Role of the FnIII domain associated with a cell wall‐degrading enzyme cellobiosidase of Xanthomonas oryzae pv. oryzae. (12th March 2022)

• Record Type: Journal Article
• Authors: Nathawat, Rajkanwar; Maku, Roshan V.; Patel, Hitendra K.; Sankaranarayanan, Rajan; Sonti, Ramesh V.
• Is Part Of: Molecular plant pathology. Volume 23:Number 7(2022)
• Page Start: 1011
• Page End: 1021
• Publication Date: 2022-03-12
• Subjects: exoglucanase -- FnIII domain -- rice -- secretion -- type II secretion system -- virulence -- Xanthomonas; Plant diseases -- Molecular aspects -- Periodicals; Plant-pathogen relationships -- Molecular aspects -- Periodicals; 571.936
• DOI: 10.1111/mpp.13205
• Languages: English
• ISSNs: 1464-6722

Abstract

Abstract: Cellobiosidase (CbsA) is an important secreted virulence factor of Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial blight of rice. CbsA is one of several cell wall‐degrading enzymes secreted by Xoo via the type II secretion system (T2SS). CbsA is considered a fundamental virulence factor for vascular pathogenesis. CbsA has an N‐terminal glycosyl hydrolase domain and a C‐terminal fibronectin type III (FnIII) domain. Interestingly, the secreted form of CbsA lacks the FnIII domain during in planta growth. Here we show that the presence of the FnIII domain inhibits the enzyme activity of CbsA on polysaccharide substrates like carboxymethylcellulose. The FnIII domain is required for the interaction of CbsA with SecB chaperone, and this interaction is crucial for the stability and efficient transport of CbsA across the inner membrane. Deletion of the FnIII domain reduced virulence similar to Δ cbsA Xoo, which corroborates the importance of the FnIII domain in CbsA. Our work elucidates a hitherto unknown function of the FnIII domain in enabling the virulence‐promoting activity of CbsA. Abstract : The fibronectin type III domain associated with the cellobiosidase enzyme of Xanthomonas oryzae pv. oryzae is required for efficient secretion of the protein and virulence on rice.