Characterization of 2,5-dihydroxypyridine dioxygenases from Sinorhizobium sp. L1

Abstract

The Sinorhizobium  sp. L1 bacteria utilize 3-hydroxypyridine and nicotinic acid by different pathways. The biosynthesis of the 2,5-dihydroxypyridine 5,6-dioxygenase in Sinorhizobium  sp. L1 is induced by 3-hydroxypyridine as well as nicotinic acid, however, the distinct isoforms of the enzyme are produced depending on the applied inducer. Both isoforms of the enzyme have been purified and characterized. A 10.4  kb DNA fragment has been cloned from Sinorhizobium  sp. L1 by using data of the de  novo sequencing of the purified enzymes. According to the nucleotide sequence analysis, the cloned fragment encodes a part of the degradation pathway of nicotinic acid. The orf9 gene has been cloned and expressed in Escherichia coli cells. The cells produce an active 2,5-dihydroxypyridine 5,6-dioxygenase.