Role of Two Methanol Dehydrogenases in Methanol Metabolism of Methylobacterium

In this study, the pyrroloquinoline quinone (PQQ) high-yield mutant J1-1 of Methylobacterium glucophilum MP688 was used to do bioinformatics analysis to extract the two methanol dehydrogenase (MDH) genes from the genome, mpq0771 and mpq2496. The effects of Ca²⁺ and La³⁺ on bacterial growth, PQQ synthesis, MDH expression, and enzyme activity were explored, as well as the roles of the two enzymes in methanol metabolism. The results showed that Ca²⁺ and La³⁺ both increased J1-1 bacteriophage growth and decreased PQQ synthesis in the context of fast viral development. In the presence of Ca²⁺, mpq0771 expression increased in strain J1-1. La³⁺ inhibited mpq0771 expression while promoting mpq2496 expression and increasing total bacterial MDH viability. The knockout bacteria J1-1Δmpq0771 could not grow in methanol, but with the addition of La³⁺, it could grow in methanol and synthesize PQQ, and MDH activity was identified. The product encoded by mpq0771 was a Ca²⁺-dependent MDH, and the product encoded by mpq2496 was a La³⁺-dependent MDH, and La³⁺ could increase the production of mpq2496 and replace mpq0771 as a methanol dehydrogenase.