Published online 16 August 2005
Article |
Not so crystal clear: the structure of the human telomere G-quadruplex in solution differs from that present in a crystal
Department of Biochemistry, University of Mississippi Medical Center 2500 North State Street, Jackson, MS 39216-4505, USA 1James Graham Brown Cancer Center, University of Louisville 529 South Jackson Street, Louisville, KY 40202, USA
*To whom correspondence should be addressed. Tel: +1 502 852 1172; Fax: +1 502 852 1153; Email: j.chaires{at}louisville.edu
Received July 22, 2005. Revised August 4, 2005. Accepted August 4, 2005.
The structure of human telomere DNA is of intense interest because of its role in the biology of both cancer and aging. The sequence [5'-AGGG(TTAGGG)3] has been used as a model for telomere DNA in both NMR and X-ray crystallographic studies, the results of which show dramatically different structures. In Na+ solution, NMR revealed an antiparallel G-quadruplex structure that featured both diagonal and lateral TTA loops. Crystallographic studies in the presence of K+ revealed a flattened, propeller-shaped structure featuring a parallel-stranded G-quadruplex with symmetrical external TTA loops. We report the results of biophysical experiments in solution and computational studies that are inconsistent with the reported crystal structure, indicating that a different structure exists in K+ solutions. Sedimentation coefficients were determined experimentally in both Na+ and K+ solutions and were compared with values calculated using bead models for the reported NMR and crystal structures. Although the solution NMR structure accurately predicted the observed S-value in Na+ solution, the crystal structure predicted an S-value that differed dramatically from that experimentally observed in K+ solution. The environments of loop adenines were probed by quantitative fluorescence studies using strategic and systematic single-substitutions of 2-aminopurine for adenine bases. Both fluorescence intensity and quenching experiments in K+ yielded results at odds with quantitative predictions from the reported crystal structure. Circular dichroism and fluorescence quenching studies in the presence of the crowding agent polyethylene glycol showed dramatic changes in the quadruplex structure in K+ solutions, but not in Na+ solutions, suggesting that the crystal environment may have selected for a particular conformational form. Molecular dynamics simulations were performed to yield model structures for the K+ quadruplex form that are consistent with our biophysical results and with previously reported chemical modification studies. These models suggest that the biologically relevant structure of the human telomere quadruplex in K+ solution is not the one determined in the published crystalline state.
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
K. W. Lim, P. Alberti, A. Guedin, L. Lacroix, J.-F. Riou, N. J. Royle, J.-L. Mergny, and A. T. Phan Sequence variant (CTAGGG)n in the human telomere favors a G-quadruplex structure containing a G{middle dot}C{middle dot}G{middle dot}C tetrad Nucleic Acids Res., October 1, 2009; 37(18): 6239 - 6248. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Renciuk, I. Kejnovska, P. Skolakova, K. Bednarova, J. Motlova, and M. Vorlickova Arrangements of human telomere DNA quadruplex in physiologically relevant K+ solutions Nucleic Acids Res., October 1, 2009; 37(19): 6625 - 6634. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. G. T. Su, H. Fang, M. L. Gross, and J.-S. A. Taylor Photocrosslinking of human telomeric G-quadruplex loops by anti cyclobutane thymine dimer formation PNAS, August 4, 2009; 106(31): 12861 - 12866. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Kypr, I. Kejnovska, D. Renciuk, and M. Vorlickova Circular dichroism and conformational polymorphism of DNA Nucleic Acids Res., April 1, 2009; 37(6): 1713 - 1725. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. N. Lane, J. B. Chaires, R. D. Gray, and J. O. Trent Stability and kinetics of G-quadruplex structures Nucleic Acids Res., October 1, 2008; 36(17): 5482 - 5515. