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Journal:MicroPubl Biol:000669
From Proteopedia
Gossypium hirsutum gene Gohir.A03G007700.1 encodes a potential VAN3-binding protein with a phosphoinositide-binding siteEmma R. Smith, Lauryn R. Caulley, Amanda M. Hulse-Kemp, Amanda R Storm, Angela K. Stoeckman [1] Molecular Tour The AlphaFold structure model for GhVAB-A0A1U8N485 predicted . The first region (colored in blue), from residues 111-224, consists primarily of four alpha helices and contains most of the DUF828 domain. The second region (in green) contains the PH domain residues 259-366 and consists of a single alpha helix and seven anti-parallel beta sheets. Although VAB proteins are only found in plants, the PH domain structure is found in proteins across kingdoms of life. PH domains often localize to membranes, contain a conserved set of secondary structures and commonly bind phosphatidylinositol phosphates involved in signaling pathways (Le Huray et al., 2022[4]). From published structures of other PH domains (Saccharomyces cerevisiae Avo1, PDB 3ulb and human protein kinase B/Akt, PDB 1h10), the core of the PH domain is shown to be a seven-stranded anti-parallel beta-sandwich closed at its C-terminus by an alpha-helix. At the N-terminus of this beta-sandwich are three variable loops containing positively charged residues forming a pocket of basic residues that bind negatively-charged phosphoinositides. When the , a deep binding pocket accommodating the phosphoinositide ligand was observed in the structure. Indeed, (Anionic (-) / Cationic (+)) and .  A structure-based alignment between GhVAB-A0A1U8N485 and human protein kinase B/Akt indicated that two of the five ligand-binding residues in B/Akt are completely conserved in GhVAB-A0A1U8N485, with two others being conservative substitutions (Thomas et al., 2002[5]). Evidence from sequence and structure features support that GhVAB-A0A1U8N485 is part of the VAN3-binding protein family. Furthermore, based on functional reports of other VAN3-binding proteins as well as structural analysis of our protein, GhVAB-A0A1U8N485 might be involved in regulating leaf size or vein development in cotton plants by binding phosphoinositides as part of an auxin signaling pathway. References
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