Structural features of PhoX, one of the phosphate-binding proteins from Pho regulon of Xanthomonas citri

16 p.-4 fig.-2 tab.In Escherichia coli, the ATP-Binding Cassette transporter for phosphate is encoded by the pstSCAB operon. PstS is the periplasmic component responsible for affinity and specificity of the system and has also been related to a regulatory role and chemotaxis during depletion of phosphate. Xanthomonas citri has two phosphate-binding proteins: PstS and PhoX, which are differentially expressed under phosphate limitation. In this work, we focused on PhoX characterization and comparison with PstS. The PhoX three-dimensional structure was solved in a closed conformation with a phosphate engulfed in the binding site pocket between two domains. Comparison between PhoX and PstS revealed that they originated from gene duplication, but despite their similarities they show significant differences in the region that interacts with the permeases.This work was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)” for Vanessa Pegos PhD fellowship and the Fundação de Amparo à Pesquisa do Estado de São Paulo—FAPESP” for the research grants 2011/20468-1 and 2013/09172-9.Peer reviewe