Glycogen Phosphorylase b


1. Johnson L.N., Wilson K.S., Weber I.T., Wild D.L., Jenkins J.A., Stura E.A. (1978) Crystallographic Studies on the structure and function of glycogen phosphorylase b. Biochemical Society Transactions 6:1108-111.

2. Johnson L.N., Stura E.A., Wilson K.S., Sansom M.S.P., Weber I.T., (1979). Nucleotide binding to Glycogen Phosphorylase b in the crystal. Journal of Molecular Biology.134:639-653.

3. Johnson LN. Jenkins JA. Wilson KS. Stura EA. Zanotti G. (1980) Proposals for the catalytic mechanism of glycogen phosphorylase b prompted by crystallographic studies on glucose 1-phosphate binding. Journal of Molecular Biology. 140:565-580.

4. Jenkins JA. Johnson LN. Stuart DI. Stura EA. Wilson KS. Zanotti G. (1981) Phosphorylase: control and activity. [Review] Philosophical Transactions of the Royal Society of London - Series B: Biological Sciences. 293:23-41.

Abstract: Recent results from the crystallographic studies on glycogen phosphorylase b at 2 Å resolution are reviewed with special reference to other themes of the meeting. The structural similarity of the fold of 150 residues in phosphorylase to the observed in lactate dehydrogenase is discussed and the binding sites for NADH in phosphorylase are described. The binding of the potent inhibitor glucose-1,2-cyclic phosphate to phosphorylase b in the crystal has been studied at 3Å resolution. The results are compared with those previously obtained for glucose-1-phosphate and discussed with reference to proposals for a mechanism of catalysis that involves the essential cofactor pyridoxal phosphate.

5. Johnson L.N. Stura E.A. Sansom M.S.P. Babu Y.S. (1983) Oligosaccharide binding to glycogen phosphorylase b. Biochemical Society Transactions. 11, 142-144.

6. Stura E.A. Zanotti G. Babu Y.S. Sansom M.S. Stuart D.I. Wilson K.S. Johnson LN. Van de Werve G. (1983) Comparison of AMP and NADH binding to glycogen phosphorylase b. Journal of Molecular Biology. 170:529-565.

Abstract: The binding sites for the allosteric activator, AMP, to glycogen phosphorylase b are described in detail utilizing the more precise knowledge of the native structure obtained from crystallographic restrained least-squares refinement than has hitherto been available. Localized conformational changes are seen at the allosteric effector site that include shifts of between 1 and 2 Å for residues Tyr75 and Arg309 and very small shifts for the region of residues 42 to 44 from the symmetry-related subunit. Kinetic studies demonstrate that NADH inhibits the AMP activation of glycogen phosphorylase b. Crystallographic binding studies at 3.5 Å resolution show that NADH binds to the same sites on the enzyme as AMP, i.e. the allosteric effector site N, which is close to the subunit-subunit interface, and the nucleoside inhibitor site I, which is some 12 Å from the catalytic site. The conformations of NADH at the two sites are different but both conformations are ``folded'' so that the nicotinamide ring is close (approx. 6 Å) to the adenine ring. These conformations are compared with those suggested from solution studies and with the extended conformations observed in the single crystal structure of NAD+ and for NAD bound to dehydrogenases. Possible mechanisms for NADH inhibition of phosphorylase activation are discussed.

7. Wilson K.S., Stura E.A., Wild D.L., Todd R.J., Stuart D.I., Babu Y.S., Jenkins J.A., Standing T.S., and Johnson L.N., Fourme R., Kahn R., et al. (1983). Macromolecular Crystallography with synchrotron radiation. J. Appl. Cryst. 16:28-41.

8. Sansom M.S. Babu Y.S. Hajdu J. Stuart D.I. Stura E.A. Johnson L.N. (1984) The role of pyridoxal phosphate in glycogen phosphorylase b; structure, environment and relationship to catalytic mechanism. Progress in Clinical & Biological Research. 144A, 127-146.

9. Lorek A. Wilson K.S. Sansom M.S. Stuart D.I. Stura E.A. Jenkins J.A. Zanotti G. Hajdu J. Johnson L.N. (1984) Allosteric interactions of glycogen phosphorylase b. A crystallographic study of glucose 6-phosphate and inorganic phosphate binding to di-imidate-cross-linked phosphorylase b. Biochemical Journal. 218:45-60.

Abstract: The binding to glycogen phosphorylase b of glucose 6-phosphate and inorganic phosphate (respectively allosteric inhibitor and substrate/activator of the enzyme) were studied in the crystal at 0.3 nm (3Å) resolution. Glucose 6-phosphate binds in the a-configuration at a site that is close to the AMP allosteric effector site at the subunit-subunit interface and promotes several conformational changes. The phosphate-binding site of the enzyme for glucose 6-phosphate involves contacts to two cationic residues, Arg-309 and Lys-247. This site is also occupied in the inorganic-phosphate-binding studies and is therefore identified as a high-affinity phosphate-binding site. It is distinct from the weaker phosphate-binding site of the enzyme for AMP, which is 0.27 nm(2.7Å) away. The glucose moiety of glucose 6-phosphate and the adenosine moiety of AMP do not overlap. The results provide a structural explanation for the kinetic observations that glucose 6-phosphate inhibition of AMP activation of phosphorylase b is partially competitive and highly co-operative. The results suggest that the transmission of allosteric conformational changes involves an increase in affinity at phosphate-binding sites and relative movements of a-helices. In order to study glucose 6-phosphate and phosphate binding it was necessary to cross-link the crystals. The use of dimethyl malonic-imidate as a new cross-linking reagent in protein crystallography is discussed.