Journal
JOURNAL OF MOLECULAR BIOLOGY
Volume 433, Issue 21, Pages -Publisher
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2021.167226
Keywords
silicic acid transport; NIP channel; aquaporin; X-ray crystal structure; molecular dynamics
Categories
Funding
- EPSRC [EP/R029407/1]
- Medical Research Council [MR/N020413/1]
- EPSRC [EP/R029407/1] Funding Source: UKRI
- MRC [MR/N020413/1] Funding Source: UKRI
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This study presents the X-ray crystal structure of the OsNIP2;1 channel from rice, revealing insights into its regulation of silicic acid transport. The results are expected to advance structure-function studies of metalloid porins.
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. (C) 2021 The Authors. Published by Elsevier Ltd.
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