The cysteine 354 and 277 residues of Salmonella enterica serovar Typhi EnvZ are determinants of autophosphorylation and OmpR phosphorylation.
An initial biochemical characterization of the Salmonella enterica serovar Typhi (S. Typhi) EnvZ sensor protein and several mutant derivatives was performed. Autophosphorylation levels were higher for Escherichia coli EnvZ, intermediate for S. enterica serovar Typhimurium EnvZ and very low for S. Typhi EnvZ, in spite of their high amino acid sequence identity. Consequently, OmpR phosphorylation was related to EnvZ autophosphorylation. Among the mutant derivatives, a C354G mutation in S. Typhi EnvZ resulted in a substantial increase in autophosphorylation, while mutation of its other cysteine residue at position 277 to L or S decreased the EnvZ autophosphorylation level. Upon heterodimerization, the S. Typhi C354G mutant complemented the wild type in vitro, increasing the EnvZ-P yield of both monomers, in accordance with the model where EnvZ autophosphorylation occurs in trans, indicating that dimer formation is a dynamic process. Hence, the C354 and the C277 residues are fundamental in determining the particular intrinsic biochemical characteristics of EnvZ.
Oropeza
Ricardo
R
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico. oropeza@ibt.unam.mx
Calva
Edmundo
E
D019943:Amino Acid Substitution / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology; D005816:Genetic Complementation Test; D000071677:Histidine Kinase; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012485:Salmonella typhi / Q000235:genetics / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000201:enzymology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D001425:Bacterial Outer Membrane Proteins; D010750:Phosphoproteins; D014157:Transcription Factors; D011494:Protein Kinases; D000071677:Histidine Kinase