PhyA, a secreted protein of Xanthomonas oryzae pv. oryzae, is required for optimum virulence and growth on phytic acid as a sole phosphate source

Chatterjee, Subhadeep ; Sankaranarayanan, Rajan ; Sonti, Ramesh V. (2003) PhyA, a secreted protein of Xanthomonas oryzae pv. oryzae, is required for optimum virulence and growth on phytic acid as a sole phosphate source Molecular Plant-Microbe Interactions, 16 (11). pp. 973-982. ISSN 0894-0282

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Official URL: http://apsjournals.apsnet.org/doi/pdf/10.1094/MPMI...

Related URL: http://dx.doi.org/10.1094/MPMI.2003.16.11.973

Abstract

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. We have identified a novel virulence deficient mutant (BXO1691) of X. oryzae pv. oryzae that has a Tn5 insertion in an open reading frame (phyA; putative phytase A) encoding a 373-amino acid (aa) protein containing a 28-aa predicted signal peptide. Extracellular protein profiles revealed that a 38-kDa band is absent in phyA mutants as compared with phyA+ strains. A BLAST search with phyA and its deduced polypeptide sequence indicated significant similarity with conserved hypothetical proteins in Xanthomonas axonopodis pv. citri and Xanthomonas campestris pv. campestris and limited homology to secreted phytases of Bacillus species. Homology modeling with a Bacillus phytase as the template suggests that the PhyA protein has a similar six-bladed beta-propeller architecture and exhibits conservation of certain critical active site residues. Phytases are enzymes that are involved in degradation of phytic acid (inositol hexaphosphate), a stored form of phosphate in plants. The phyA mutants exhibit a growth deficiency in media containing phytic acid as a sole phosphate source. Exogenous phosphate supplementation promotes migration of phyA X. oryzae pv. oryzae mutants in rice leaves. These results suggest that the virulence deficiency of phyA mutants is, at least in part, due to inability to use host phytic acid as a source of phosphate. phyA-like genes have not been previously reported to be involved in the virulence of any plant pathogenic bacterium.

Item Type:Article
Source:Copyright of this article belongs to The American Phytopathological Society.
ID Code:62624
Deposited On:22 Sep 2011 02:49
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