1dk5: Difference between revisions
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'''CRYSTAL STRUCTURE OF ANNEXIN 24(CA32) FROM CAPSICUM ANNUUM''' | '''CRYSTAL STRUCTURE OF ANNEXIN 24(CA32) FROM CAPSICUM ANNUUM''' | ||
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[[Category: Proust, J.]] | [[Category: Proust, J.]] | ||
[[Category: Schantz, R.]] | [[Category: Schantz, R.]] | ||
[[Category: | [[Category: Bell pepper]] | ||
[[Category: | [[Category: Calcium binding protein]] | ||
[[Category: | [[Category: Capsicum annuum]] | ||
[[Category: | [[Category: Plant annexin]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:56:31 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 13:56, 2 May 2008
CRYSTAL STRUCTURE OF ANNEXIN 24(CA32) FROM CAPSICUM ANNUUM
OverviewOverview
This work provides the first three-dimensional structure of a member of the plant annexin family and correlates these findings with biochemical properties of this protein. Annexin 24(Ca32) from Capsicum annuum was purified as a native protein from bell pepper and was also prepared by recombinant techniques. To overcome the problem of precipitation of the recombinant wild-type protein in crystallization trials, two mutants were designed. Whereas an N-terminal truncation mutant turned out to be an unstable protein, the N-terminal His-tagged annexin 24(Ca32) was crystallized, and the three-dimensional structure was determined by x-ray diffraction at 2. 8 A resolution. The structure refined to an R-factor of 0.216 adopts the typical annexin fold; the detailed structure, however, is different from non-plant annexins, especially in domains I and III and in the membrane binding loops on the convex side. Within the unit cell there are two molecules per asymmetric unit, which differ in conformation of the IAB-loop. Both conformers show Trp-35 on the surface. The loop-out conformation is stabilized by tight interactions of this tryptophan with residue side chains of a symmetry-related molecule and enforced by a bound sulfate. Characterization of this plant annexin using biophysical methods revealed calcium-dependent binding to phospholipid vesicles with preference for phosphatidylcholine over phosphatidylserine and magnesium-dependent phosphodiesterase activity in vitro as shown with adenosine triphosphate as the substrate. A comparative unfolding study of recombinant annexin 24(Ca32) wild type and of the His-tag fusion protein indicates higher stability of the latter. The effect of this N-terminal modification is also visible from CD spectra. Both proteins were subjected to a FURA-2-based calcium influx assay, which gave high influx rates for the wild-type but greatly reduced influx rates for the fusion protein. We therefore conclude that the N-terminal domain is indeed a major regulatory element modulating different annexin properties by allosteric mechanisms.
About this StructureAbout this Structure
1DK5 is a Single protein structure of sequence from Capsicum annuum. Full crystallographic information is available from OCA.
ReferenceReference
Annexin 24 from Capsicum annuum. X-ray structure and biochemical characterization., Hofmann A, Proust J, Dorowski A, Schantz R, Huber R, J Biol Chem. 2000 Mar 17;275(11):8072-82. PMID:10713128 Page seeded by OCA on Fri May 2 13:56:31 2008