AUTHOR=Kim Minyoung , Lee Jongchan , Heo Lynn , Han Sang-Wook 

TITLE=Putative Bifunctional Chorismate Mutase/Prephenate Dehydratase Contributes to the Virulence of Acidovorax citrulli

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.569552

DOI=10.3389/fpls.2020.569552

ISSN=1664-462X

ABSTRACT=<p><italic>Acidovorax citrulli</italic> (<italic>Ac</italic>) is a plant pathogenic bacterium that causes bacterial fruit blotch (BFB) in cucurbit crops. Despite its importance in the cucurbit industry, resistant cultivars/lines against BFB have not yet been identified. Therefore, there is a need to characterize the virulence factors/mechanisms in <italic>Ac</italic> to control the disease. Chorismate mutase, a key enzyme in the shikimate pathway, produces aromatic amino acids. Here, we report the functions of putative bifunctional <underline>c</underline>horismate <underline>m</underline>utase/<underline>p</underline>rephenate dehydratase in <italic><underline>Ac</underline></italic> (CmpAc) determined by proteomic analysis and phenotypic assays. <italic>Ac</italic> strain lacking CmpAc, <italic>AcΔcmpAc</italic>(EV), were significantly less virulent on watermelon in the germinated-seed inoculation and leaf infiltration assays. Sequence analysis revealed that CmpAc possesses two distinct domains: chorismate mutase and prephenate dehydratase, indicating that CmpAc is a bifunctional protein. Auxotrophic assays demonstrated that CmpAc is required for the biosynthesis of phenylalanine, but not tyrosine. The comparative proteomic analysis revealed that CmpAc is mostly involved in cell wall/membrane/envelop biogenesis. Furthermore, <italic>AcΔcmpAc</italic>(EV) showed reduced twitching halo production and enhanced biofilm formation. In addition, <italic>AcΔcmpAc</italic>(EV) was less tolerant to osmotic stress but more tolerant to antibiotics (polymyxin B). Thus, our study provides new insights into the functions of a putative bifunctional protein related to virulence in <italic>Ac</italic>.</p>