Environmental Engineering Reference
In-Depth Information
N-terminal sequencing for the DmoB subunit. Further genes in close proximity to
dmoA
were predicted to encode enzymes involved in the synthesis of the flavin
cofactor as well as a sulfite oxidase and a further large subunit of a two subunit
FMN-dependent monooxygenase that had high similarity to alkanesulfonate
monooxygenase (SsuD) [
184
].
2.4.2 Distribution, Genomic Context, and Phylogeny of Dimethylsulfide
Monooxygenases
In terms of its evolutionary relationship, the large subunit of DMS monooxygenase
is a member of the luciferase superfamily. The most closely related homologues
of DmoA are the enzymes of the NtaA/SnaA/SoxA(DszA) monooxygenase
family which includes nitrilotriacetate monooxygenase (NtaA), pristinamycin
IIA synthase subunit A (SnaA), dibenzothiophene sulfone monooxygenase
(SoxA/DszA), and related enzymes [
184
].
Database searches with DmoA from
Hyphomicrobium sulfonivorans
identify a
large number of homologous sequences of predicted FMN-dependent oxidoreduc-
tases with varying annotation, including some annotated as DMS monooxygenase
large subunit genes. These originate from diverse bacteria including Proteobacteria
and Actinobacteria, but the function of these homologues has yet to be determined.
Potential homologues of DmoA with molecular masses of 53 kDa have been
observed as dimethylsulfone-induced polypeptides in strains of
Arthrobacter
methylotrophus
and
A. sulfonivorans
[
38
] and the presence of proteins with putative
molecular masses of 53 kDa and 19 kDa was observed in DMSO
2
-grown
Methylobacterium podarium
FM1 [
32
]. These proteins were absent when the
strains were grown on methylamine, suggesting that these strains may potentially
have similar DMS monooxygenases.
Phylogenetic analysis including representatives of characterized members of the
NtaA/SnaA/SoxA(DszA) monooxygenase family and related FMN-dependent oxi-
doreductases shows that DmoA of
H. sulfonivorans
is closely related to proteins
from
H. zavarzinii
and
Paracoccus
sp. TRP (Figure
9
). These further cluster with
DmoA homologues found in two
Pseudomonas
strains and a range of Actinobacteria
including strains of
Rothia
,
Kocuria
,
Arthrobacter
,
Leifsonia
,
Cryocola
,
Clavibacter
,
and
Pseudoclavibacter
. While not all strains of
Hyphomicrobium
and
Arthrobacter
may be able to degrade DMS, it is likely that the homologues found in these strains
represent
dmoA
genes.
The most closely related homologue of DmoA is found in
Hyphomicrobium
zavarzinii
, having an identity of 86 % at the amino acid level and a genomic
neighbourhood very similar to that seen around
dmoA
in
Hyphomicrobium
sulfonivorans
, encoding NADH-dependent flavin oxidoreductases,
FMN-dependent alkanesulfonate monooxygenases, sulfite oxidase, and enzymes
involved in flavin biosynthesis. In
Paracoccus
strains (J56, J4, TRP, J39, J55), the
Search WWH ::
Custom Search