MOLECULAR-CLONING OF A NOVEL GENE, DTSR, WHICH RESCUES THE DETERGENT SENSITIVITY OF A MUTANT DERIVED FROM BREVIBACTERIUM-LACTOFERMENTUM

Several strains of Corynebacterium and Brevibacterium are known for th eir ability to secrete large amounts of amino acids, especially L-glut amate, We focused on the mechanism of L-glutamate secretion triggered by a detergent, namely polyoxyethylenesorbitan monopalmitate (PESP). A mutant strain, AJ11060, derived from BI Brevibacterium lactofermentum ATCC 13869 indicates the sensitivity to PESP. A multicopy suppresser gene that compliments the sensitivity of AJ11060 to the detergent was derived from a gene library of B. lactofermentum AJ12036. A 2855-bp DN A fragment was cloned and sequenced, An open reading frame was found t hat coded for the rescuer gene of the sensitivity to PESP of AJ11060 a nd was designated dtsR. The expression of the dtsR gene in B. lactofer mentum was confirmed by using anti-DtsR antibody. The deduced DtsR pro tein indicated significant homology with some biotin enzymes such as t he beta chain of propionyl-CoA carboxylase from rat (48.3%) and human (48.7%), or a 12S chain of methylmalonyl-CoA carboxyltransferase from Propionibacterium freudenreichii (43.1%).