Structural Basis for Silicic Acid Uptake by Higher Plants. Issue 21 (15th October 2021)

• Record Type: Journal Article
• Authors: van den Berg, Bert; Pedebos, Conrado; Bolla, Jani R.; Robinson, Carol V.; Baslé, Arnaud; Khalid, Syma
• Is Part Of: Journal of molecular biology. Volume 433:Issue 21(2021)
• Publication Date: 2021-10-15
• Subjects: silicic acid transport -- NIP channel -- aquaporin -- X-ray crystal structure -- molecular dynamics; NIP Nodulin 26-like Intrinsic Protein -- Si silicon -- MD molecular dynamics; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2021.167226
• Languages: English
• ISSNs: 0022-2836

Abstract

Graphical abstract: Highlights: NIP channels mediate uptake of metalloids such as silicic acid in plants. The first structure of a NIP metalloid porin is reported. OsNIP2;1 has a wide, five-residue extracellular selectivity filter. Molecular dynamics simulations reveal how silicic acid diffuses through OsNIP2;1. Our data will enable detailed structure–function studies of metalloid porins. Abstract: Many of the world's most important food crops such as rice, barley and maize accumulate silicon (Si) to high levels, resulting in better plant growth and crop yields. The first step in Si accumulation is the uptake of silicic acid by the roots, a process mediated by the structurally uncharacterised NIP subfamily of aquaporins, also named metalloid porins. Here, we present the X-ray crystal structure of the archetypal NIP family member from Oryza sativa (OsNIP2;1). The OsNIP2;1 channel is closed in the crystal structure by the cytoplasmic loop D, which is known to regulate channel opening in classical plant aquaporins. The structure further reveals a novel, five-residue extracellular selectivity filter with a large diameter. Unbiased molecular dynamics simulations show a rapid opening of the channel and visualise how silicic acid interacts with the selectivity filter prior to transmembrane diffusion. Our results will enable detailed structure–function studies of metalloid porins, including the basis of their substrate selectivity.