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Ronau JA, Paul LN, Fuchs JE, Corn IR, Wagner KT, Liedl KR, Abu-Omar MM, Das C. An additional substrate binding site in a bacterial phenylalanine hydroxylase. Eur Biophys J 2013; 42:691-708. [PMID: 23860686 PMCID: PMC3972754 DOI: 10.1007/s00249-013-0919-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 06/20/2013] [Accepted: 06/26/2013] [Indexed: 01/07/2023]
Abstract
Phenylalanine hydroxylase (PAH) is a non-heme iron enzyme that catalyzes oxidation of phenylalanine to tyrosine, a reaction that must be kept under tight regulatory control. Mammalian PAH has a regulatory domain in which binding of the substrate leads to allosteric activation of the enzyme. However, the existence of PAH regulation in evolutionarily distant organisms, for example some bacteria in which it occurs, has so far been underappreciated. In an attempt to crystallographically characterize substrate binding by PAH from Chromobacterium violaceum, a single-domain monomeric enzyme, electron density for phenylalanine was observed at a distal site 15.7 Å from the active site. Isothermal titration calorimetry (ITC) experiments revealed a dissociation constant of 24 ± 1.1 μM for phenylalanine. Under the same conditions, ITC revealed no detectable binding for alanine, tyrosine, or isoleucine, indicating the distal site may be selective for phenylalanine. Point mutations of amino acid residues in the distal site that contact phenylalanine (F258A, Y155A, T254A) led to impaired binding, consistent with the presence of distal site binding in solution. Although kinetic analysis revealed that the distal site mutants suffer discernible loss of their catalytic activity, X-ray crystallographic analysis of Y155A and F258A, the two mutants with the most noticeable decrease in activity, revealed no discernible change in the structure of their active sites, suggesting that the effect of distal binding may result from protein dynamics in solution.
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Affiliation(s)
- Judith A. Ronau
- Brown Laboratory of Chemistry, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN-47907, USA
| | - Lake N. Paul
- Bindley Biosciences Center, Purdue University, West Lafayette, IN 47907, USA
| | - Julian E. Fuchs
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, A-6020 Innsbruck, Austria
| | - Isaac R. Corn
- Brown Laboratory of Chemistry, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN-47907, USA
| | - Kyle T. Wagner
- Brown Laboratory of Chemistry, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN-47907, USA
| | - Klaus R. Liedl
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, A-6020 Innsbruck, Austria
| | - Mahdi M. Abu-Omar
- Brown Laboratory of Chemistry, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN-47907, USA
| | - Chittaranjan Das
- Brown Laboratory of Chemistry, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN-47907, USA,To whom correspondence should be addressed: Chittaranjan Das, Brown Laboratory of Chemistry, 560 Oval Drive, West Lafayette, IN, 47907, (765)-494-5478, Fax: (765)-494-0239,
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Corn IR, Astudillo-Sánchez PD, Zdilla MJ, Fanwick PE, Shaw MJ, Miller JT, Evans DH, Abu-Omar MM. Synthesis and Electrochemical Reactivity of Molybdenum Dicarbonyl Supported by a Redox-Active α-Diimine Ligand. Inorg Chem 2013; 52:5457-63. [PMID: 23578340 DOI: 10.1021/ic400348j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Isaac R. Corn
- Brown Laboratory, Department
of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Pablo D. Astudillo-Sánchez
- Brown Laboratory, Department
of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Michael J. Zdilla
- Brown Laboratory, Department
of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Phillip E. Fanwick
- Brown Laboratory, Department
of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Michael J. Shaw
- Department of Chemistry, Southern Illinois University at Edwardsville, Edwardsville, Illinois 62026, United States
| | - Jeffrey T. Miller
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Dennis H. Evans
- Brown Laboratory, Department
of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Mahdi M. Abu-Omar
- Brown Laboratory, Department
of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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