Soluble and particulate methane monooxygenase gene clusters of the type I methanotroph Methylovulum miyakonense HT12

The gene clusters encoding soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO) were cloned and sequenced from a new type I methanotroph, Methylovulum miyakonense HT12. The sMMO gene cluster consisted of the structural genes mmoXYBZDC, the regulatory genes mmoG and mmoR and another ORF orf1. Transcriptional analysis revealed that these sMMO genes were transcribed as a single unit from a Sigma 54-dependent promoter located upstream of mmoX. In the pMMO gene cluster, the pmoCAB operon was under the control of a Sigma 70-dependent promoter. The organization of each MMO operon was largely conserved with that of the previously described methanotrophs. However, unlike other methanotrophs, M. miyakonense HT12 harbored only a single copy of the pmoCAB gene. These data provide new insights into the structure of MMO genes.