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 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 characterization of a SurE enzyme from a phytopathogen organism and, to our knowledge, the first solution structure of a SurE protein to be described.
Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas, Campinas São Paulo, Brazil.
Antonio M
AM
Saraiva
Marcelo A
MA
Reis
Susely F
SF
Tada
Luciana K
LK
Rosselli-Murai
Dilaine R S
DR
Schneider
Alexandre C
AC
Pelloso
Marcelo A S
MA
Toledo
Carlos
C
Giles
Ricardo
R
Aparicio
Anete P
AP
de Souza
D000494:Allosteric Regulation; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002850:Chromatography, Gel; D002942:Circular Dichroism; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D053838:Scattering, Small Angle; D014965:X-Rays; D044167:Xylella / Q000378:metabolism*
D001426:Bacterial Proteins