Genes involved in pyrimidine reductive catabolism (pyd) were isolated from a moderate thermophile, Brevibacillus agri NCHU 1002, and nine ORFs in an 8.2-kb DNA fragment were identified by DNA sequence analysis. The pyd gene cluster included three closely spaced ORFs, designated pydA, pydB, and pydC, transcribed in the same orientation. Based on their amino acid sequence identity and enzyme activity assay, the gene products were identified as dihydropyrimidine dehydrogenase (PydA), dihydropyrimidinase (PydB), and beta-alanine synthase (PydC). Northern blot and primer extension analyses revealed that the pydBC genes are induced by dihydrouracil and regulated under the control of sigma(54) recognized promoter at transcriptional level as a polycistronic operon. All results indicate that the pydABC genes participate in the pathway of the pyrimidine reductive catabolism. This is the first bacterial pyd gene cluster to be reported. (C) 2003 Elsevier Science (USA). All rights reserved.