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N-15 NMR relaxation studies of backbone dynamics in free and steroid-bound Delta(5)-3-ketosteroid isomerase from Pseudomonas testosteroni

Title
N-15 NMR relaxation studies of backbone dynamics in free and steroid-bound Delta(5)-3-ketosteroid isomerase from Pseudomonas testosteroni
Authors
Yun, SGJang, DSKim, DHChoi, KYLee, HC
POSTECH Authors
Choi, KY
Date Issued
Jan-2001
Publisher
AMER CHEMICAL SOC
Abstract
The backbone dynamics of Delta (5)-3-ketosteroid isomerase (KSI) from Pseudomonas testosteroni has been studied in free enzyme and its complex with a steroid ligand, 19-nortestosterone hemisuccinate (19-NTHS), by N-15 relaxation measurements. The relaxation data were analyzed using the model-free formalism to extract the model-free parameters (S-2, tau (e), and R-ex) and the overall rotational correlation time (tau (m)) The rotational correlation times were 19.23 +/- 0.08 and 17.08 +/- 0.07 ns with the diffusion anisotropies (D parallel to /D perpendicular to) of 1.26 +/- 0.03 and 1.25 +/- 0.03 for the free and steroid-bound KSI, respectively. The binding of 19-NTHS to free KSI causes a slight increase in the order parameters (S-2) for a number of residues, which are located mainly in helix Al and strand B4. However, the majority of the residues exhibit reduced order parameters upon ligand binding. In particular, strands B3, B5, and B6, which have most of the residues involved in the dimer interaction, have the reduced order parameters in the steroid-bound KSI, indicating the increased high-frequency (pico- to nanosecond) motions in the intersubunit region of this homodimeric enzyme. Our results differ from those of previous studies on the backbone dynamics of monomeric proteins, in which high-frequency internal motions are typically restricted upon ligand binding.
Keywords
NUCLEAR-MAGNETIC-RESONANCE; CHEMICAL-SHIFT ANISOTROPY; MODEL-FREE APPROACH; ROTATIONAL DIFFUSION; LIGAND-BINDING; CROSS-CORRELATION; SH3 DOMAIN; SPECTROSCOPY; PROTEIN; C-13
URI
http://oasis.postech.ac.kr/handle/2014.oak/19610
DOI
10.1021/BI0023192
ISSN
0006-2960
Article Type
Article
Citation
BIOCHEMISTRY, vol. 40, no. 13, page. 3967 - 3973, 2001-01
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최관용CHOI, KWAN YONG
Div of Integrative Biosci & Biotech
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