TY - JOUR
T1 - Mobility of Histidine Side Chains Analyzed with 15 N NMR Relaxation and Cross-Correlation Data
T2 - Insight into Zinc-Finger-DNA Interactions
AU - Kemme, Catherine A.
AU - Luu, Ross H.
AU - Chen, Chuanying
AU - Pletka, Channing C.
AU - Pettitt, B. Montgomery
AU - Iwahara, Junji
N1 - Funding Information:
This work was supported by Grants R01-GM107590 (to J.I.), R35-GM130326 (to J.I.), and R01-GM066813 (to B.M.P.) from the National Institutes of Health. B.M.P. and C.C. gratefully acknowledge the Robert A. Welch Foundation (H-0037).
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/5/2
Y1 - 2019/5/2
N2 - Due to chemical exchange, the mobility of histidine (His) side chains of proteins is typically difficult to analyze by NMR spectroscopy. Using an NMR approach that is uninfluenced by chemical exchange, we investigated internal motions of the His imidazole NH groups that directly interact with DNA phosphates in the Egr-1 zinc-finger-DNA complex. In this approach, the transverse and longitudinal cross-correlation rates for 15 N chemical shift anisotropy and 15 N- 1 H dipole-dipole relaxation interference were analyzed together with 15 N longitudinal relaxation rates and heteronuclear Overhauser effect data at two magnetic field strengths. We found that the zinc-coordinating His side chains directly interacting with DNA phosphates are strongly restricted in mobility. This makes a contrast to the arginine and lysine side chains that retain high mobility despite their interactions with DNA phosphates in the same complex. The entropic effects of side-chain mobility on the molecular association are discussed.
AB - Due to chemical exchange, the mobility of histidine (His) side chains of proteins is typically difficult to analyze by NMR spectroscopy. Using an NMR approach that is uninfluenced by chemical exchange, we investigated internal motions of the His imidazole NH groups that directly interact with DNA phosphates in the Egr-1 zinc-finger-DNA complex. In this approach, the transverse and longitudinal cross-correlation rates for 15 N chemical shift anisotropy and 15 N- 1 H dipole-dipole relaxation interference were analyzed together with 15 N longitudinal relaxation rates and heteronuclear Overhauser effect data at two magnetic field strengths. We found that the zinc-coordinating His side chains directly interacting with DNA phosphates are strongly restricted in mobility. This makes a contrast to the arginine and lysine side chains that retain high mobility despite their interactions with DNA phosphates in the same complex. The entropic effects of side-chain mobility on the molecular association are discussed.
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U2 - 10.1021/acs.jpcb.9b03132
DO - 10.1021/acs.jpcb.9b03132
M3 - Article
C2 - 30963768
AN - SCOPUS:85065104349
SN - 1089-5647
VL - 123
SP - 3706
EP - 3710
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 17
ER -