AUTHOR=Tanui Collins Kipngetich , Shyntum Divine Yutefar , Sedibane Precious K. , Bellieny-Rabelo Daniel , Moleleki Lucy N. 

TITLE=Pectobacterium brasiliense 1692 Chemotactic Responses and the Role of Methyl-Accepting Chemotactic Proteins in Ecological Fitness

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.650894

DOI=10.3389/fpls.2021.650894

ISSN=1664-462X

ABSTRACT=<p>To adapt to changing environmental niches, bacteria require taxis, a movement toward or away from a stimulus (ligand). Chemotaxis has been studied in some members of the Soft Rot Pectobacteriaceae (SRP), particularly members of the genus <italic>Dickeya</italic>. On the contrary, there are fewer studies on this topic for the other genus in the SRP group, namely <italic>Pectobacterium</italic>. This study evaluated chemotactic responses in <italic>Pectobacterium brasiliense</italic> (<italic>Pb 1692</italic>) to various ligands. A total of 34 methyl-accepting chemotactic proteins (MCPs) were identified in the <italic>Pb 1692</italic> genome and the domain architectures of these MCPs were determined. Four <italic>Pb 1692</italic> MCPs previously shown to be differentially expressed during potato tuber infection were selected for further functional characterization. Toward this end, <italic>Pb 1692</italic> mutant strains each lacking either <italic>AED-0001492</italic>, <italic>AED-0003671</italic>, <italic>AED-0000304</italic>, or <italic>AED-0000744</italic> were generated. Two of these mutants (<italic>AED-0001492</italic> and <italic>AED-0003671</italic>), were attenuated in their ability to grow and respond to citrate and are thus referred to as <italic>MCP<sub><italic>cit2</italic></sub> and MCP<sub><italic>cit1</italic></sub></italic>, respectively, while the other two, <italic>AED-0000304</italic> (<italic>MCP</italic><sub><italic>xyl</italic></sub>) and <italic>AED-0000744</italic> (<italic>MCP</italic><sub><italic>asp</italic></sub>), were affected in their ability to respond to xylose and aspartate, respectively. Trans-complementation of the mutant strains restored swimming motility in the presence of respective ligands. The four MCP mutants were not affected in virulence but were significantly attenuated in their ability to attach to potato leaves suggesting that ecological fitness is an important contribution of these MCPs toward <italic>Pb 1692</italic> biology.</p>