Functional and structural characterization of YbbN protein of Xylella fastidiosa

Abstract

Xylella fastidiosa is a gram-negative bacteria and, a plant pathogen that causes Citrus Variegated Chlorosis (CVC) generating large losses for the agricultural sector. In the infection process, the plant uses several lines of defense against the pathogen. The generation of oxidizing species in the extracellular environment is a major defense mechanism used. However, the pathogens also have developed defense mechanisms to counteract or to minimize the damage caused by oxidative attacks of the plant. The defense system of the pathogen include antioxidant enzymes, like thioredoxin that is part of the thioredoxin (Trx) / thioredoxin reductase (Trr) system. In the Trx superfamily, the proteins has the typical Trx folding domain and the characteristic CxxC motif of disulfide reductase enzymes.YbbN is a 31 kDa protein, that possess a homologue Trx domain at its N-terminal portion (12 kDa) and a C-terminal region (20 kDa) containing 4 TPR motifs (tetratricopeptide repeat). The four TPR motifs forms two extra domains (TPR A and TPR B) with unknown functions. The E. coli YbbN has a SQHC motif, while the ORF XF2174, corresponding to YbbN in X. fastidiosa, has the typical CxxC motif of disulfide reductase, formed by CAPC. The main objectives of this project are the deep functional and structural characterization of X. fastidiosa YbbN (ORF XF2174). (AU)