A BACILLUS-SUBTILIS LOCUS ENCODING SEVERAL GENE-PRODUCTS AFFECTING TRANSPORT OF CATIONS

A 3.6-kb DNA fragment from Bacillus subtilis was found to complement t he K+ uptake-deficient Escherichia coli strain TK2420. Transformation with a pKLO61 plasmid harboring this fragment conferred the capacity t o grow on a minimal medium containing only 10 mM K+. Insertional mutag enesis and subcloning identified a single gene responsible for the com plementation. This gene coded for an apparent homolog of E. coli TrkA. Sequence analysis of the cloned region also revealed three additional open reading frames. These included: a gene encoding a homolog to the czcD gene product of Alcaligenes eutrophus, a lysR-type regulatory ge ne which was found to enhance Na+ resistance in E. coli NM81 (Delta nh aA) in a separate complementation test, and an orfD with no significan t similarity to sequences deposited in Genbank.