Annexins: multifunctional components of growth and adaptation

Abstract

Plant annexins are ubiquitous, soluble proteins capable of Ca(2+)-dependent and Ca(2+)-independent binding to endomembranes and the plasma membrane. Some members of this multigene family are capable of binding to F-actin, hydrolysing ATP and GTP, acting as peroxidases or cation channels. These multifunctional proteins are distributed throughout the plant and throughout the life cycle. Their expression and intracellular localization are under developmental and environmental control. The in vitro properties of annexins and their known, dynamic distribution patterns suggest that they could be central regulators or effectors of plant growth and stress signalling. Potentially, they could operate in signalling pathways involving cytosolic free calcium and reactive oxygen species.

Annexins: Components of the Calcium and Reactive Oxygen Signaling Network

“…Unlike conventional channels, annexins are soluble phospholipidbinding proteins that can undergo conditional association with or insertion into membranes, directly from the soluble phase (Kourie and Wood, 2000;Gerke and Moss, 2002;Gorecka et al, 2007;Mortimer et al, 2008;Laohavisit and Davies, 2009). The presence of a hydrophilic pore at the center of the molecule is proposed to be the structural basis for annexin Ca 2+ channel activity (Gerke and Moss, 2002).…”

“…The presence of a hydrophilic pore at the center of the molecule is proposed to be the structural basis for annexin Ca 2+ channel activity (Gerke and Moss, 2002). Plant annexins (usually around 32-36 kD; Mortimer et al, 2008) now also appear capable of mediating passive, channel-like Ca 2+ transport (Hofmann et al, 2000;Mortimer et al, 2008;. Pepper (Capsicum annuum) annexin (CaANN24) mediates Ca 2+ influx into artificial vesicles (Hofmann et al, 2000).…”

“…This suggests that annexins could function in integrating ROS and Ca 2+ in stress signaling. Additionally, annexins are found at growth points such as root hair and pollen tube apices (for review, see Mortimer et al, 2008;Laohavisit and Davies, 2009) (Wymer et al, 1997). Additionally, ROS appear to promote the association of maize annexin with lipids .…”

Cloning, expression, and in silico analysis of a novel annexin gene FtANX1from Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.)

“…Annexin is one of the Ca 2+ -binding proteins responsible for a variety of cellular and physiological responses (Mortimer et al, 2008). Plant annexin was first described in 1989 as a Ca 2+ -dependent phospholipidbinding protein in higher plant cells (Boustead et al, 1989).…”

“…We modeled the 3D structure of FtANX1 using Capsicum annuum annexin (AnnCaP32) with the highest sequence identity (50.16%) as a template (Figure 2). The protein is dominated by four repeats and a type-II Ca 2+ -binding site (G-X-G-T-[38]-E) in repeat I, in which the W residue (position 27) may associate with phospholipid binding (Mortimer et al, 2008) (Figures 1 and 2). In addition, FtANX1 also contained a highly conserved H residue at amino acid 39 (Figure 1), which may play a role in stabilizing the structure through anchoring the N-terminal region to the C-terminal core (Konupka-Postupolska et al, 2011).…”