| Literature References | 1. JANSSEN, D.B., PRIES, F. AND VAN DER PLOEG, J.R.
Genetics and biochemistry of dehalogenating enzymes.
ANNU.REV.MICROBIOL. 48 163-191 (1994).
2. KOONIN, E.V. AND TATUSOV, R.L.
Computer analysis of bacterial haloacid dehalogenases defines a large
superfamily of hydrolases with diverse specificity. Application of an
iterative approach to database search.
J.MOL.BIOL. 244(1) 125-132 (1994).
3. BEETHAM, J.K., GRANT, D., ARAND, M., GARBARINO, J., KIYOSUE, T.,
PINOT, F., OESCH, F., BELKNAP, W.R., SHINOZAKI, K. AND HAMMOCK, B.D.
Gene evolution of epoxide hydrolases and recommended nomenclature.
DNA CELL BIOL. 14(1) 61-71 (1995).
4. MYERS, R.W., WRAY, J.W., FISH, S. AND ABELES, R.H.
Purification and characterization of an enzyme involved in oxidative
carbon-carbon bond cleavage reactions in the methionine salvage pathway of
Klebsiella pneumoniae.
J.BIOL.CHEM. 268 24785-24791 (1993).
|
| Documentation | Microorganisms that can utilise halogenated compounds as growth substrates
produce enzymes that cleave carbon-halogen bonds and are commonly called
dehalogenases. The hydrolytic dehalogenases catalyse a nucleophilic
displacement reaction, with water as the sole co-substrate [1]. They are
divided into haloalkane dehalogenases and haloacid dehalogenases (HAD).
HADs belong to a large superfamily of hydrolases with diverse substrate
specificity, which also includes epoxide hydrolases, phosphoglycolate
phosphatases, histidinol phosphate phosphatases, nitrophenyl phosphatases
and numerous putative (not yet characterised) proteins [2].
The epoxide hydrolases (EH) add water to epoxides, forming the corresponding
diol. On the basis of sequence similarity, it has been proposed that the
mammalian soluble EHs contain 2 evolutionarily distinct domains [3]. The
N-terminal domain is similar to bacterial HADs; the C-terminal domain is
similar to soluble plant EH, microsomal EH, and bacterial haloalkane
dehalogenase.
HADHALOGNASE is a 7-element fingerprint that provides a signature for the
haloacid dehalogenase/epoxide hydrolase family. The fingerprint was derived
from an initial alignment of 10 sequences: the motifs were drawn from
conserved regions spanning virtually the full alignment length - motifs 1,
5 and 6 encode the putative catalytic triad, including the invariant Asp
Lys, and nucleophile (Ser or Asp) respectively, and overlap with motifs I,
II and III proposed in [2]. Two iterations on OWL26.0 were required to
reach convergence, at which point a true set comprising 12 sequences was
identified. Several partial matches were also found: a hypothetical protein
(YIHX_ECOLI) matches motifs 4-7; phosphoglycolate phosphatase (PGPC_ALCEU
and PGPP_ALCEU) matches motifs 4, 5 and 7; and hypothetical protein YigB
(YIGB_ECOLI and ECOXERC3) matches motifs 5, 6 and 7. Among the sequences
matching 2 motifs, only U00148 (Klebsiella oxytoca E1 enzyme), matching
motifs 1 and 6, has been characterised functionally [4].
An update on SPTR37_9f identified a true set of 12 sequences, and 13
partial matches.
|