PDBsum entry 1a90

Thiol protease inhibitor

PDB id: 1a90

Contents

Protein chain

108 a.a.

References listed in PDB file

Key reference

• Title: The structures of native phosphorylated chicken cystatin and of a recombinant unphosphorylated variant in solution.
• Authors: T.Dieckmann, L.Mitschang, M.Hofmann, J.Kos, V.Turk, E.A.Auerswald, R.Jaenicke, H.Oschkinat.
• Ref.: J Mol Biol, 1993, 234, 1048-1059.
• PubMed id: 8263912

Abstract

The solution structures of the phosphorylated form of native chicken cystatin and the recombinant variant AEF-S1M-M29I-M89L were determined by 2D, 3D and 4D-NMR. The structures turn out to be very similar, despite the substitutions and the phosphorylation of the wild-type. Their dominant feature is a five-stranded beta-sheet, which is wrapped around a five-turn alpha-helix, as shown by X-ray crystallographic studies of wild-type chicken cystatin. However, the NMR analysis shows that the second helix observed in the crystal is not present in solution. The phosphorylation occurs at S80, which is located in a flexible region. For this reason, very few effects on the structure are observed. Comparison of structures of the unphosphorylated variant and the wild-type shows small effects on H84 which is located in the supposed recognition site of the serine kinase. This recognition site appears to be well structured as a large loop-containing bulge of the beta-sheet. The N termini of both mutants, which contribute to a large extent to the binding to the proteinase, are very flexible. A loop structure involving the residues L7 to A10 as found in related inhibitors, such as in the kininogen domains 2 and 3, is not sufficiently populated to be observed.

Secondary reference #1

• Title: Conformational variability of chicken cystatin. Comparison of structures determined by X-Ray diffraction and nmr spectroscopy.
• Authors: R.A.Engh, T.Dieckmann, W.Bode, E.A.Auerswald, V.Turk, R.Huber, H.Oschkinat.
• Ref.: J Mol Biol, 1993, 234, 1060-1069.
• PubMed id: 8263913