Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2010-3-26
pubmed:abstractText
AlfA is a recently discovered DNA segregation protein from Bacillus subtilis that is distantly related to actin and the bacterial actin homologues ParM and MreB. Here we show that AlfA mostly forms helical 7/3 filaments, with a repeat of about 180 A, that are arranged in three-dimensional bundles. Other polymorphic structures in the form of two-dimensional rafts or paracrystalline nets were also observed. Here AlfA adopted a 16/7 helical symmetry, with a repeat of about 387 A. Thin polymers consisting of several intertwining filaments also formed. Observed helical symmetries of AlfA filaments differed from those of other members of the actin family: F-actin, ParM, or MreB. Both ATP and guanosine 5'-triphosphate are able to promote rapid AlfA filament formation with almost equal efficiencies. The helical structure is only preserved under physiological salt concentrations and at a pH between 6.4 and 7.4, the physiological range of the cytoplasm of B. subtilis. Polymerization kinetics are extremely rapid and compatible with a cooperative assembly mechanism requiring only two steps: monomer activation followed by elongation, making AlfA one of the most efficient polymerizing motors within the actin family. Phosphate release lags behind polymerization, and time-lapse total internal reflection fluorescence images of AlfA bundles are consistent with treadmilling rather than dynamic microtubule-like instability. High-pressure small angle X-ray scattering experiments reveal that the stability of AlfA filaments is intermediate between the stability of ParM and the stability of F-actin. These results emphasize that actin-like polymerizing machineries have diverged to produce a variety of filament geometries with diverse properties that are tailored for specific biological processes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
1089-8638
pubmed:author
pubmed:copyrightInfo
(c) 2010 Elsevier Ltd. All rights reserved.
pubmed:issnType
Electronic
pubmed:day
9
pubmed:volume
397
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1031-41
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
2010
pubmed:articleTitle
Polymeric structures and dynamic properties of the bacterial actin AlfA.
pubmed:affiliation
ERATO Actin Filament Dynamics Project, Japan Science and Technology Corporation, c/o RIKEN Harima Institute at Spring 8, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan. dpopp@imcb.a-star.edu.sg
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't