Regulation of the phosphate regulon in Escherichia coli K-12: regulation of the negative regulatory gene phoU and identification of the gene product.

AUTOR(ES)

Nakata, A

RESUMO

The phoU gene is one of the negative regulatory genes of the pho regulon of Escherichia coli. The DNA fragment carrying phoU has been cloned on pBR322 (Amemura et al., J. Bacteriol. 152:692-701, 1982). Further subcloning, Tn1000 insertion inactivation, and complementation tests localized the phoU gene within a 1.1-kilobase region on the cloned DNA fragment. The gene product of phoU was identified by the maxicell method as a protein with an approximate molecular weight of 27,000. A hybrid plasmid that contains a phoU'-lac'Z fused gene was constructed in vitro. This plasmid enabled us to study phoU gene expression by measuring the beta-galactosidase level in the cells. The plasmid was introduced into various regulatory mutants related to the pho regulon, and phoU gene expression in these strains was studied under limited and excess phosphate conditions. It was found that phoU is expressed at a higher level when the cells are cultured under the excess phosphate condition. The higher phoU expression was observed in a phoB mutant and a phoR-phoM double mutant. The implications of these findings for the regulation of pho genes are discussed.

Documentos Relacionados

• Purification of the phoU protein, a negative regulator of the pho regulon of Escherichia coli K-12.
• Repressor for the sn-glycerol-3-phosphate regulon of Escherichia coli K-12: cloning of the glpR gene and identification of its product.
• Identification of the phoM gene product and its regulation in Escherichia coli K-12.
• Role of PhoU in phosphate transport and alkaline phosphatase regulation.
• The recR locus of Escherichia coli K-12: molecular cloning, DNA sequencing and identification of the gene product.