RESUMO
Tellurite exerts a deleterious effect on a number of small molecules containing sulfur moieties that have a recognized role in cellular oxidative stress. Because cysteine is involved in the biosynthesis of glutathione and other sulfur-containing compounds, we investigated the expression of Geobacillus stearothermophilus V cysteine-related genes cobA, cysK, and iscS and Escherichia coli cysteine regulon genes under conditions that included the addition of K2TeO3 to the culture medium. Results showed that cell tolerance to tellurite correlates with the expression level of the cysteine metabolic genes and that these genes are up-regulated when tellurite is present in the growth medium.
Assuntos
Antibacterianos/farmacologia , Bacillaceae/efeitos dos fármacos , Cisteína/genética , Escherichia coli/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Telúrio/farmacologia , Alquil e Aril Transferases/biossíntese , Bacillaceae/genética , Bacillaceae/fisiologia , Proteínas de Bactérias/biossíntese , Liases de Carbono-Enxofre/biossíntese , Cisteína/metabolismo , Cisteína Sintase/biossíntese , Escherichia coli/genética , Escherichia coli/fisiologia , Proteínas de Escherichia coli/biossíntese , RegulonRESUMO
Xanthomonas axonopodis pv. citri (Xac) SufE (XAC2355) is a member of a family of bacterial proteins that are conserved in several pathogens and phytopathogens. The Escherichia coli suf operon is involved in iron-sulfur cluster biosynthesis under iron-limitation and stress conditions. It has recently been demonstrated that SufE and SufS form a novel two-component cysteine desulfarase in which SufS catalyses the conversion of L-cysteine to L-alanine, forming a protein-bound persulfide intermediate. The S atom is then transferred to SufE, from which it is subsequently transferred to target molecules or reduced to sulfide in solution. Here, the cloning, expression, crystallization and phase determination of Xac SufE crystals are described. Recombinant SufE was crystallized in space group P2(1)2(1)2(1) and diffracted to 1.9 A resolution at a synchrotron source. The unit-cell parameters are a = 45.837, b = 58.507, c = 98.951 A, alpha = beta = gamma = 90 degrees. The calculated Matthews coefficient indicated the presence of two molecules in the asymmetric unit. Phasing was performed by molecular-replacement using E. coli SufE as a model (PDB code 1mzg) and an interpretable map was obtained.