Structural and functional characterization of a novel acid phosphatase: Arabidopsis thylakoid lumen protein AtTLP18.3
Date Issued
2014
Date
2014
Author(s)
Wu, Hsin-Yi
Abstract
AtTLP18.3 is a thylakoid lumen protein with 285 amino acids. The protein can be divided into three regions based on sequence analysis: a chloroplast transit peptide, a domain of unknown function (DUF477) and a transmenebrane α-helix (TMH). Previous studies indicated that the AtTLP18.3 protein is an auxiliary protein of photosystem II (PSII) repair cycle. In order to clarify the possible molecular function of the AtTLP18.3 protein, the crystal structures of the truncated AtTLP18.3 without targeting signal and TMH were resolved. Since there is no any methionine residue in the truncated AtTLP18.3 protein, we combined the prediction of secondary structure and solvent accessibility and selected leucine (L128M) and isolecine (I159M) residues for methionine substitution. The crystals of native and double mutated AtTLP18.3 shows isomorphous in space group P212121 with unit-cell parameters a = 46.9, b = 49.8, c =76.7 Å, α=β=γ=90°. Finally, the structure of mutant was resolved at a resolution 2.6 Å using single-wavelength anomalous dispersion method, and the native structure was resolved at 1.6 Å resolution. For further structural comparison, the native structure of truncated AtTLP18.3 was submitted to the CATH, DALI and MATRAS database to search similar folding of protein with known function. The results showed that the structure of AtTLP18.3 resembled to various inorganic pyrophosphatase. The enzymatic activity of AtTLP18.3 was further identified by alkaline/acid phosphatase assay. Therefore, we proposed that the function of AtTLP18.3 will act as phosphatase to remove the phosphate group from damage protein for repair cycle.
Subjects
新穎酸性磷解酶
類囊體內腔蛋白
Type
thesis
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