The ribulose monophosphate pathway operon encoding formaldehyde fixation in a thermotolerant methylotroph, Bacillus brevis S1.

The hps and phi genes encoding 3-hexulose-6-phosphate synthase and 6-phospho-3-hexuloisomerase, the key enzymes of the ribulose monophosphate (RuMP) pathway for formaldehyde fixation, were cloned from the chromosomal DNA of a thermotolerant methylotroph, Bacillus brevis S1. Enzyme induction and Northern blot analyses revealed that both the hps and phi genes are induced by methanol or ethanol, and that their expression is controlled polycistronically at the transcription stage. Sequence analysis also suggested that the hps and phi genes constitute an RuMP operon. The gene organization of the RuMP operon and its surrounding region are unique among bacteria possessing the RuMP pathway genes.