Novel Methylotrophy Genes of Methylobacterium extorquens AM1 Identified by using Transposon Mutagenesis Including a Putative Dihydromethanopterin Reductase

Abstract
Ten novel methylotrophy genes of the facultative methylotroph Methylobacterium extorquens AM1 were identified from a transposon mutagenesis screen. One of these genes encodes a product having identity with dihydrofolate reductase (DHFR). This mutant has a C 1 -defective and methanol-sensitive phenotype that has previously only been observed for strains defective in tetrahydromethanopterin (H 4 MPT)-dependent formaldehyde oxidation. These results suggest that this gene, dmrA , may encode dihydromethanopterin reductase, an activity analogous to that of DHFR that is required for the final step of H 4 MPT biosynthesis.