tailieunhanh - Báo cáo khóa học: Chaperone activity of cytosolic small heat shock proteins from wheat

Small Hsps (sHsps) and the structurally related eye lens a-crystallins are ubiquitous stress proteins that exhibit ATP-independent molecular chaperone activity. We studied the chaperone activity of dodecameric , a class I cytosolic sHsp from plants and the only eukaryotic sHsp for which a high resolution structure is available, along with the related wheat , which represents the evolutionarily distinct class II plant cytosolic sHsps. Despite the available structural information on , there is minimal data on its chaperone activity, and likewise, data on activity of the class II pro-teins is very limited. . | Eur. J. Biochem. 271 1426-1436 2004 FEBS 2004 doi Chaperone activity of cytosolic small heat shock proteins from wheat Eman Basha1 I Garrett J. Lee1 t Borries Demeler2 and Elizabeth Vierling1 1 Department of Biochemistry Molecular Biophysics University of Arizona Tucson AZ USA department of Biochemistry University of Texas San Antonio TX USA Small Hsps sHsps and the structurally related eye lens a-crystallins are ubiquitous stress proteins that exhibit ATP-independent molecular chaperone activity. We studied the chaperone activity of dodecameric wheat a class I cytosolic sHsp from plants and the only eukaryotic sHsp for which a high resolution structure is available along with the related wheat protein which represents the evolutionarily distinct class II plant cytosolic sHsps. Despite the available structural information on there is minimal data on its chaperone activity and likewise data on activity of the class II proteins is very limited. We prepared purified recombinant and and find that the class II protein comprises a smaller oligomer than the dodecameric suggesting class II proteins have a distinct mode of oligomer assembly as compared to the class I proteins. Using malate dehydrogenase as a substrate was shown to be a more effective chaperone than in preventing heat-induced malate dehydrogenase aggregation. As observed by EM morphology of sHsp substrate complexes depended on the sHsp used and on the ratio of sHsp to substrate. Surprisingly heat-denaturing firefly luciferase did not interact significantly with although it was fully protected by . In total the data indicate sHsps show substrate specificity and suggest that N-terminal residues contribute to substrate interactions. Keywords sHsps a-crystallins protein folding protein aggregation luciferase. Small Hsps sHsps and the structurally .