Infrared Spectroscopic Observation of a G-C+Hoogsteen Base Pair in the DNA:TATA-Box Binding Protein Complex Under Solution Conditions.
Stelling, A.L., Liu, A.Y., Zeng, W., Salinas, R., Schumacher, M.A., Al-Hashimi, H.M.(2019) Angew Chem Int Ed Engl 58: 12010-12013
- PubMed: 31268220 
- DOI: https://doi.org/10.1002/anie.201902693
- Primary Citation of Related Structures:  
6NJQ - PubMed Abstract: 
Hoogsteen DNA base pairs (bps) are an alternative base pairing to canonical Watson-Crick bps and are thought to play important biochemical roles. Hoogsteen bps have been reported in a handful of X-ray structures of protein-DNA complexes. However, there are several examples of Hoogsteen bps in crystal structures that form Watson-Crick bps when examined under solution conditions. Furthermore, Hoogsteen bps can sometimes be difficult to resolve in DNA:protein complexes by X-ray crystallography due to ambiguous electron density and by solution-state NMR spectroscopy due to size limitations. Here, using infrared spectroscopy, we report the first direct solution-state observation of a Hoogsteen (G-C + ) bp in a DNA:protein complex under solution conditions with specific application to DNA-bound TATA-box binding protein. These results support a previous assignment of a G-C + Hoogsteen bp in the complex, and indicate that Hoogsteen bps do indeed exist under solution conditions in DNA:protein complexes.
Organizational Affiliation: 
Department of Biochemistry, Duke University Medical Center, Durham, NC, 27710, USA.