Serine transhydroxymethylase isoenzymes from a facultative methylotroph.

AUTOR(ES)

O'Connor, M L

RESUMO

Two serine transhydroxymethylase activities have been purified from a facultative methylotrophic bacterium. One enzyme predominates when the organism is grown on methane or methanol as the sole carbon and energy source, whereas the second enzyme is the major isoenzyme found when succinate is used as the sole carbon and energy source. The enzyme from methanol-grown cells is activated by glyoxylate, is not stimulated by Mg2+, Mn2+, or Zn2+, and has four subunits of 50,000 molecular weight each. The enzyme from succinate-grown cells is not activated by glyoxylate and is stimulated by Mg2+, Mn2+, and Zn2+, and sodium dodecyl sulfate-acrylamide gel electrophoresis indicates that this enzyme has subunit molecular weight of 100,000, the same as the molecular weight obtained for the active enzyme. Cells grown in the presence of both methanol and succinate incorporate less methanol carbon per unit time than cells grown on methanol and have a lower specific activity of the glyoxylate-activated enzyme than methanol-grown cells. Adenine, glyoxylate, or trimethoprim in the growth medium causes an increased level of serine transhydroxymethylase in both methanol- and succinate-grown cells by stimulating the synthesis of the glyoxylate-activated enzyme.

Documentos Relacionados

• Molecular cloning of a malyl coenzyme A lyase gene from Pseudomonas sp. strain AM1, a facultative methylotroph.
• Cloning, sequencing, expression, and regulation of the structural gene for the copper/topa quinone-containing methylamine oxidase from Arthrobacter strain P1, a gram-positive facultative methylotroph.
• Genetic manipulation of Bacillus methanolicus, a gram-positive, thermotolerant methylotroph.
• NADP-dependent glutamate dehydrogenase from a facultative methylotroph, Pseudomonas sp. strain AM1.
• Purification and characterization of hydroxypyruvate reductase from the facultative methylotroph Methylobacterium extorquens AM1.