Crystal structure of a bifunctional aldolase–dehydrogenase: Sequestering a reactive and volatile intermediate
- Departments of *Molecular, Cellular and Developmental Biology and †Chemistry and Biochemistry, Sinsheimer Laboratory, 1156 High Street, University of California, Santa Cruz, CA 95064; and §Department of Chemistry and Biochemistry, Concordia University, 1455 de Maisonneuve Boulevard West, Montreal, PQ, Canada H3G 1M8
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Edited by Gregory A. Petsko, Brandeis University, Waltham, MA, and approved April 15, 2003 (received for review November 7, 2002)
Abstract
The crystal structure of the bifunctional enzyme 4-hydroxy-2-ketovalerate aldolase (DmpG)/acylating acetaldehyde dehydrogenase (DmpF), which is involved in the bacterial degradation of toxic aromatic compounds, has been determined by multiwavelength anomalous dispersion (MAD) techniques and refined to 1.7-Å resolution. Structures of the two polypeptides represent a previously unrecognized subclass of metal-dependent aldolases, and of a CoA-dependent dehydrogenase. The structure reveals a mixed state of NAD+ binding to the DmpF protomer. Domain movements associated with cofactor binding in the DmpF protomer may be correlated with channeling and activity at the DmpG protomer. In the presence of NAD+ a 29-Å-long sequestered tunnel links the two active sites. Two barriers are visible along the tunnel and suggest control points for the movement of the reactive and volatile acetaldehyde intermediate between the two active sites.
Footnotes
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↵ ¶ To whom correspondence should be addressed. E-mail: vrielink{at}biology.ucsc.edu.
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↵ ‡ On leave of absence from: Department of Physics, Government Science College, Bangalore 560 012, India.
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This paper was submitted directly (Track II) to the PNAS office.
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Data deposition: The atomic coordinates and structure factors have been deposited in the Protein Data Bank, www.rcsb.org (PDB ID code 1NVM).
- Copyright © 2003, The National Academy of Sciences
