The role of histidine 200 in MndD, the Mn(II)-dependent 3,4-dihydroxyphenylacetate 2,3-dioxygenase from Arthrobacter globiformis CM-2, a site-directed mutagenesis study

The manganese-dependent 3,4-dihydroxyphenylacetate 2,3-dioxygenase (MndD) from Arthrobacter globiformis CM-2 is an extradiol-cleaving catechol dioxygenase that catalyzes aromatic ring cleavage of 3,4-dihydroxyphenylacetate (DHPA). Based on the recent crystal structure of the MndD-DHPA complex, a ser...

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Bibliographic Details
Published in:Journal of biological inorganic chemistry 2005-11, Vol.10 (7), p.751-760
Main Authors: Emerson, Joseph P, Wagner, Michelle L, Reynolds, Mark F, Que, Jr, Lawrence, Sadowsky, Michael J, Wackett, Lawrence P
Format: Article
Language:English
Subjects:
Arthrobacter - enzymology
Arthrobacter - genetics
Catechols - chemistry
Crystallography, X-Ray
Dioxygenases - chemistry
Dioxygenases - genetics
Electron Spin Resonance Spectroscopy
Histidine - chemistry
Hydrogen-Ion Concentration
Kinetics
Manganese - chemistry
Metals - chemistry
Models, Molecular
Mutagenesis, Site-Directed
Mutation
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Summary:The manganese-dependent 3,4-dihydroxyphenylacetate 2,3-dioxygenase (MndD) from Arthrobacter globiformis CM-2 is an extradiol-cleaving catechol dioxygenase that catalyzes aromatic ring cleavage of 3,4-dihydroxyphenylacetate (DHPA). Based on the recent crystal structure of the MndD-DHPA complex, a series of site-directed mutations were made at a conserved second-sphere residue, histidine 200, to gain insight into and clarify the role this residue plays in the Mn(II)-dependent catalytic mechanism. In this study, we report the activities and spectroscopic data of these H200 variants and their DHPA and 4-nitrocatechol (4-NC) complexes. The data collected from wild-type and mutant MndDs are consistent with a role for H200 interacting with a manganese-bound dioxygen moiety and are inconsistent with other previously proposed roles involving proton transfer. Spectroscopic observations, including unique low-field EPR signals found when DHPA and 4-NC are bound to the Mn(II) center of MndD, are discussed and their relationship to dioxygen activation catalyzed in MndD is explored.
ISSN:0949-8257
1432-1327
DOI:10.1007/s00775-005-0017-1