Leprince, Audrey
[UCL]
Nuytten, Manon
[UCL]
July, Elise
[UCL]
Tesseur, Coralie
[UCL]
Mahillon, Jacques
[UCL]
Holins are small transmembrane proteins involved in the final stage of the lytic cycle of double-stranded DNA (dsDNA) phages. They cooperate with endolysins to achieve bacterial lysis, thereby releasing the phage progeny into the extracellular environment. Besides their role as membrane permeabilizers, allowing endolysin transfer and/or activation, holins also regulate the lysis timing. In this work, we provide functional characterization of the holins encoded by three phages targeting the Bacillus cereus group. The siphovirus Deep-Purple has a lysis cassette in which holP30 and holP33 encode two proteins displaying holin properties, including a transmembrane domain. The holin genes were expressed in Escherichia coli and induced bacterial lysis, with HolP30 being more toxic than HolP33. In Bacillus thuringiensis, the simultaneous expression of both holins was necessary to observe lysis, suggesting that they may interact to form functional pores. The myoviruses Deep-Blue and Vp4 both encode a single candidate holin (HolB and HolV, respectively) with two transmembrane domains, whose genes are not located near the endolysin genes. Their function as holin proteins was confirmed as their expression in E. coli impaired cell growth and viability. The HolV expression in B. thuringiensis also led to bacterial lysis, which was enhanced by coexpressing the holin with its cognate endolysin. Despite similar organizations and predicted topologies, truncated mutants of the HolB and HolV proteins showed different toxicity levels, suggesting that differences in amino acid composition influence their lysis properties.
Bibliographic reference |
Leprince, Audrey ; Nuytten, Manon ; July, Elise ; Tesseur, Coralie ; Mahillon, Jacques. Getting Outside the Cell: Versatile Holin Strategies Used by Distinct Phages to Leave Their Bacillus thuringiensis Host. In: Journal of Virology (Online), Vol. 96, no.14, p. 1-16 (2022) |
Permanent URL |
http://hdl.handle.net/2078.1/272700 |