Positive selection for mutations affecting bioconversion of aromatic compounds in Agrobacterium tumefaciens: analysis of spontaneous mutations in the protocatechuate 3,4-dioxygenase gene.

ABSTRACT: A positive selection method for mutations affecting bioconversion of aromatic compounds was applied to a mutant strain of Agrobacterium tumefaciens A348. The nucleotide sequence of the A348 pcaHGB genes, which encode protocatechuate 3,4-dioxygenase (PcaHG) and beta-carboxy-cis,cis-muconate cycloisomerase (PcaB) for the first two steps in catabolism of the diphenolic protocatechuate, was determined. An omega element was introduced into the pcaB gene of A348, creating strain ADO2077. In the presence of phenolic compounds that can serve as carbon sources, growth of ADO2077 is inhibited due to accumulation of the tricarboxylate intermediate. The toxic effect, previously described for Acinetobacter sp., affords a powerful selection for suppressor mutations in genes required for upstream catabol

SUBMITTER: Parke D 

PROVIDER: S-EPMC94750 | biostudies-literature | 2000 Nov

REPOSITORIES: biostudies-literature