M. Sugimoto et al., The first step in polyethylene glycol degradation by sphingomonads proceeds via a flavoprotein alcohol dehydrogenase containing flavin adenine dinucleotide, J BACT, 183(22), 2001, pp. 6694-6698
Several Sphingomonas spp. utilize polyethylene glycols (PEGs) as a sole car
bon and energy source, oxidative PEG degradation being initiated by a dye-l
inked dehydrogenase (PEG-DH) that oxidizes the terminal alcohol groups of t
he polymer chain. Purification and characterization of PEG-DH from Sphingom
onas terrae revealed that the enzyme is membrane bound. The gene encoding t
his enzyme (pegA) was cloned, sequenced, and expressed in Escherichia coli.
The purified recombinant enzyme was vulnerable to aggregation and inactiva
tion, but this could be prevented by addition of detergent. It is as a homo
dimeric protein with a subunit molecular mass of 58.8 kDa, each subunit con
taining 1 noncovalently bound flavin adenine dinucleotide but not Fe or Zu.
PEG-DH recognizes a broad variety of primary aliphatic and aromatic alcoho
ls as substrates. Comparison with known sequences revealed that PEG-DH belo
ngs to the group of glucose-methanol-choline (GMC) flavoprotein oxidoreduct
ases and that it is a novel type of flavoprotein alcohol dehydrogenase rela
ted (percent identical amino acids) to other, so far uncharacterized bacter
ial, membrane-bound, dye-linked dehydrogenases: alcohol dehydrogenase from
Pseudomonas oleovorans (46%); choline dehydrogenase from E. coli (40%); L-s
orbose dehydrogenase from Gluconobacter oxydans (38%); and 4-nitrobenzyl al
cohol dehydrogenase from a Pseudomonas species (35%).