5dfr
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(New page: 200px<br /><applet load="5dfr" size="450" color="white" frame="true" align="right" spinBox="true" caption="5dfr, resolution 2.3Å" /> '''CRYSTAL STRUCTURE OF ...)
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CRYSTAL STRUCTURE OF UNLIGANDED ESCHERICHIA COLI DIHYDROFOLATE REDUCTASE. LIGAND-INDUCED CONFORMATIONAL CHANGES AND COOPERATIVITY IN BINDING
Overview
The crystal structure of unliganded dihydrofolate reductase (DHFR) from, Escherichia coli has been solved and refined to an R factor of 19% at, 2.3-A resolution in a crystal form that is nonisomorphous with each of the, previously reported E. coli DHFR crystal structures [Bolin, J. T., Filman, D. J., Matthews, D. A., Hamlin, B. C., & Kraut, J. (1982) J. Biol. Chem., 257, 13650-13662; Bystroff, C., Oatley, S. J., & Kraut, J. (1990), Biochemistry 29, 3263-3277]. Significant conformational changes occur, between the apoenzyme and each of the complexes: the NADP+ holoenzyme, the, folate-NADP+ ternary complex, and the methotrexate (MTX) binary complex., The changes are small, with the largest about 3 A and most of them less, than 1 A. For simplicity a two-domain description is adopted in which one, domain contains the NADP+ 2'-phosphate binding site and the binding sites, for the rest of the coenzyme and for the substrate lie between the two, domains. Binding of either NADP+ or MTX induces a closing of the, PABG-binding cleft and realignment of alpha-helices C and F which bind the, pyrophosphate of the coenzyme. Formation of the ternary complex from the, holoenzyme does not involve further relative domain shifts but does, involve a shift of alpha-helix B and a floppy loop (the Met-20 loop) that, precedes alpha B. These observations suggest a mechanism for cooperativity, in binding between substrate and coenzyme wherein the greatest degree of, cooperativity is expressed in the transition-state complex. We explore the, idea that the MTX binary complex in some ways resembles the, transition-state complex.
About this Structure
5DFR is a Single protein structure of sequence from Escherichia coli with CL as ligand. Active as Dihydrofolate reductase, with EC number 1.5.1.3 Full crystallographic information is available from OCA.
Reference
Crystal structure of unliganded Escherichia coli dihydrofolate reductase. Ligand-induced conformational changes and cooperativity in binding., Bystroff C, Kraut J, Biochemistry. 1991 Feb 26;30(8):2227-39. PMID:1998681
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