Title: The first crystal structures of hybrid and parallel four-tetrad intramolecular G-quadruplexes

Journal Article · · Nucleic Acids Research

Abstract G-quadruplexes (GQs) are non-canonical DNA structures composed of stacks of stabilized G-tetrads. GQs play an important role in a variety of biological processes and may form at telomeres and oncogene promoters among other genomic locations. Here, we investigate nine variants of telomeric DNA from Tetrahymena thermophila with the repeat (TTGGGG)n. Biophysical data indicate that the sequences fold into stable four-tetrad GQs which adopt multiple conformations according to native PAGE. Excitingly, we solved the crystal structure of two variants, TET25 and TET26. The two variants differ by the presence of a 3′-T yet adopt different GQ conformations. TET25 forms a hybrid [3 + 1] GQ and exhibits a rare 5′-top snapback feature. Consequently, TET25 contains four loops: three lateral (TT, TT, and GTT) and one propeller (TT). TET26 folds into a parallel GQ with three TT propeller loops. To the best of our knowledge, TET25 and TET26 are the first reported hybrid and parallel four-tetrad unimolecular GQ structures. The results presented here expand the repertoire of available GQ structures and provide insight into the intricacy and plasticity of the 3D architecture adopted by telomeric repeats from T. thermophila and GQs in general.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Organization:
National Institutes of Health (NIH); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
Grant/Contract Number:
AC02-06CH11357
OSTI ID:
1846461
Journal Information:
Nucleic Acids Research, Journal Name: Nucleic Acids Research Journal Issue: 5 Vol. 50; ISSN 0305-1048
Publisher:
Oxford University PressCopyright Statement
Country of Publication:
United Kingdom
Language:
English

References (57)

G-Quadruplex Secondary Structure Obtained from Circular Dichroism Spectroscopy journal April 2018
A Minimal Sequence for Left‐Handed G‐Quadruplex Formation journal February 2019
Monomer-Dimer Equilibrium for the 5′-5′ Stacking of Propeller-Type Parallel-Stranded G-Quadruplexes: NMR Structural Study journal September 2012
Solution Structure of a Parallel-stranded G-Quadruplex DNA journal December 1993
Solution Structure of a Parallel-stranded Tetraplex Formed by d(TG4T) in the Presence of Sodium Ions by Nuclear Magnetic Resonance Spectroscopy journal October 1994
The crystal structure of a parallel-stranded guanine tetraplex at 0.95Å resolution journal October 1997
Solution structure of the Tetrahymena telomeric repeat d(T2G4)4 G-tetraplex journal December 1994
G-quadruplex: Flexible conformational changes by cations, pH, crowding and its applications to biosensing journal April 2021
Telomeric repeat mutagenicity in human somatic cells is modulated by repeat orientation and G-quadruplex stability journal November 2010
Two-repeat Tetrahymena Telomeric d(TGGGGTTGGGGT) Sequence Interconverts Between Asymmetric Dimeric G-quadruplexes in Solution journal April 2004
Tetrahymena thermophila, a unicellular eukaryote with separate germline and somatic genomes journal July 2011
DNA quadruplex folding formalism – A tutorial on quadruplex topologies journal November 2013
Structure and stability of sodium and potassium complexes of dT4G4 and dT4G4T journal March 1992
Structure, Energetics, and Dynamics of the Nucleic Acid Base Pairs:  Nonempirical Ab Initio Calculations journal November 1999
Loop-Length-Dependent Folding of G-Quadruplexes journal November 2004
Structure of an Unprecedented G-Quadruplex Scaffold in the Human c-kit Promoter journal April 2007
Optimized End-Stacking Provides Specificity of N -Methyl Mesoporphyrin IX for Human Telomeric G-Quadruplex DNA journal December 2012
Bulges in G-Quadruplexes: Broadening the Definition of G-Quadruplex-Forming Sequences journal March 2013
Guided Assembly of Tetramolecular G-Quadruplexes journal June 2013
NMR study of parallel-stranded tetraplex formation by the hexadeoxynucleotide d(TG4T) journal November 1992
High-throughput sequencing of DNA G-quadruplex structures in the human genome journal July 2015
Small-molecule interaction with a five-guanine-tract G-quadruplex structure from the human MYC promoter journal July 2005
Machine learning model for sequence-driven DNA G-quadruplex formation journal November 2017
Extension of G-quadruplex DNA by ciliate telomerase journal March 2006
Structure of a left-handed DNA G-quadruplex journal February 2015
Combinatorially selected guanosine-quartet structure is a potent inhibitor of human immunodeficiency virus envelope-mediated cell fusion. journal February 1994
Topology-based classification of tetrads and quadruplex structures journal October 2019
G-overhang dynamics at Tetrahymena telomeres journal August 2001
Hexahydrated magnesium ions bind in the deep major groove and at the outer mouth of A-form nucleic acid duplexes journal April 2000
Intra-locked G-quadruplex structures formed by irregular DNA G-rich motifs journal February 2020
Water spines and networks in G-quadruplex structures journal December 2020
Phosphorylation at 5' end of guanosine stretches inhibits dimerization of G-quadruplexes and formation of a G-quadruplex interferes with the enzymatic activities of DNA enzymes journal August 2004
Human telomere, oncogenic promoter and 5'-UTR G-quadruplexes: diverse higher order DNA and RNA targets for cancer therapeutics journal November 2007
Stability of telomeric G-quadruplexes journal December 2010
How long is too long? Effects of loop size on G-quadruplex stability journal July 2010
Stacking of G-quadruplexes: NMR structure of a G-rich oligonucleotide with potential anti-HIV and anticancer activity† journal August 2011
Interaction of human telomeric DNA with N- methyl mesoporphyrin IX journal February 2012
Loop flexibility in human telomeric quadruplex small-molecule complexes journal May 2015
Solution structure of a DNA quadruplex containing ALS and FTD related GGGGCC repeat stabilized by 8-bromodeoxyguanosine substitution journal August 2015
G-quadruplex structure of an anti-proliferative DNA sequence journal May 2017
Quadruplexes in ‘Dicty’: crystal structure of a four-quartet G-quadruplex formed by G-rich motif found in the Dictyostelium discoideum genome journal April 2018
Loop permutation affects the topology and stability of G-quadruplexes journal September 2018
Protein Data Bank: the single global archive for 3D macromolecular structure data journal October 2018
NMR solution and X-ray crystal structures of a DNA molecule containing both right- and left-handed parallel-stranded G-quadruplexes journal June 2019
Thermal difference spectra: a specific signature for nucleic acid structures journal September 2005
A graphical user interface to the CCP 4 program suite journal June 2003
Features and development of Coot journal March 2010
The CCP4 suite programs for protein crystallography journal September 1994
HELIX: a new modular nucleic acid crystallization screen journal May 2014
CheckMyMetal : a macromolecular metal-binding validation tool journal February 2017
Macromolecular structure determination using X-rays, neutrons and electrons: recent developments in Phenix journal October 2019
Encoding canonical DNA quadruplex structure journal August 2018
Telomeric G-Quadruplexes: From Human to Tetrahymena Repeats journal January 2017
A Parallel G Quadruplex-Binding Protein Regulates the Boundaries of DNA Elimination Events of Tetrahymena thermophila journal March 2016
Biophysical and X-ray structural studies of the (GGGTT)3GGG G-quadruplex in complex with N-methyl mesoporphyrin IX journal November 2020
Classification of G-Quadruplex DNA on the Basis of the Quadruplex Twist Angle and Planarity of G-Quartets journal December 2010
Metal Cations in G-Quadruplex Folding and Stability journal September 2016