Location: Emerging Pests and Pathogens ResearchTitle: An AlgU-regulated antisense transcript encoded within the Pseudomonas syringae fleQ gene has a positive effect on motility
|MARKEL, ERIC - Former ARS Employee|
|WALL, HOLLIE - Cornell University - New York|
|MONTEIL, CAROLINE - Swansea University|
|VINATZER, BORIS - Virginia Tech|
Submitted to: Journal of Bacteriology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2018
Publication Date: 1/8/2018
Citation: Markel, E.J., Wall, H., Monteil, C., Vinatzer, B., Swingle, B.M. 2018. An AlgU-regulated antisense transcript encoded within the Pseudomonas syringae fleQ gene has a positive effect on motility. Journal of Bacteriology. https://doi.org/10.1128/JB.00576-17.
Interpretive Summary: Some plant pathogenic bacteria move using flagella, which are whip-like appendages on the surface of their cells. In this manuscript, we report our investigation of how the bacteria control expression or function of flagella. This is important because the ability to change whether these structures are expressed is part of the process of bacterial infection in plants and can determine whether the bacteria are able to infect the plant or not. We discovered a second gene hidden inside the major gene controlling flagella expression. This newly discovered second gene is controlled by cues that the bacteria detect when they are in plants. We eliminated the ability of the bacteria to produce the product of this gene and found that they move more than the wildtype, but that the genes that make the flagella are not changed. We also looked at other bacteria and found evidence that some of them also have a similar gene, and might also control motility in a similar way.
Technical Abstract: Bacterial flagella production is controlled by a multi-tiered regulatory system that coordinates expression of 40-50 subunits and correct assembly of these complicated structures. Flagellar expression is environmentally controlled, presumably to optimize the benefits and liabilities of flagellar expression with cell growth and survival. We recently reported a global survey of AlgU-dependent regulation and binding in Pseudomonas syringae pv. tomato DC3000 that included evidence for strong down-regulation of many flagellar and chemotaxis motility genes. Here, we returned to that data to look for other AlgU-dependent influences on the flagellar regulatory network. We identified an AlgU-dependent antisense transcript expressed from within the fleQ gene, which codes for the master regulator of flagellar biosynthesis in Pseudomonas. We tested the function of this antisense RNA and found that it counteracts AlgU-dependent down-regulation of motility. A phylogenetic analysis of the AlgU-dependent promoter controlling expression of the antisense transcript suggests that the capacity to produce the antisense transcript is a conserved feature in many pseudomonads and supports the hypothesis that maintenance of the promoter sequence and presumably the ability to produce the transcript is under positive selection in these bacteria.