ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Phage Biology
This article is part of the Research TopicAdvancements in Symbiotic Phage Interactions with Microbial Hosts: Bacteria, Algae, and FungiView all 3 articles
Assessment of the phi6 lysis system using genetic complementation and heterologous expression in Escherichia coli and Pseudomonas syringae
Provisionally accepted
- Sandia National Laboratories, Albuquerque, United States
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
The RNA cystovirus phi6 represents a unique evolutionary outlier, encoding a holin and endolysin similar to tailed phages, yet lacking an identified gene for outer membrane disruption. In this study, we investigated the phi6 lysis system using genetic complementation experiments and heterologous expression in Escherichia coli and Pseudomonas syringae. Our results demonstrate that the phi6 endolysin is functional in both bacterial systems, while the phi6 holin does not show activity in either bacterial system when expressed using moderate expression systems. Combinations of lambda lysis gene controls performed as expected in Pseudomonas syringae. The phi6 holin requires overexpression or co-expression with other phi6 genes to exhibit lysis in E. coli. Overexpression of plasmids containing entire phi6 S-, M-, and L-segments cDNA in E. coli produced lysis profiles and cell morphology consistent with holin-endolysin expression, but outer membrane disruption was not observed. This suggests either phi6 has not evolved to carry an outer membrane disruptor or that the outer membrane disruptor is not active in our E. coli testbed. Our findings highlight the unusual nature of the phi6 lysis system.
Keywords: Cystoviridae, outer membrane disruptor, disruptin, spanin, holin, P10, P5
Received: 03 Oct 2025; Accepted: 21 Nov 2025.
Copyright: © 2025 Del Curto, Zamora, Lasley, Khan, Montalbano, Ricken and Cahill. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jesse Cahill, jcahill@sandia.gov
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.