Journal:MicroPubl Biol:000669
From Proteopedia
Gossypium hirsutum gene Gohir.A03G007700.1 encodes a potential VAN3-binding protein with a phosphoinositide-binding siteAmanda R Storm, Amanda M. Hulse-Kemp [1] Molecular Tour The AlphaFold structure model for GhVAB-A0A1U8N485 predicted two distinct folding regions with high confidence from Gly111-Arg224 and Gln259-Val366. The first region, from residues 111-224, consists primarily of four alpha helices and contains most of the DUF828 domain. The second region 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). 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 PH domain of human protein kinase B/Akt containing a bound phosphatidylinositol trisphosphate ligand (PDB 1H10) was overlaid with the GhVAB-A0A1U8N485 PH domain, a deep binding pocket accommodating the phosphoinositide ligand was observed in the structure. Indeed, this GhVAB-A0A1U8N485 binding pocket is lined with positively-charged amino acids that could interact with the negatively-charge phosphate groups and residues within this pocket are highly-conserved based on ConSurf analysis. 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). 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. . Chen ZJ, Sreedasyam A, Ando A, Song Q, De Santiago LM, Hulse-Kemp AM, et al., Schmutz J. 2020. Genomic diversifications of five Gossypium allopolyploid species and their impact on cotton improvement. Nat Genet 52: 525-533. PubMed ID: 32313247 Hou H, Erickson J, Meservy J, Schultz EA. 2010. FORKED1 encodes a PH domain protein that is required for PIN1 localization in developing leaf veins. Plant J 63: 960-73. PubMed ID: 20626652 Le Huray KIP, Wang H, Sobott F, Kalli AC. 2022. Systematic simulation of the interactions of pleckstrin homology domains with membranes. Sci Adv 8: eabn6992. PubMed ID: 35857458 Thomas CC, Deak M, Alessi DR, van Aalten DM. 2002. High-resolution structure of the pleckstrin homology domain of protein kinase b/akt bound to phosphatidylinositol (3,4,5)-trisphosphate. Curr Biol 12: 1256-62. PubMed ID: 12176338 References
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