biostudies-literatureUnknown10Jiang XDeutsche ForschungsgemeinschaftType VI protein secretion systems (T6SSs) have been identified in many plant-associated bacteria. However, despite the fact that effector proteins may modulate host responses or interbacterial competition, only a few have been functionally dissected in detail. We dissected the T6SS in Azoarcus olearius strain BH72, a nitrogen-fixing model endophyte of grasses. The genome harbors two gene clusters encoding putative T6SSs, tss-1 and tss-2, of which only T6SS-2 shared genetic organization and functional homology with the H1-T6SS of Pseudomonas aeruginosa. While tss-2 genes were constitutively expressed, tss-1 genes were strongly up-regulated under conditions of nitrogen fixation. A comparative analysis of the wild type and mutants lacking either functional tss-1 or tss-2 allowed to differentiFrontiers in microbiology459https://www.ebi.ac.uk/biostudies/studies/S-EPMC6423157biostudies-literatureTwo Functionally Deviating Type 6 Secretion Systems Occur in the Nitrogen-Fixing Endophyte Azoarcus olearius BH72.PMC6423157Jiang XDinse THerglotz JSappa PKReinhold-Hurek BVolker UBeust AfalseTwo Functionally Deviating Type 6 Secretion Systems Occur in the Nitrogen-Fixing Endophyte Azoarcus olearius BH72.Type VI protein secretion systems (T6SSs) have been identified in many plant-associated bacteria. However, despite the fact that effector proteins may modulate host responses or interbacterial competition, only a few have been functionally dissected in detail. We dissected the T6SS in Azoarcus olearius strain BH72, a nitrogen-fixing model endophyte of grasses. The genome harbors two gene clusters encoding putative T6SSs, tss-1 and tss-2, of which only T6SS-2 shared genetic organization and functional homology with the H1-T6SS of Pseudomonas aeruginosa. While tss-2 genes were constitutively expressed, tss-1 genes were strongly up-regulated under conditions of nitrogen fixation. A comparative analysis of the wild type and mutants lacking either functional tss-1 or tss-2 allowed to differenti2019-01-01T00:00:00Z20192025-04-04T11:08:10.62Z2025-02-19T01:49:10.396ZS-EPMC64231573091505610.3389/fmicb.2019.00459