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Báo cáo khoa học: Functional and small-angle X-ray scattering studies of a new stationary phase survival protein E (SurE) from Xylella fastidiosa – evidence of allosteric behaviour

The genome data of bacteriumXylella fastidiosastrain 9a5c has identified severalorfsrelated to its phytopathogenic adaptation and survival. Among these genes, the surEcodifies a survival protein E (XfSurE) whose function is not so well understood, but functional assays in Escherichia colirevealed nucleotidase and exopolyphosphate activity. | Functional and small-angle X-ray scattering studies of a new stationary phase survival protein E SurE from Xylella fastidiosa - evidence of allosteric behaviour Antonio M. Saraiva1 Marcelo A. Reis2 3 Susely F. Tada1 Luciana K. Rosselli-Murai1 Dilaine R. S. Schneider1 Alexandre C. Pelloso1 Marcelo A. S. Toledo1 Carlos Giles3 Ricardo Aparicio2 and Anete P. de Souza1 1 Centro de Biologia Molecular e Engenharia Genetica CBMEG Universidade Estadualde Campinas Brazil 2 Instituto de Quimica Universidade Estadualde Campinas Brazil 3 Instituto de Fisica Gleb Wataghin Universidade Estadualde Campinas Brazil Keywords allosteric behaviour small-angle X-ray scattering stationary phase survival protein E SurE SurE oligomeric state Xylella fastidiosa Correspondence A. P. de Souza Centro de Biologia Molecular e Engenharia Genetica CBMEG Universidade Estadualde Campinas Campinas Sao Paulo Brazil Fax 55 19 3521 1089 Tel 55 19 3521 1132 E-mail anete@unicamp.br Received 5 June 2009 revised 11 August 2009 accepted 18 September 2009 doi 10.1111 j.1742-4658.2009.07390.x The genome data of bacterium Xylella fastidiosa strain 9a5c has identified several orfs related to its phytopathogenic adaptation and survival. Among these genes the surE codifies a survival protein E XfSurE whose function is not so well understood but functional assays in Escherichia coli revealed nucleotidase and exopolyphosphate activity. In the present study we report the XfSurE protein overexpression in E. coli and its purification. The overall secondary structure was analyzed by CD. Small-angle X-ray scattering and gel filtration techniques demonstrated that the oligomeric state of the protein in solution is a tetramer. In addition functional kinetics experiments were carried out with several monophosphate nucleoside substrates and revealed a highly positive cooperativity. An allosteric mechanism involving torsion movements in solution is proposed to explain the cooperative behaviour of XfSurE. This is the first .