Chemical Shifts for the Unusual DNA Structure in Pf1 Bacteriophage from Dynamic-Nuclear-Polarization-Enhanced Solid-State NMR Spectroscopy

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• 作者：Ivan V. Sergeyev ; Loren A. Day ; Amir Goldbourt ; Ann E. McDermott
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：December 21, 2011
• 年：2011
• 卷：133
• 期：50
• 页码：20208-20217
• 全文大小：1328K
• 年卷期：v.133,no.50(December 21, 2011)
• ISSN：1520-5126

文摘

Solid-state NMR spectra, including dynamic nuclear polarization enhanced 400 MHz spectra acquired at 100 K, as well as non-DNP spectra at a variety of field strengths and at temperatures in the range 213鈥?43 K, have allowed the assignment of the ¹³C and ¹⁵N resonances of the unusual DNA structure in the Pf1 virion. The ¹³C chemical shifts of C3鈥?and C5鈥? considered to be key reporters of deoxyribose conformation, fall near or beyond the edges of their respective ranges in available databases. The ¹³C and ¹⁵N chemical shifts of the DNA bases have above-average values for AC4, AC5, CC5, TC2, and TC5, and below average values for AC8, GC8, and GN2, pointing to an absence of Watson鈥揅rick hydrogen bonding, yet the presence of some type of aromatic ring interaction. Crosspeaks between Tyr40 of the coat protein and several DNA atoms suggest that Tyr40 is involved in this ring interaction. In addition, these crosspeak resonances and several deoxyribose resonances are multiply split, presumably through the effects of ordered but differing interactions between capsid protein subunits and each type of nucleotide in each of the two DNA strands. Overall, these observations characterize and support the DNA model proposed by Liu and Day and refined by Tsuboi et al., which calls for the most highly stretched and twisted naturally occurring DNA yet encountered.