Refined structure of villin 14T and a detailed comparison with other actin‐severing domains

Abstract

Villin 14T is the amino terminal actin monomer binding domain from the actin-severing and bundling protein villin. Its structure has been determined in solution using heteronuclear multidimensional nuclear magnetic resonance (NMR) spectroscopy (Markus MA, Nakayama T, Matsudaira P, Wagner G. 1994. Solution structure of villin 14T, a domain conserved among actin-severing proteins. Protein Science 3:70-81). An additional nuclear Overhauser effect (NOE) spectroscopy data set, acquired using improved gradient techniques, and further detailed analysis of existing data sets, produced an additional 601 NOE restraints for structure calculations. The overall fold does not change significantly with the additional NOE restraints but the definition of the structure is improved, as judged by smaller deviations among an ensemble of calculated structures that adequately satisfy the NMR restraints. Some of the side chains, especially those in the hydrophobic core of the domain, are much more defined. This improvement in the detail of the solution structure of villin 14T makes it interesting to compare the structure with the crystal structure of gelsolin segment 1, which shares 58% sequence identity with villin 14T, in an effort to gain insight into villin 14T's weaker affinity for actin monomers. Villin 14T has smaller side chains at several positions that make hydrophobic contacts with actin in the context of gelsolin segment 1. The structure is also compared with the structure of the related actin-severing domain, severin domain 2.

Discrete Molecular Dynamics: An Efficient And Versatile Simulation Method For Fine Protein Characterization

“…74 Core 1 is formed by predominantly aliphatic residues of the long helix (α2, amino acids (aa) 80–90), and core 2 is formed by short helix α3 (aa 103–110), β-strands β6 (aa 36–40) and β7 (aa 114–118) with a high fraction of aromatic residues 74 . We use the chicken villin 75 (PDB ID 2VIK) as the reference structure. In most of the trajectories, we observe rapid formation of the central β-sheet, and presence of many hydrophobic contacts of core 2 (Figure S11E).…”

An N-terminal, 830 residues intrinsically disordered region of the cytoskeleton-regulatory protein supervillin contains Myosin II- and F-actin-binding sites

“…All algorithms indicate that the N-terminal half of supervillin, which includes fragments M, A1, A2, and A3, is intrinsically disordered (Figure 3). Supervillin C-terminal sequences are highly homologous to regions responsible for generation of folding elements in the actin-binding proteins gelsolin and villin (Burtnick et al 1997; Markus, Matsudaira & Wagner 1997; Vardar, Buckley, Frank & McKnight 1999; Smirnov, Isern, Jiang, Hoyt & McKnight 2007). However, gelsolin/villin residues involved in binding to actin are replaced in supervillin by highly conserved alterations in surface loops and by the replacement of the actin filament-severing domain 1 in gelsolin and villin with the unique supervillin N-terminus (Smith et al 2010).…”

Villin controls the formation and enlargement of punctate actin foci in pollen tubes

“…Here, we have established a clear role for villin in the early actin-remodeling events involving severing activity in response to A23187. As the severing activity of villins is Ca 2+ responsive (Bao et al, 2012;Khurana et al, 2010;Kumar et al, 2004;Markus et al, 1997;Wu et al, 2015;Yokota et al, 2005;Zhang et al, 2010Zhang et al, , 2011 and A23187 is known to increase [Ca 2+ ] cyt (Diao et al, 2018;Franklin-Tong et al, 1996), this suggests that severing is an important early event triggered by increases in [Ca 2+ ] cyt , responsible for breaking down long actin filament bundles to generate more filament ends for monomer dissociation. We propose that villin activity is likely to act in concert or cooperatively with the Ca 2+ -responsive monomersequestering activity of profilin (Kovar et al, 2000a).…”

“…Interestingly, fimbrin, a side-binding ABP (McCurdy et al, 2001) did not colocalize to actin foci (Poulter et al, 2011). Villins are Ca 2+ -responsive ABPs (Kumar et al, 2004;Markus et al, 1997) that mediate actin alterations in pollen tubes in response to the elevation in [Ca 2+ ] cyt , but have not previously been studied in relation to the SI response in Papaver. Villin homologues were originally identified by biochemical means in plants (Yokota and Shimmen, 1999;Yokota et al, 2003) and the function and mechanism of action of villins have been documented extensively in Arabidopsis (Huang et al, 2015).…”