TY - JOUR
T1 - Polylysine induces an antiparallel actin dimer that nucleates filament assembly
T2 - Crystal structure at 3.5-Å resolution
AU - Bubb, Michael R.
AU - Govindasamy, Lakshmanan
AU - Yarmola, Elena G.
AU - Vorobiev, Sergey M.
AU - Almo, Steven C.
AU - Somasundaram, Thayumanasamy
AU - Chapman, Michael S.
AU - Agbandje-McKenna, Mavis
AU - McKenna, Robert
PY - 2002/6/7
Y1 - 2002/6/7
N2 - An antiparallel actin dimer has been proposed to be an intermediate species during actin filament nucleation. We now show that latrunculin A, Ba 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-Å 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.
AB - An antiparallel actin dimer has been proposed to be an intermediate species during actin filament nucleation. We now show that latrunculin A, Ba 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-Å 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.
UR - http://www.scopus.com/inward/record.url?scp=0037036364&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037036364&partnerID=8YFLogxK
U2 - 10.1074/jbc.M201371200
DO - 10.1074/jbc.M201371200
M3 - Article
C2 - 11932258
AN - SCOPUS:0037036364
SN - 0021-9258
VL - 277
SP - 20999
EP - 21006
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 23
ER -