Gelsolin-Like Domain 3 Plays Vital Roles in Regulating the Activities of the Lily Villin/Gelsolin/Fragmin Superfamily

Abstract

The villin/gelsolin/fragmin superfamily is a major group of Ca2+-dependent actin-binding proteins (ABPs) involved in various cellular processes. Members of this superfamily typically possess three or six tandem gelsolin-like (G) domains, and each domain plays a distinct role in actin filament dynamics. Although the activities of most G domains have been characterized, the biochemical function of the G3 domain remains poorly understood. In this study, we carefully compared the detailed biochemical activities of ABP29 (a new member of this family that contains the G1-G2 domains of lily ABP135) and ABP135G1-G3 (which contains the G1-G3 domains of lily ABP135). In the presence of high Ca2+ levels in vitro (200 and 10 μM), ABP135G1-G3 exhibited greater actin severing and/or depolymerization and nucleating activities than ABP29, and these proteins had similar actin capping activities. However, in the presence of low levels of Ca2+ (41 nM), ABP135G1-G3 had a weaker capping activity than ABP29. In addition, ABP29 inhibited F-actin depolymerization, as shown by dilution-mediated depolymerization assay, differing from the typical superfamily proteins. In contrast, ABP135G1-G3 accelerated F-actin depolymerization. All of these results demonstrate that the G3 domain plays specific roles in regulating the activities of the lily villin/gelsolin/fragmin superfamily proteins.

Actin Cytoskeleton as Actor in Upstream and Downstream of Calcium Signaling in Plant Cells

“…Calcium signaling also regulates the dynamics of the actin cytoskeleton [12,18,19,49,50]. Pollen tube elongation depends on actin cytoskeleton remodeling, and actin dynamics are associated with the oscillation of the Ca 2+ concentration gradients at the tip region of the pollen tube [49,50,51,52,53,54,55,56], suggesting that the Ca 2+ gradient might precisely regulate actin dynamics to promote tube growth. In the tip-growing cell (e.g., protonema in the moss Physcomitrella patens ) high [Ca 2+ ] cyt promotes actin filament disassembly, but low [Ca 2+ ] cyt promotes the assembly of a tip-localized actin spot.…”

Mosquito-Borne Diseases and Omics: Tissue-Restricted Expression and Alternative Splicing Revealed by Transcriptome Profiling of Anopheles stephensi

“…3986.4 and ANSTF.3986.5 were significantly expressed only in midgut. Proteins encoded by this superfamily typically consist of three to six gelsolin-like domains, with each domain playing a critical role in actin filament remodeling (Qian et al, 2015;Sun et al, 1999). Vast variations observed in the differential expression of many forms of alternate transcripts for a large number of genes will lead to new discoveries in the molecular complexity involved in the complex biological traits such as vectorial capacity and host-vector-pathogen interaction.…”