Phase variation of bacterial alkaline phosphatase

Connie Sue Schmellik-Sandage, Purdue University

Abstract

The pstS463 mutation, which was uncovered in a search for constitutive regulatory mutants of bacterial alkaline phosphatase (BAP) was found to cause BAP-phase variation. This phenotype is the alternation of enzyme synthesis between "on" and "off" states. This mutation is an IS2 insertion into the promoter of the pst operon which encodes the phosphate specific transport system. It reduces transcription through the operon. The pho regulatory genes are involved in regulating BAP-phase variation, as well as BAP expression in wild type cells. Mutations in phoB or phoR are epistatic to pstS463. Also diploidy for the phoBR region abolishes BAP-phase variation, producing BAP constitutive strains. Mutations in genes other than pho genes are also capable of abolishing BAP phase variation. Mutations in cya, crp and hupAB cause the pstS463 strains to exhibit a BAP repressed phenotype while mutations in himA or hip cause the pstS463 strains to exhibit a BAP constitutive phenotype. Possible mechanisms for these phenotypes are discussed.

Degree

Ph.D.

Advisors

Wanner, Purdue University.

Subject Area

Microbiology|Molecular biology|Genetics

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