3UL5 image
Entry Detail
PDB ID:
3UL5
Title:
Saccharum officinarum canecystatin-1 in space group C2221
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2011-11-10
Release Date:
2012-11-28
Method Details:
Experimental Method:
Resolution:
2.30 Å
R-Value Free:
0.25
R-Value Work:
0.22
R-Value Observed:
0.22
Space Group:
C 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Canecystatin-1
Chain IDs:A, B, C, D
Chain Length:139
Number of Molecules:4
Biological Source:Saccharum officinarum
Primary Citation
X-ray crystallography and NMR studies of domain-swapped canecystatin-1.
Febs J. 280 1028 1038 (2013)
PMID: 23241243 DOI: 10.1111/febs.12095

Abstact

The three-dimensional structure of canecystatin-1, a potent inhibitor of cysteine proteases from sugarcane (Saccharum officinarum), has been solved in two different crystal forms. In both cases, it is seen to exist as a domain-swapped dimer, the first such observation for a cystatin of plant origin. Size exclusion chromatography and multidimensional NMR spectroscopy show the dimer to be the dominant species in solution, despite the presence of a measurable quantity of monomer undergoing slow exchange. The latter is believed to be the active species, whereas the domain-swapped dimer is presumably inactive, as its first inhibitory loop has been extended to form part of a long β-strand that forms a double-helical coiled coil with its partner from the other monomer. A similar structure is observed in human cystatin C, but the spatial disposition of the two lobes of the dimer is rather different. Dimerization is presumably a mechanism by which canecystatin-1 can be kept inactive within the plant, avoiding the inhibition of endogenous proteases. The structure described here provides a platform for the rational design of specific cysteine protease inhibitors for biotechnological applications.

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