title: High-resolution NMR reveals secondary structure and folding of amino acid transporter from outer chloroplast membrane.
abstract: Solving high-resolution structures for membrane proteins continues to be a daunting challenge in the structural biology community. In this study we report our high-resolution NMR results for a transmembrane protein, outer envelope protein of molar mass 16 kDa (OEP16), an amino acid transporter from the outer membrane of chloroplasts. Three-dimensional, high-resolution NMR experiments on the (13)C, (15)N, (2)H-triply-labeled protein were used to assign protein backbone resonances and to obtain secondary structure information. The results yield over 95% assignment of N, HN, CO, Cα, and Cβ chemical shifts, which is essential for obtaining a high resolution structure from NMR data. Chemical shift analysis from the assignment data reveals experimental evidence for the first time on the location of the secondary structure elements on a per residue basis. In addition T 1Z and T2 relaxation experiments were performed in order to better understand the protein dynamics. Arginine titration experiments yield an insight into the amino acid residues responsible for protein transporter function. The results provide the necessary basis for high-resolution structural determination of this important plant membrane protein.
authors.affiliation: Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, United States of America.
authors.forename: James D
authors.initials: JD
authors.lastname: Zook
authors.forename: Trivikram R
authors.initials: TR
authors.lastname: Molugu
authors.forename: Neil E
authors.initials: NE
authors.lastname: Jacobsen
authors.forename: Guangxin
authors.initials: G
authors.lastname: Lin
authors.forename: Jürgen
authors.initials: J
authors.lastname: Soll
authors.forename: Brian R
authors.initials: BR
authors.lastname: Cherry
authors.forename: Michael F
authors.initials: MF
authors.lastname: Brown
authors.forename: Petra
authors.initials: P
authors.lastname: Fromme
mesh_terms: D026905:Amino Acid Transport Systems / Q000737:chemistry*; D002736:Chloroplasts / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008565:Membrane Proteins / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry*; D017433:Protein Structure, Secondary
chemical_list: D026905:Amino Acid Transport Systems; D008565:Membrane Proteins; D010940:Plant Proteins