[Functionality of Metdi5511gene in Methylobacterium dichloromethanicum DM4].

A knockout mutant of Methylobacterium dichloromethanicum DM4 with an inactivated gene of a putative transcription regulator METDI5511 (ΔMETDI5511) has been obtained. The expression of this gene increases many times when the strain is grown on dichloromethane compared to methanol. The mutant had a low growth rate on dichloromethane as compared with the original strain and was found to be more sensitive to influences of various types of stress (oxidative, osmotic stress, heat, and drying). The cells were stained with Fluorescent Brightener 28 (Calcofluor white), and the intensity of their fluorescence showed that the ΔMETDI5511 mutant had significantly increased numbers of surface polysaccharides with ß-1,3 and ß-1,4-glycoside bonds. The results indicate that the METDI5511 gene is involved in the regulation of surface polysaccharides that play an important role in adaptation of cells to growth on dichloromethane.

[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.