Isolation and properties of a mutant of Escherichia coli with an insertional inactivation of the uspA gene, which encodes a universal stress protein.

AUTOR(ES)

Nyström, T

RESUMO

Cells of Escherichia coli increase greatly the synthesis of a small cytoplasmic protein as soon as the cell growth rate falls below the maximal growth rate supported by the medium, regardless of the condition inhibiting growth. The gene, designated uspA (universal stress protein A), encoding this protein has been cloned and mapped, and its nucleotide sequence has been determined (T. Nyström and F.C. Neidhardt, Mol. Microbiol. 6:3187-3198, 1992). We now report the isolation of an E. coli mutant defective in UspA synthesis because of insertional inactivation of the corresponding gene. Analysis of such a mutant demonstrated that it grows at a rate indistinguishable from that of the isogenic parent but lags significantly when diluted into fresh medium, regardless of the carbon source included. In addition, the mutant exhibits a diauxic type of growth when grown on certain single substrates, such as glucose and gluconate. This growth phenotype was found to be the result of abnormal metabolism of the carbon source (e.g., glucose) accompanied by excretion into the medium of acetate. The diauxic type of growth may be attributed to the failure of cells to form acetyl coenzyme A synthetase and to form isocitrate lyase and malate synthase of the glyoxalate bypass, needed for the assimilation of the produced acetate, until glucose or gluconate has been completely exhausted. The uspA mutant appears to dissimilate glucose at an elevated rate that is not commensurate with its biosynthetic processes. These results suggest that the role of protein UspA may be to modulate and reorganize the flow of carbon in the central metabolic pathways of E. coli during growth arrest.

Documentos Relacionados

• Effects of overproducing the universal stress protein, UspA, in Escherichia coli K-12.
• Isolation and analysis of the yeast TEA1 gene, which encodes a zinc cluster Ty enhancer-binding protein.
• A mutation in the ftsK gene of Escherichia coli affects cell-cell separation, stationary-phase survival, stress adaptation, and expression of the gene encoding the stress protein UspA.
• Cloning and insertional inactivation of the dye (sfrA) gene, mutation of which affects sex factor F expression and dye sensitivity of Escherichia coli K-12.
• Regulation of the adhE gene, which encodes ethanol dehydrogenase in Escherichia coli.