Formin Leaky Cap Allows Elongation in the Presence of Tight Capping Proteins

Formins, characterized by formin homology domains FH1 and FH2, are required to assemble certain F-actin structures including actin cables, stress fibers, and the contractile ring. FH1FH2 in a recombinant fragment from a yeast formin (Bni1p) nucleates actin filaments in vitro [1, 2]. It also binds to...

Full description

Saved in:
Bibliographic Details
Published in:Current biology 2003-10, Vol.13 (20), p.1820-1823
Main Authors: Zigmond, Sally H., Evangelista, Marie, Boone, Charles, Yang, Changsong, Dar, Arvin C., Sicheri, Frank, Forkey, Joe, Pring, Martin
Format: Article
Language:English
Subjects:
Actin Cytoskeleton - metabolism
Chromatography
Chromatography, Gel
Dimerization
Microfilament Proteins - genetics
Microfilament Proteins - metabolism
Recombinant Fusion Proteins - metabolism
Saccharomyces cerevisiae Proteins - genetics
Saccharomyces cerevisiae Proteins - metabolism
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Formins, characterized by formin homology domains FH1 and FH2, are required to assemble certain F-actin structures including actin cables, stress fibers, and the contractile ring. FH1FH2 in a recombinant fragment from a yeast formin (Bni1p) nucleates actin filaments in vitro [1, 2]. It also binds to the filament barbed end where it appears to act as a “leaky” capper, slowing both polymerization and depolymerization by ∼50% [3]. We now find that FH1FH2 competes with tight capping proteins (including gelsolin and heterodimeric capping protein) for the barbed end. We also find that FH1FH2 forms a tetramer. The observation that this formin protects an end from capping but still allows elongation confirms that it is a leaky capper. This is significant because a nucleator that protects a new barbed end from tight cappers will increase the duration of elongation and thus the total amount of F-actin. The ability of FH1FH2 to dimerize probably allows the formin to walk processively with the barbed end as the filament elongates.
ISSN:0960-9822
1879-0445
DOI:10.1016/j.cub.2003.09.057