tailieunhanh - Báo cáo khoa học: The crystal structure of annexin Gh1 from Gossypium hirsutum reveals an unusual S3 cluster Implications for cellulose synthase complex formation and oxidative stress response

The three-dimensional crystal structure of recombinant annexin Gh1 fromGossypium hirsutum(cotton fibre) has been determined and refined to the finalR-factor of at the resolution of A ˚ . This plant annexin consists of the typical annexin fold and is similar to the previously solved bell pepper annexinAnx24(Ca32), but significant differences are seen when compared to the structure of nonplant annexins. A comparison with the structure of the mamma-lian annexin AnxA5 indicates that canonical calcium bind-ing is geometrically possible within the membrane loops in domains I andIIofAnx(Gh1) in theirpresent conformation | Eur. J. Biochem. 270 2557-2564 2003 FEBS 2003 doi The crystal structure of annexin Gh1 from Gossypium hirsutum reveals an unusual S3 cluster Implications for cellulose synthase complex formation and oxidative stress response Andreas Hofmann1 Deborah P. Delmer2 and Alexander Wlodawer3 Institute of Cell Molecular Biology The University of Edinburgh Edinburgh Scotland 2The Rockefeller Foundation New York USA 3Macromolecular Crystallography Laboratory NCI at Frederick Frederick Maryland USA The three-dimensional crystal structure of recombinant annexin Gh1 from Gossypium hirsutum cotton fibre has been determined and refined to the final R-factor of at the resolution of A. This plant annexin consists of the typical annexin fold and is similar to the previously solved bell pepper annexin Anx24 Ca32 but significant differences are seen when compared to the structure of nonplant annexins. A comparison with the structure of the mammalian annexin AnxA5 indicates that canonical calcium binding is geometrically possible within the membrane loops in domains I and II of Anx Gh1 in their present conformation. All plant annexins possess a conserved tryptophan residue in the AB loop of the first domain this residue was found to adopt both a loop-in and a loop-out conformation in the bell pepper annexin Anx24 Ca32 . In Anx Gh1 the conserved tryptophan residue is in a surface-exposed position half way between both conformations observed in Anx24 Ca32 . The present structure reveals an unusual sulfur cluster formed by two cysteines and a methionine in domains II and III respectively. While both cysteines adopt the reduced thiolate forms and are separated by a distance of about A the sulfur atom of the methionine residue is in their close vicinity and apparently interacts with both cysteine sulfur atoms. While the cysteine residues are conserved in at least five plant annexins and in several mammalian members of the annexin family of .