Plant 115-kDa Actin-Filament Bundling Protein, P-115-ABP, is a Homologue of Plant Villin and is Widely Distributed in Cells

Abstract

In many cases, actin filaments are arranged into bundles and serve as tracks for cytoplasmic streaming in plant cells. We have isolated an actin-filament bundling protein, which is composed of 115-kDa polypeptide (P-115-ABP), from the germinating pollen of lily, Lilium longiflorum [Nakayasu et al. (1998) BIOCHEM: Biophys. Res. Commun. 249: 61]. P-115-ABP shared similar antigenicity with a plant 135-kDa actin-filament bundling protein (P-135-ABP), a plant homologue of villin. A full-length cDNA clone (ABP115; accession no. AB097407) was isolated from an expression cDNA library of lily pollen by immuno-screening using antisera against P-115-ABP and P-135-ABP. The amino acid sequence of P-115-ABP deduced from this clone showed high homology with those of P-135-ABP and four villin isoforms of Arabidopsis thaliana (AtVLN1, AtVLN2, AtVLN3 and AtVLN4), especially AtVLN4, indicating that P-115-ABP can also be classified as a plant villin. The P-115-ABP isolated biochemically from the germinating lily pollen was able to arrange F-actin filaments with uniform polarity into bundles and this bundling activity was suppressed by Ca2+-calmodulin (CaM), similar to the actin-filament bundling properties of P-135-ABP. The P-115-ABP type of plant villin was widely distributed in plant cells, from algae to land plants. In root hair cells of Hydrocharis dubia, this type of plant villin was co-localized with actin-filament bundles in the transvacuolar strands and the sub-cortical regions. Microinjection of the antiserum against P-115-ABP into living root hair cells caused the disappearance of transvaculor strands and alteration of the route of cytoplasmic streaming. In internodal cells of Chara corallina in which the P-135-ABP type of plant villin is lacking, the P-115-ABP type showed co-localization with actin-filament cables anchored on the intracellular surface of chloroplasts. These results indicated that plant villins are widely distributed and involved in the organization of actin filaments into bundles throughout the plant kingdom.

Live cell imaging approaches reveal actin cytoskeleton-induced self-association of the actin-bundling protein WLIM1

“…So far, few studies have addressed the orientation of actin filaments within bundles and they have been limited to fixed tissues. Apart from pollen tubes and root hair cells, where unipolar bundles have been characterized by decoration with myosin S1 (Lenartowska and Michalska, 2008;Tominaga et al, 2000;Yokota and Shimmen, 1999;Yokota et al, 2003), the polarity of bundles remains largely unknown. With regard to these and our present data, we assume that the formation of unipolar bundles in vivo (e.g.…”

Actin bundling in plants

“…P-135-ABP and P-115-ABP, were isolated from lily (Lilium longiflorum) by biochemical fractionation [Nakayasu et al, 1998;Yokota et al, 1998] and subsequently recognized as being homologues of animal villins [Vidali et al, 1999;Yokota et al, 2003]. The two proteins were found to organize actin filaments into bundles with uniform polarity Yokota et al, 2003], and in both cases, this bundling activity was suppressed by Ca 21 /CaM .…”

“…P-135-ABP and P-115-ABP, were isolated from lily (Lilium longiflorum) by biochemical fractionation [Nakayasu et al, 1998;Yokota et al, 1998] and subsequently recognized as being homologues of animal villins [Vidali et al, 1999;Yokota et al, 2003]. The two proteins were found to organize actin filaments into bundles with uniform polarity Yokota et al, 2003], and in both cases, this bundling activity was suppressed by Ca 21 /CaM . Microinjection of antisera directed against the two lily proteins into living root hair cells causes the disappearance of transvacuolar strands and the alteration of the cytoplasmic streaming [Tominaga et al, 2000;Yokota et al, 2003].…”

“…The two proteins were found to organize actin filaments into bundles with uniform polarity Yokota et al, 2003], and in both cases, this bundling activity was suppressed by Ca 21 /CaM . Microinjection of antisera directed against the two lily proteins into living root hair cells causes the disappearance of transvacuolar strands and the alteration of the cytoplasmic streaming [Tominaga et al, 2000;Yokota et al, 2003]. Based on these observations it was proposed that P-115-ABP and P-135-ABP villins contribute to the AF arrangement in root hairs and pollen tubes Vidali et al, 1999].…”

Plant Actin-binding Protein SCAB1 Is Dimeric Actin Cross-linker with Atypical Pleckstrin Homology Domain

“…Several classes of actin bundlers have been characterized in plants, including villins (7)(8)(9)(10)(11)(12), fimbrins (13,14), certain formins (15,16), and LIM proteins (17)(18)(19). These actin bundlers are also present in most other eukaryotes.…”