3G3X

Crystal structure of spin labeled T4 Lysozyme (T151R1) at 100 K

Summary for 3G3X

• Entry DOI: 10.2210/pdb3g3x/pdb
• Related: 1ZYT 2CUU 3G3V 3G3W
• Descriptor: Lysozyme, S-[(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl] methanesulfonothioate, 2-HYDROXYETHYL DISULFIDE, ... (6 entities in total)
• Functional Keywords: hydrolase, modified cysteine, nitroxide, antimicrobial, bacteriolytic enzyme, glycosidase
• Biological source: Enterobacteria phage T4 (Bacteriophage T4)
• Cellular location: Host cytoplasm : P00720
• Total number of polymer chains: 1
• Total formula weight: 19239.44

Authors

Fleissner, M.R.,Cascio, D.,Hubbell, W.L. (deposition date: 2009-02-02, release date: 2009-05-05, Last modification date: 2024-11-20)

Primary citation

Fleissner, M.R.,Cascio, D.,Hubbell, W.L.
Structural origin of weakly ordered nitroxide motion in spin-labeled proteins.
Protein Sci., 18:893-908, 2009

PubMed Abstract: A disulfide-linked nitroxide side chain (R1) used in site-directed spin labeling of proteins often exhibits an EPR spectrum characteristic of a weakly ordered z-axis anisotropic motion at topographically diverse surface sites, including those on helices, loops and edge strands of beta-sheets. To elucidate the origin of this motion, the first crystal structures of R1 that display simple z-axis anisotropic motion at solvent-exposed helical sites (131 and 151) and a loop site (82) in T4 lysozyme have been determined. Structures of 131R1 and 151R1 determined at cryogenic or ambient temperature reveal an intraresidue C(alpha)--H...S(delta) interaction that immobilizes the disulfide group, consistent with a model in which the internal motions of R1 are dominated by rotations about the two terminal bonds (Columbus, Kálai, Jeko, Hideg, and Hubbell, Biochemistry 2001;40:3828-3846). Remarkably, the 131R1 side chain populates two rotamers equally, but the EPR spectrum reflects a single dominant dynamic population, showing that the two rotamers have similar internal motion determined by the common disulfide-backbone interaction. The anisotropic motion for loop residue 82R1 is also accounted for by a common disulfide-backbone interaction, showing that the interaction does not require a specific secondary structure. If the above observations prove to be general, then significant variations in order and rate for R1 at noninteracting solvent-exposed helical and loop sites can be assigned to backbone motion because the internal motion is essentially constant.

PubMed: 19384990
DOI: 10.1002/pro.96

Experimental method

X-RAY DIFFRACTION (1.8 Å)