X-ray crystallography and NMR studies of domain-swapped canecystatin-1

Napoleão F. Valadares, Rodrigo De Oliveira-Silva, Italo A. Cavini, Ivo De Almeida Marques, Humberto D'Muniz Pereira, Andrea Soares-Costa, Flavio Henrique-Silva, Hans R. Kalbitzer, Claudia E. Munte, Richard C. Garratt

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1028-1038
Number of pages11
JournalFEBS Journal
Issue number4
StatePublished - Feb 2013
Externally publishedYes


  • domain-swapped
  • NMR
  • phytocystatin
  • X-ray crystallography

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology


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