Microcystis aeruginosa msoT1/msoA1 locus displays features of a type I toxin–antitoxin system

Ruparčič, Matija (author), Dolinar, Marko (author)

Type I toxin–antitoxin (TA) systems consist of a protein toxin that exerts a cytostatic or cytotoxic effect and an antisense RNA antitoxin that prevents translation of the toxin. Although well studied, type I TA systems have so far only been discovered in bacteria from the phyla Proteobacteria, Firmicutes, and Tenericutes. We hypothesized that type I systems could also be present in Cyanobacteria. Through bioinformatic analysis of the Microcystis aeruginosa PCC 7806SL genome, we discovered ten putative type I TA loci and characterized six of them experimentally. Two of the six putative type I toxins, BH695_0320 and MsoT1 (BH695_4017), were observed to negatively affect Escherichia coli cell growth, with MsoT1 exerting a phenotype similar to SrnB, a known type I toxin. We focused on the MsoT1/MsoA1 TA system and confirmed the expression of MsoT1 and MsoA1 in our assay. Additionally, we found that MsoA1 delays the toxic effects of MsoT1, indicating its role as a cognate antitoxin of MsoT1. Our results suggest that MsoT1/MsoA1 represents a novel candidate type I TA system, the first to be discovered in the Cyanobacteria phylum.

• Language: English
• Keywords: type I toxin-antitoxin systems, cyanobacteria, Microcystis aeruginosa, bacterial toxins, novel toxin-antitoxin systems
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Publication date: 01.08.2025
• Year: 2025
• Number of pages: 25 str.
• Numbering: Vol. 17, iss. 8, art. 360
• PID: 20.500.12556/RUL-171107
• UDC: 577:582.232
• ISSN on article: 2072-6651
• DOI: 10.3390/toxins17080360
• COBISS.SI-ID: 243643907
• Publication date in RUL: 05.08.2025

Record is a part of a journal

• Title: Toxins : Elektronski vir
• Shortened title: Toxins
• Publisher: MDPI
• ISSN: 2072-6651
• COBISS.SI-ID: 517594649

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: sistemi toksin-antitoksin tipa I, cianobakterije, Microcystis aeruginosa, bakterijski toksini, novi sistemi toksin-antitoksin

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0048
• Name: Strukturna biologija