Primary Citation of Related Structures: 1IJJ, 1LCU
PubMed Abstract:
An antiparallel actin dimer has been proposed to be an intermediate species during actin filament nucleation. We now show that latrunculin A, a marine natural product that inhibits actin polymerization, arrests polylysine-induced nucleation at the level of an antiparallel dimer, resulting in its accumulation ...
An antiparallel actin dimer has been proposed to be an intermediate species during actin filament nucleation. We now show that latrunculin A, a marine natural product that inhibits actin polymerization, arrests polylysine-induced nucleation at the level of an antiparallel dimer, resulting in its accumulation. These dimers, when composed of pyrene-labeled actin subunits, give rise to a fluorescent excimer, permitting detection during polymerization in vitro. We report the crystallographic structure of the polylysine-actin-latrunculin A complex at 3.5-A resolution. The non-crystallographic contact is consistent with a dimeric structure and confirms the antiparallel orientation of its subunits. The crystallographic contacts reveal that the mobile DNase I binding loop of one subunit of a symmetry-related antiparallel actin dimer is partially stabilized in the interface between the two subunits of a second antiparallel dimer. These results provide a potential explanation for the paradoxical nucleation of actin filaments that have exclusively parallel subunits by a dimer containing antiparallel subunits.
Related Citations:
Actin-latrunculin A structure and function. Differential modulation of actin-binding protein function by latrunculin A Yarmola, E.G., Somasundaram, T., Boring, T.A., Spector, I., Bubb, M.R. (2000) J Biol Chem 275: 28120
Research Service, Malcom Randall Department of Veterans Affairs Medical Center and the University of Florida College of Medicine, Gainesville, Florida 32608, USA. bubbmr@medicine.ufl.edu
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