African Journal of Parasitology Research

African Journal of Parasitology Research ISSN 2756-3391 Vol. 7 (10), pp. 001-009, October, 2020. © International Scholars Journals

Full Length Research Paper

A novel one-component system, XvgA involved in regulation of bacterial growth and virulence of Xanthomonas campestris pv. campestris

Daqing Mao^{1, 2}*^, Jun Tao^{3, 4}, Chunxia Li^{3, 5}, Chao Luo¹, Linlin Zheng¹ and Chaozu He^{3, 6}

¹School of Life Sciences, Tsinghua University, Beijing 100084, China.

²School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang, 110016, China.

³State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.

⁴CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.

⁵Graduate School of Chinese Academy of Sciences, Beijing 100039, China.

⁶Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Hainan University, Haikou, Hainan 570228, China.

Accepted 24 August, 2020

Abstract

One-component systems were the simplest and the most effective signaling mechanism in bacteria. Per-ARNT-Sim (PAS) domains were important modules that play crucial roles in light or oxygen or redox signaling in bacteria, and most characterized GGDEF proteins involved in cyclic di-GMP (c-di-GMP) synthesis played crucial roles in c-di-GMP signaling in bacteria. In Xanthomonas campestris pv. Campestris (Xcc), xvgA encoded a protein containing both a PAS and a GGDEF domains. Deletion of xvgA altered bacterial morphology and significantly reduced not only Xcc virulence but also bacterial growth, the growth assays under different light conditions indicated that XvgA involved in light (red or far-red) signaling in Xcc. XvgA had been shown to possess diguanylate cyclase (DGC) activity that converted GTP to c-di-GMP in vitro. Moreover, the PAS domain was necessary for its DGC activity, and glutamic acid 98 (E98) site in the PAS domain was an active site, which was verified with bioinformatics and biochemical assays in vitro. These findings indicated that XvgA was an important one-component system involved in c-di-GMP and light signaling, which contributed to regulate Xcc growth, motility and virulence.

Key words: Xcc, PAS domain, c-di-GMP, one-component system.