Structural studies of the enzymes involved in the biosynthesis of the exopolysaccharide, xylellan gum, produced by xylella fastidiosa.

• Grant number: 01/07545-5
• Support Opportunities: Regular Research Grants
• Duration: October 01, 2001 - April 30, 2006
• Field of knowledge: Biological Sciences - Biochemistry
• Principal Investigator: Dulce Helena Ferreira de Souza
• Grantee: Dulce Helena Ferreira de Souza
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Citrus variegated chlorosis (CVC) is the disease "amarelinho" that affects orange trees, in Brazil, causing reduced leaf size and fruit that are small and early maturing. Xylella fastidiosa, the pathogenic agent of CVC, presents in its genome an operon containing 9 genes (B,C,D,E,F,H,J,K,M) responsible for the biosynthesis of the exopolysaccharide denoted xyleilan gum, that can be related to pathogenicity. Despite the synthesis of xyleilan gum is a complex process, the investigation of functionally of Gum operon and the structural studies of these enzymes will be an important tools for design of specific inhibitors and for further investigation of a possible disease contrai. In this work we propose clone, express, purify, crystallize and solve the structure three-dimensional of these enzymes. Seven genes (B,C,D,F,H,K,M) involved in xyleilan gum biosynthesis have been cloned in expression vectors. At the present three enzymes (gumC, gumD, gumH) were expressed in E. coli, in a soluble form, and are in final purification step. One of them (gumC), with a high purification degree, is been submitted at crystallization experiments. (AU)