Crystal Structure and Functional Assignment of Yfau, a Metal Ion Dependent Class II Aldolase from Escherichia Coli K12.Rea, D., Hovington, R., Rakus, J.F., Gerlt, J.A., Fulop, V., Bugg, T.D.H., Roper, D.I.
(2008) Biochemistry 47: 9955
- PubMed: 18754683
- DOI: 10.1021/bi800943g
- Primary Citation of Related Structures:
- PubMed Abstract:
One of the major challenges in the postgenomic era is the functional assignment of proteins using sequence- and structure-based predictive methods coupled with experimental validation. We have used these approaches to investigate the structure and fu ...
One of the major challenges in the postgenomic era is the functional assignment of proteins using sequence- and structure-based predictive methods coupled with experimental validation. We have used these approaches to investigate the structure and function of the Escherichia coli K-12 protein YfaU, annotated as a putative 4-hydroxy-2-ketoheptane-1,7-dioate aldolase (HpcH) in the sequence databases. HpcH is the final enzyme in the degradation pathway of the aromatic compound homoprotocatechuate. We have determined the crystal structure of apo-YfaU and the Mg (2+)-pyruvate product complex. Despite greater sequence and structural similarity to HpcH, genomic context suggests YfaU is instead a 2-keto-3-deoxy sugar aldolase like the homologous 2-dehydro-3-deoxygalactarate aldolase (DDGA). Enzyme kinetic measurements show activity with the probable physiological substrate 2-keto-3-deoxy- l-rhamnonate, supporting the functional assignment, as well as the structurally similar 2-keto-3-deoxy- l-mannonate and 2-keto-3-deoxy- l-lyxonate (see accompanying paper: Rakus, J. F., Fedorov, A. A., Fedorov, E. V., Glasner, M. E., Hubbard, B. K., Delli, J. D., Babbitt, P. C., Almo, S. C., and Gerlt, J. A. (2008) Biochemistry 47, 9944-9954). YfaU has similar activity toward the HpcH substrate 4-hydroxy-2-ketoheptane-1,7-dioate and synthetic substrates 4-hydroxy-2-ketopentanoic acid and 4-hydroxy-2-ketohexanoic acid. This indicates a relaxed substrate specificity that complicates the functional assignment of members of this enzyme superfamily. Crystal structures suggest these enzymes use an Asp-His intersubunit dyad to activate a metal-bound water or hydroxide for proton transfer during catalysis.
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry, UK.