1xw7: Difference between revisions
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|PDB= 1xw7 |SIZE=350|CAPTION= <scene name='initialview01'>1xw7</scene>, resolution 2.30Å | |PDB= 1xw7 |SIZE=350|CAPTION= <scene name='initialview01'>1xw7</scene>, resolution 2.30Å | ||
|SITE= | |SITE= | ||
|LIGAND= <scene name='pdbligand= | |LIGAND= <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=IPH:PHENOL'>IPH</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene> | ||
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
|DOMAIN= | |||
|RELATEDENTRY=[[1ev3|1EV3]] | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1xw7 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1xw7 OCA], [http://www.ebi.ac.uk/pdbsum/1xw7 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1xw7 RCSB]</span> | |||
}} | }} | ||
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==Overview== | ==Overview== | ||
Naturally occurring mutations in insulin associated with diabetes mellitus identify critical determinants of its biological activity. Here, we describe the crystal structure of insulin Wakayama, a clinical variant in which a conserved valine in the A chain (residue A3) is substituted by leucine. The substitution occurs within a crevice adjoining the classical receptor-binding surface and impairs receptor binding by 500-fold, an unusually severe decrement among mutant insulins. To resolve whether such decreased activity is directly or indirectly mediated by the variant side chain, we have determined the crystal structure of Leu(A3)-insulin and investigated the photo-cross-linking properties of an A3 analogue containing p-azidophenylalanine. The structure, characterized in a novel crystal form as an R(6) zinc hexamer at 2.3 A resolution, is essentially identical to that of the wild-type R(6) hexamer. The variant side chain remains buried in a nativelike crevice with small adjustments in surrounding side chains. The corresponding photoactivatable analogue, although of low affinity, exhibits efficient cross-linking to the insulin receptor. The site of photo-cross-linking lies within a 14 kDa C-terminal domain of the alpha-subunit. This domain, unrelated in sequence to the major insulin-binding region in the N-terminal L1 beta-helix, is also contacted by photoactivatable probes at positions A8 and B25. Packing of Val(A3) at this interface may require a conformational change in the B chain to expose the A3-related crevice. The structure of insulin Wakayama thus evokes the reasoning of Sherlock Holmes in "the curious incident of the dog in the night": the apparent absence of structural perturbations (like the dog that did not bark) provides a critical clue to the function of a hidden receptor-binding surface. | Naturally occurring mutations in insulin associated with diabetes mellitus identify critical determinants of its biological activity. Here, we describe the crystal structure of insulin Wakayama, a clinical variant in which a conserved valine in the A chain (residue A3) is substituted by leucine. The substitution occurs within a crevice adjoining the classical receptor-binding surface and impairs receptor binding by 500-fold, an unusually severe decrement among mutant insulins. To resolve whether such decreased activity is directly or indirectly mediated by the variant side chain, we have determined the crystal structure of Leu(A3)-insulin and investigated the photo-cross-linking properties of an A3 analogue containing p-azidophenylalanine. The structure, characterized in a novel crystal form as an R(6) zinc hexamer at 2.3 A resolution, is essentially identical to that of the wild-type R(6) hexamer. The variant side chain remains buried in a nativelike crevice with small adjustments in surrounding side chains. The corresponding photoactivatable analogue, although of low affinity, exhibits efficient cross-linking to the insulin receptor. The site of photo-cross-linking lies within a 14 kDa C-terminal domain of the alpha-subunit. This domain, unrelated in sequence to the major insulin-binding region in the N-terminal L1 beta-helix, is also contacted by photoactivatable probes at positions A8 and B25. Packing of Val(A3) at this interface may require a conformational change in the B chain to expose the A3-related crevice. The structure of insulin Wakayama thus evokes the reasoning of Sherlock Holmes in "the curious incident of the dog in the night": the apparent absence of structural perturbations (like the dog that did not bark) provides a critical clue to the function of a hidden receptor-binding surface. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Weiss, M A.]] | [[Category: Weiss, M A.]] | ||
[[Category: Xu, B.]] | [[Category: Xu, B.]] | ||
[[Category: insulin receptor]] | [[Category: insulin receptor]] | ||
[[Category: leu-a30insulin]] | [[Category: leu-a30insulin]] | ||
[[Category: protein unfolding]] | [[Category: protein unfolding]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 00:55:29 2008'' | ||
