Article ID Journal Published Year Pages File Type
1927473 Archives of Biochemistry and Biophysics 2006 8 Pages PDF
Abstract

We have found for the first time that a chromosomal gene, mlr6807, in Mesorhizobium loti encodes a new tetrameric pyridoxal 4-dehydrogenase (PLDH). The recombinant enzyme expressed in Escherichia coli cells was homogenously purified and characterized. The enzyme consisted of four subunits each with a molecular weight of 26,000 ± 1000, and exhibited Km and kcat values of 91 ± 2 μM and 149 ± 1 s−1, respectively. PLDH used NAD+ as a cosubstrate, showed no activity toward sugars, and belonged to a short-chain dehydrogenase/reductase family. The mlr6807 gene-disrupted M. loti cells could grow in a nutrient-rich TY medium but not in a synthetic one containing pyridoxine or pyridoxamine as the sole carbon and nitrogen source. Thus, it was found that PLDH is essential for the assimilation of vitamin B6 compounds and the second step enzyme in their degradation pathway in M. loti.

Related Topics
Life Sciences Biochemistry, Genetics and Molecular Biology Biochemistry
Authors
, , , , ,