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Masuda-Sasa, P. Polaczek, X. P. Peng, L. Chen, and J. L. Campbell Processing of G4 DNA by Dna2 Helicase/Nuclease and Replication Protein A (RPA) Provides Insights into the Mechanism of Dna2/RPA Substrate Recognition J. Biol. Chem., September 5, 2008; 283(36): 24359 - 24373. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. D. Gray and J. B. Chaires Kinetics and mechanism of K+- and Na+-induced folding of models of human telomeric DNA into G-quadruplex structures Nucleic Acids Res., July 1, 2008; 36(12): 4191 - 4203. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Sandin, K. Borjesson, H. Li, J. Martensson, T. Brown, L. M. Wilhelmsson, and B. Albinsson Characterization and use of an unprecedentedly bright and structurally non-perturbing fluorescent DNA base analogue Nucleic Acids Res., January 17, 2008; 36(1): 157 - 167. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. J. Patel, A. T. Phan, and V. Kuryavyi Human telomere, oncogenic promoter and 5'-UTR G-quadruplexes: diverse higher order DNA and RNA targets for cancer therapeutics Nucleic Acids Res., December 3, 2007; 35(22): 7429 - 7455. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. T. Phan, V. Kuryavyi, K. N. Luu, and D. J. Patel Structure of two intramolecular G-quadruplexes formed by natural human telomere sequences in K+ solution Nucleic Acids Res., October 8, 2007; 35(19): 6517 - 6525. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Dai, M. Carver, C. Punchihewa, R. A. Jones, and D. Yang Structure of the Hybrid-2 type intramolecular human telomeric G-quadruplex in K+ solution: insights into structure polymorphism of the human telomeric sequence Nucleic Acids Res., August 1, 2007; 35(15): 4927 - 4940. [Abstract] [Full Text] [PDF] |
||||
![]() |
C.-C. Chang, C.-W. Chien, Y.-H. Lin, C.-C. Kang, and T.-C. Chang Investigation of spectral conversion of d(TTAGGG)4 and d(TTAGGG)13 upon potassium titration by a G-quadruplex recognizer BMVC molecule Nucleic Acids Res., May 14, 2007; 35(9): 2846 - 2860. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. M. Barbieri, A. R. Srinivasan, S. G. Rzuczek, J. E. Rice, E. J. LaVoie, and D. S. Pilch Defining the mode, energetics and specificity with which a macrocyclic hexaoxazole binds to human telomeric G-quadruplex DNA Nucleic Acids Res., May 11, 2007; 35(10): 3272 - 3286. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Dai, C. Punchihewa, A. Ambrus, D. Chen, R. A. Jones, and D. Yang Structure of the intramolecular human telomeric G-quadruplex in potassium solution: a novel adenine triple formation Nucleic Acids Res., April 19, 2007; (2007) gkm009v2. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Podbevsek, N. V. Hud, and J. Plavec NMR evaluation of ammonium ion movement within a unimolecular G-quadruplex in solution Nucleic Acids Res., April 11, 2007; (2007) gkm138v2. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Burge, G. N. Parkinson, P. Hazel, A. K. Todd, and S. Neidle Quadruplex DNA: sequence, topology and structure Nucleic Acids Res., November 14, 2006; 34(19): 5402 - 5415. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. T. Phan, K. N. Luu, and D. J. Patel Different loop arrangements of intramolecular human telomeric (3+1) G-quadruplexes in K+ solution Nucleic Acids Res., November 14, 2006; 34(19): 5715 - 5719. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Ambrus, D. Chen, J. Dai, T. Bialis, R. A. Jones, and D. Yang Human telomeric sequence forms a hybrid-type intramolecular G-quadruplex structure with mixed parallel/antiparallel strands in potassium solution. Nucleic Acids Res., January 1, 2006; 34(9): 2723 - 2735. [Abstract] [Full Text] [PDF] |
||||
![]() |
J.-L. Mergny, J. Li, L. Lacroix, S. Amrane, and J. B. Chaires Thermal difference spectra: a specific signature for nucleic acid structures Nucleic Acids Res., September 12, 2005; 33(16): e138 - e138. [Abstract] [Full Text] [PDF] |
||||


