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  • Transcriptome profiling of type VI secretion system core gene tssM mutant of Xanthomonas perforans highlights regulators controlling diverse functions ranging from virulence to metabolism
Title: Transcriptome profiling of type VI secretion system core gene tssM mutant of Xanthomonas perforans highlights regulators controlling diverse functions ranging from virulence to metabolism
ABSTRACT Type VI secretion system (T6SS) is a versatile, contact-dependent contractile nano-weapon in Gram-negative bacteria that fires proteinaceous effector molecules directly into prokaryotic and eukaryotic cells aiding in manipulation of the host and killing of competitors in complex niches. In plant pathogenic xanthomonads, T6SS has been demonstrated to play these diverse roles in individual pathosystems. However, the molecular network underlying the regulation of T6SS is still elusive inXanthomonasspp. To bridge this knowledge gap, we conducted anin vitrotranscriptome screen using plant apoplast mimicking minimal medium, XVM2 medium, to decipher the effect oftssMdeletion, a core gene belonging to T6SS-cluster i3*, on the regulation of gene expression inXanthomonas perforansstrain AL65. Transcriptomic data revealed that a total of 277 and 525 genes were upregulated, while 307 and 392 genes were downregulated in the mutant strain after 8 and 16 hours of growth in XVM2 medium. The transcript abundance of several genes associated with flagellum and pilus biogenesis as well as type III secretion system was downregulated in the mutant strain. Deletion oftssMof cluster-i3* resulted in upregulation of several T6SS genes belonging to cluster-i3*** and genes involved in biofilm and cell wall biogenesis. Similarly, transcription regulators likerpoN, Pho regulon,rpoE, andcsrAwere identified to be upregulated in the mutant strain. Our results suggest that T6SS modulates the expression of global regulators likecsrA,rpoN, andphoregulons, triggering a signaling cascade, and co-ordinates the expression of suite of virulence factors, stress response genes, and metabolic genes. IMPORTANCET6SS has received attention due to its significance in mediating interorganismal competition through contact-dependent release of effector molecules into prokaryotic and eukaryotic cells. Reverse-genetic studies have indicated the role of T6SS in virulence in a variety of plant pathogenic bacteria, including the one studied here,Xanthomonas. However, it is not clear whether such effect on virulence is merely due to a shift in the microbiome-mediated protection or if T6SS is involved in a complex virulence regulatory network. In this study, we conducted in vitro transcriptome profiling in minimal medium to decipher the signaling pathways regulated by tssM-i3* inX. perforansAL65. We show that TssM-i3* regulates the expression of a suite of genes associated with virulence and metabolism either directly or indirectly by altering the transcription of several regulators. These findings further expand our knowledge on the intricate molecular circuits regulated by T6SS in phytopathogenic bacteria.  more » « less
Award ID(s):
1942956
PAR ID:
10488369
Author(s) / Creator(s):
; ; ; ; ; ;
Editor(s):
Burbank, Lindsey Price
Publisher / Repository:
American Society for Microbiology
Date Published:
Journal Name:
Microbiology Spectrum
Volume:
12
Issue:
1
ISSN:
2165-0497
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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