The diguanylate cyclase GcpA inhibits the production of pectate lyases via the H-NS protein and RsmB regulatory RNA in Dickeya dadantii

5 years ago

The diguanylate cyclase GcpA inhibits the production of pectate lyases via the H-NS protein and RsmB regulatory RNA in Dickeya dadantii

Christopher M. Waters, Xiaochen Yuan, Chenyang He, Ching-Hong Yang, Quan Zeng, Geoffrey B. Severin, Fengquan Liu, Fang Tian

Dickeya dadantii 3937 secretes pectate lyases (Pels) to degrade the plant cell wall. Previously, we have demonstrated that EGcpB and EcpC function as cyclic-di-GMP (c-di-GMP) specific phosphodiesterases (PDEs) to positively regulate Pel production. However, the diguanylate cyclase (DGC) responsible for the synthesis of c-di-GMP and dichotomously regulation of Pel has remained a mystery. Here, we identified GcpA is the dominant DGC to negatively regulate Pel production by specifically repressing pelD gene expression. Quantitative real-time PCR (qRT-PCR) assays revealed that the expression levels of histone-like nucleoid-structuring protein encoding gene hns and the post-transcriptional regulator encoding genes rsmA and rsmB were significantly affected by GcpA. Deletion of hns or rsmB in the gcpAD418A site-directed mutant restored its Pel production and pelD expression, demonstrating that H-NS and RsmB contribute to GcpA-dependent regulation of Pel in D. dadantii. In addition, RsmB expression was subject to positive regulation by H-NS. Thus, we propose a novel pathway consisting of GcpA-H-NS-RsmB-RsmA-pelD that controls Pel production in D. dadantii. Furthermore, we showed that H-NS and RsmB are responsible for the GcpA-dependent regulation of motility and T3SS gene expression, respectively. Among the two PDEs involved in the regulation of Pels, only EGcpB regulates pelD expression through the same pathway as GcpA. This article is protected by copyright. All rights reserved.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1111/mpp.12665