A cytoplasmic antiholin is embedded in-frame with the holin in a Lactobacillus fermentum bacteriophage.

A cytoplasmic antiholin is embedded in-frame with the holin in a Lactobacillus fermentum bacteriophage. Appl Environ Microbiol. 2018 Jan 05;: Authors: Guo T, Xin Y, Zhang C, Kong J Abstract In double-stranded DNA bacteriophages, infection cycles are ended by host cell lysis through the action of phage-encoded endolysins and holins. The precise timing of lysis is regulated by the holin inhibitors, named antiholins. Sequence analysis has revealed that holins with a single transmembrane domain (TMD) are prevalent in Lactobacillus bacteriophages. A temperate bacteriophage of Lbfermentum, Ď•PYB5, has a two-component lysis cassette containing endolysin Lyb5 and holin Hyb5. The hyb5 gene is 465-bp long, encoding 154 amino acid residues with an N-terminal TMD and a large cytoplasmic C-terminal domain. However, the N-terminus contains no dual-start-motif, suggesting that Hyb5 oligomerization could be inhibited by a specific antiholin. Two internal open reading frames in hyb5, hyb5157-465 and hyb5209-328, were identified as putative antiholins for Hyb5, and co-expressed in trans with lyb5-hyb5 in Escherichia coli Surprisingly, host cell lysis was delayed by Hyb5157-465, but accelerated by abolishment of the translation initiation site of this protein, indicating that Hyb5157-465 acts as an antiholin to holin Hyb5. Moreover, deletion of 45 amino acid residues at the C-terminus of Hyb5 resulted in early cell lysis, even in the presence of Hyb515...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research