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Methylotrophic Bacillus methanolicus encodes two chromosomal and one plasmid born NAD+ dependent methanol dehydrogenase paralogs with different catalytic and biochemical properties

Methylotrophic Bacillus methanolicus encodes two chromosomal and one plasmid born NAD+ dependent methanol dehydrogenase paralogs with different catalytic and biochemical properties

Kategori
Vitenskapelig artikkel
Sammendrag
Bacillus methanolicus can utilize methanol as the sole carbon source for growth and it encodes an NAD+-dependent methanol dehydrogenase (Mdh), catalyzing the oxidation of methanol to formaldehyde. Recently, the genomes of the B. methanolicus strains MGA3 (ATCC53907) and PB1 (NCIMB13113) were sequenced and found to harbor three different putative Mdh encoding genes, each belonging to the type III Fe-NAD+-dependent alcohol dehydrogenases. In each strain, two of these genes are encoded on the chromosome and one on a plasmid; only one chromosomal act gene encoding the previously described activator protein ACT was found. The six Mdhs and the ACT proteins were produced recombinantly in Escherichia coli, purified, and characterized. All Mdhs required NAD+ as cosubstrate, were catalytically stimulated by ACT, exhibited a broad and different substrate specificity range and displayed both dehydrogenase and reductase activities. All Mdhs catalyzed the oxidation of methanol; however the catalytic activity for methanol was considerably lower than for most other alcohols tested, suggesting that these enzymes represent a novel class of alcohol dehydrogenases. The kinetic constants for the Mdhs were comparable when acting as pure enzymes, but together with ACT the differences were more pronounced. Quantitative PCR experiments revealed major differences with respect to transcriptional regulation of the paralogous genes. Taken together our data indicate that the repertoire of methanol oxidizing enzymes in thermotolerant bacilli is larger than expected with complex mechanisms involved in their regulation.
Språk
Engelsk
Forfatter(e)
Institusjon(er)
  • Norges teknisk-naturvitenskapelige universitet
  • SINTEF Industri / Bioteknologi og nanomedisin
  • Sveits
  • Tyskland
År
Publisert i
PLOS ONE
ISSN
1932-6203
Årgang
8
Hefte nr.
3