title: Cotton plasma membrane intrinsic protein 2s (PIP2s) selectively interact to regulate their water channel activities and are required for fibre development.
abstract: Aquaporins are thought to be associated with water transport and play important roles in cotton (Gossypium hirsutum) fibre elongation. Among aquaporins, plasma membrane intrinsic proteins (PIPs) constitute a plasma-membrane-specific subfamily and are further subdivided into PIP1 and PIP2 groups. In this study, four fibre-preferential GhPIP2 genes were functionally characterized. The selective interactions among GhPIP2s and their interaction proteins were studied in detail to elucidate the molecular mechanism of cotton fibre development. GhPIP2;3 interacted with GhPIP2;4 and GhPIP2;6, but GhPIP2;6 did not interact with GhPIP2;4. Coexpression of GhPIP2;3/2;4 or GhPIP2;3/2;6 resulted in a positive cooperative effect which increased the permeability coefficient of oocytes, while GhPIP2;4/2;6 did not. GhBCP2 (a blue copper-binding protein) inhibited GhPIP2;6 water channel activity through their interaction. Overexpression of GhPIP2 genes in yeast induced longitudinal growth of the host cells. By contrast, knockdown of expression of GhPIP2 genes in cotton by RNA interference markedly hindered fibre elongation. In conclusion, GhPIP2 proteins are the primary aquaporin isoforms in fibres. They selectively form hetero-oligomers in order to regulate their activities to meet the requirements for rapid fibre elongation.
authors: Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Sciences, Central China Normal University, Wuhan, China.
authors: Deng-Di
authors: DD
authors: Li
authors: Xiang-Mei
authors: XM
authors: Ruan
authors: Jie
authors: J
authors: Zhang
authors: Ya-Jie
authors: YJ
authors: Wu
authors: Xiu-Lan
authors: XL
authors: Wang
authors: Xue-Bao
authors: XB
authors: Li
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D032561:Cotton Fiber; D015536:Down-Regulation; D005453:Fluorescence; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D017343:Genes, Plant / Q000235:genetics; D003368:Gossypium / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012568:Schizosaccharomyces / Q000235:genetics; D013347:Subcellular Fractions / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; C110065:major intrinsic protein, plant
keywords: aquaporin; coexpression; cotton (Gossypium hirsutum); fibre development; protein-protein interaction; suppression of gene expression