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PDBsum entry 2hml
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Oxidoreductase
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PDB id
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2hml
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References listed in PDB file
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Key reference
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Title
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Structural basis for regioselectivity and stereoselectivity of product formation by naphthalene 1,2-Dioxygenase.
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Authors
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D.J.Ferraro,
A.L.Okerlund,
J.C.Mowers,
S.Ramaswamy.
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Ref.
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J Bacteriol, 2006,
188,
6986-6994.
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PubMed id
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Abstract
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Rieske oxygenase (RO) systems are two- and three-component enzyme systems that
catalyze the formation of cis-dihydrodiols from aromatic substrates. Degradation
of pollutants in contaminated soil and generation of chiral synthons have been
the major foci of RO research. Substrate specificity and product regio- and
stereoselectivity have been shown to vary between individual ROs. While directed
evolution methods for altering RO function have been successful in the past,
rational engineering of these enzymes still poses a challenge due to the lack of
structural understanding. Here we examine the structural changes induced by
mutation of Phe-352 in naphthalene 1,2-dioxygenase from Pseudomonas sp. strain
NCIB 9816-4 (NDO-O(9816-4)). Structures of the Phe-352-Val mutant in native form
and in complex with phenanthrene and anthracene, along with those of wild-type
NDO-O(9816-4) in complex with phenanthrene, anthracene, and 3-nitrotoluene, are
presented. Phenanthrene was shown to bind in a different orientation in the
Phe-352-Val mutant active site from that in the wild type, while anthracene was
found to bind in similar positions in both enzymes. Two orientations of
3-nitrotoluene were observed, i.e., a productive and a nonproductive
orientation. These orientations help explain why NDO-O(9816-4) forms different
products from 3-nitrotoluene than those made from nitrobenzene dioxygenase.
Comparison of these structures among themselves and with other known ROs bound
to substrates reveals that the orientation of substrate binding at the active
site is the primary determinant of product regio- and stereoselectivity.
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