Two components of the rhpPC operon coordinately regulate the type III secretion system and bacterial fitness in Pseudomonas savastanoi pv. phaseolicola

• DOI: 10.1371/journal.ppat.1007673
• Publication Date: 2019-04-18T17:47:12Z
• Authors: Kun Li; Yanan Zhu; Wei Yan; Xin Deng; Yanmei Xiao; Liyang Song; Rongxiang Fang; Yantao Jia; Xiaoyan Tang
• Keywords: Xanthomonas

Many plant bacterial pathogens including Pseudomonas species, utilize the type III secretion system (T3SS) to deliver effector proteins into cells. Genes encoding T3SS and its effectors are repressed in nutrient-rich media but rapidly induced after bacteria enter a or transferred nutrient-deficient media. To understand how genes regulated, we screened for P. savastanoi pv. phaseolicola (Psph) mutants displaying diminished induction of avrPto-luc, reporter genes, Arabidopsis. A mutant carrying transposon insertion gene coding small functional unknown protein, designated as rhpC, was identified that poorly avrPto-luc plants minimal medium (MM). Interestingly, rhpC is located immediately downstream putative metalloprotease named rhpP, two organized an operon rhpPC; rhpP displayed different RNA expression patterns King’s B (KB) MM. Deletion whole rhpPC locus did not significantly affect induction, implying coordinated actions regulating genes. Further analysis showed RhpC cytoplasmic protein interacted with RhpP targeted periplasm. In absence RhpC, localized cytoplasm caused reduction HrpL, key regulator also reduced fitness Psph. Expression alone E. coli inhibited growth. The detrimental effect on Psph required active sites, when co-expressed RhpP. coordination between tuning cell reveals novel regulatory mechanism pathogenesis. function periplasm remains be studied.