期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：5
页码：1801-1806
DOI：10.1073/pnas.1317620111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Conformational changes of macromolecular complexes play key mechanistic roles in many biological processes, but large, highly flexible proteins and protein complexes usually cannot be analyzed by crystallography or NMR. Here, structures and conformational changes of the highly flexible, dynamic red cell spectrin and effects of a common mutation that disrupts red cell membranes were elucidated using chemical cross-linking coupled with mass spectrometry. Interconversion of spectrin between closed dimers, open dimers, and tetramers plays a key role in maintaining red cell shape and membrane integrity, and spectrins in other cell types serve these as well as more diverse functions. Using a minispectrin construct, experimentally verified structures of closed dimers and tetramers were determined by combining distance constraints from zero-length cross-links with molecular models and biophysical data. Subsequent biophysical and structural mass spectrometry characterization of a common hereditary elliptocytosis-related mutation of -spectrin, L207P, showed that cell membranes were destabilized by a shift of the dimer-tetramer equilibrium toward closed dimers. The structure of L207P mutant closed dimers provided previously unidentified mechanistic insight into how this mutation, which is located a large distance from the tetramerization site, destabilizes spectrin tetramers and cell membrane integrity.
关键词：hereditary hemolytic anemia ; protein conformations
