a component of a typical holin-endolysin system which functions to lyse the host bacterial cell.

Structure

P35 holin (TC# 1.E.5.1.1) has 3 transmembrane segments (TMSs) with 5 positively charged residues between TMSs 1 and 2. It has 4 positively charged residues at the C-terminus.[2] It is therefore thought that the N-terminus is in the periplasm and the C-terminus is in the cytoplasm. Homologues of 109 amino acyl residues (aas), which also have 3 putative TMSs, are encoded in the genomes of Xylella fastidiosa strains.[2]

Function

PRD1 infects gram-negative cells harboring a conjugative IncP plasmid. Progeny phage particles are released from the host cell via a two-component lysis system (holin-endolysin). Ziedaite et al. (2005) monitored the ion flux and ATP content of infected cells to set up a model of the sequence of lysis-related physiological changes in the infected host. They showed a decrease in the intracellular level of ATP is the earliest indicator of cell lysis, followed by the leakage of K+ from the cytosol approximately 20 minutes prior to the decrease in culture turbidity. However, the K+ efflux did not immediately lead to the depolarization of the cytoplasmic membrane or leakage of the intracellular ATP. These effects were observed only approximately 5 to 10 minutes prior to cell lysis.[3] Similar results were obtained using cells expressing the holin and endolysin genes from plasmids.

The reaction catalyzed by P35 holin is:

autolysin (in) → autolysin (out)

See also

References

  1. ↑ Reddy, Bhaskara L.; Saier, Milton H. (2013-11-01). "Topological and phylogenetic analyses of bacterial holin families and superfamilies". Biochimica et Biophysica Acta. 1828 (11): 2654–2671. doi:10.1016/j.bbamem.2013.07.004. ISSN 0006-3002. PMC 3788059Freely accessible. PMID 23856191.
  2. 1 2 3 Rydman, Pia S.; Bamford, Dennis H. (2003-07-01). "Identification and mutational analysis of bacteriophage PRD1 holin protein P35". Journal of Bacteriology. 185 (13): 3795–3803. doi:10.1128/jb.185.13.3795-3803.2003. ISSN 0021-9193. PMC 161566Freely accessible. PMID 12813073.
  3. ↑ Žiedaitė, Gabija; Daugelavičius, Rimantas; Bamford, Jaana K. H.; Bamford, Dennis H. (2005-08-01). "The Holin Protein of Bacteriophage PRD1 Forms a Pore for Small-Molecule and Endolysin Translocation". Journal of Bacteriology. 187 (15): 5397–5405. doi:10.1128/JB.187.15.5397-5405.2005. ISSN 0021-9193. PMC 1196050Freely accessible. PMID 16030234.

As of 10 March 2016, this article is derived in whole or in part from Transporter Classification Database (TCDB). The copyright holder has licensed the content in a manner that permits reuse under CC BY-SA 3.0 and GFDL. All relevant terms must be followed. The original text was at "1.E.5 The PRD1 Phage P35 Holin (P35 Holin) Family".


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