Primary Citation of Related Structures: 1RK2, 1RKA, 1RKS
PubMed Abstract:
The enzyme ribokinase phosphorylates ribose at O5* as the first step in its metabolism. The original X-ray structure of Escherichia coli ribokinase represented the ternary complex including ribose and ADP. Structures are presented here for the apo enzyme, as well as the ribose-bound state and four new ternary complex forms ...
The enzyme ribokinase phosphorylates ribose at O5* as the first step in its metabolism. The original X-ray structure of Escherichia coli ribokinase represented the ternary complex including ribose and ADP. Structures are presented here for the apo enzyme, as well as the ribose-bound state and four new ternary complex forms. Combined, the structures suggest that large and small conformational changes play critical roles in the function of this kinase. An initially open apo form can allow entry of the ribose substrate. After ribose binding, the active site lid is observed in a closed conformation, with the sugar trapped underneath. This closure and associated changes in the protein appear to assist ribokinase in recognition of the co-substrate ATP as the next step. Binding of the nucleotide brings about further, less dramatic adjustments in the enzyme structure. Additional small movements are almost certainly required during the phosphoryltransfer reaction. Evidence is presented that some types of movements of the lid are allowed in the ternary complex, which may be critical to the creation and breakdown of the transition state. Similar events are likely to take place during catalysis by other related carbohydrate kinases, including adenosine kinase.
Related Citations:
Structure of Escherichia Coli Ribokinase in Complex with Ribose and Nucleotide Determined to 1.8 A Resolution: Insights Into a New Family of Kinase Structures Sigrell, J.A., Cameron, A.D., Jones, T.A., Mowbray, S.L. (1998) Structure 6: 183
Purification, Characterization, and Crystallization of Escherichia Coli Ribokinase Sigrell, J.A., Cameron, A.D., Jones, T.A., Mowbray, S.L. (1997) Protein Sci 6: 2474
Ribokinase from Escherichia Coli K12. Nucleotide Sequence and Overexpression of the Rbsk Gene and Purification of Ribokinase Hope, J.N., Bell, A.W., Hermodson, M.A., Groarke, J.M. (1986) J Biol Chem 261: 7663
Organizational Affiliation:
Department of Molecular Biology, Uppsala University, Uppsala, Sweden.
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