[Functionality of the xoxF Gene in Methylobacterium dichloromethanicum DM4]

Activation of expression of the xoxFgene encoding PQQ-dependent methanol/ethanol dehydrogenase (METDI2492) in dichloromethane- (DCM) -grown Methylobacterium dichloromethanicum DM4 was first demonstrated. The sequence of the only XoxF homolog found in the genome of strain DM4 exhibited 50% identity to that of the protein (MxaF) of the large subunit of methanol dehydrogenase (MDH). A knockout mutant with the inactivate xoxF gene (ΔxoxF) was found to be unable to grow on methanol due to the absence of the expression of the gene cluster of the classical MDH, as was confirmed by the GFP test. When grown of succinate, the ΔxoxF mutant exhibited a lower growth rate on DCM than the original strain and was more sensitive to various stress factors (oxidative, osmotic, and heat shock). Based on these data, the xoxF gene was hypothesized to belong to a group of genes affecting expression of the proteins of general stress response.