Metabolic Pathway of O-alkylhomoserine in Corynebacterium acetophilum

Abstract

The metabolic pathway of O-alkylhomoserine in Corynebacterium acetophilum was determined using mutants with defects in methionine biosynthesis and purified O-acetylhomoserine sulfhydrylase. The mutant strain M-74, defective in homoserine transacetylase, utilized O-alkylhomoserines and O-acetylhomoserine instead of methionine, but strain M-933, lacking cystathionine γ-synthase, did not. The incorporation of radioactive O-ethylhomoserine into cells was inhibited competitively by O-acetylhomoserine. Analysis of autoradiograms of two-dimensional thin-layer chromatograms showed that labeled O-ethylhomoserine was converted to O-acetylhomoserine by strain M-933 and finally metabolized to methionine by strain M-74. Furthermore, results showed that O-acetylhomoserine was synthesized from O-ethylhomoserine and acetic acid by a reversible side reaction of purified O-acetylhomoserine sulfhydrylase of C. acetophilum. These findings show that O-alkylhomoserine is converted to O-acetylhomoserine and then metabolized to methionine via cystathionine and homocysteine in cells of C. acetophilum starved of methionine. © 1979, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.