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MutT homologue 1 (MTH1) catalyzes the hydrolysis of mutagenic O6-methyl-dGTP

DOI: 10.1093/nar/gky896 DOI Help

Authors: Ann-Sofie Jemth (Karolinska Institutet) , Robert Gustafsson (Stockholm University) , Lars Bräutigam (Karolinska Institutet) , Linda Henriksson (Stockholm University) , Karl S. A. Vallin (Karolinska Institutet) , Antonio Sarno (Norwegian University of Science and Technology; St. Olavs Hospital) , Ingrid Almlöf (Karolinska Institutet) , Evert Homan (Karolinska Institutet) , Azita Rasti (Karolinska Institutet) , Ulrika Warpman berglund (Karolinska Institutet) , Pal Stenmark (Stockholm University) , Thomas Helleday (Karolinska Institutet; University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nucleic Acids Research , VOL 23

State: Published (Approved)
Published: October 2018
Diamond Proposal Number(s): 11265

Open Access Open Access

Abstract: Nucleotides in the free pool are more susceptible to nonenzymatic methylation than those protected in the DNA double helix. Methylated nucleotides like O6-methyl-dGTP can be mutagenic and toxic if incorporated into DNA. Removal of methylated nucleotides from the nucleotide pool may therefore be important to maintain genome integrity. We show that MutT homologue 1 (MTH1) efficiently catalyzes the hydrolysis of O6-methyl-dGTP with a catalytic efficiency similar to that for 8-oxo-dGTP. O6-methyl-dGTP activity is exclusive to MTH1 among human NUDIX proteins and conserved through evolution but not found in bacterial MutT. We present a high resolution crystal structure of human and zebrafish MTH1 in complex with O6-methyl-dGMP. By microinjecting fertilized zebrafish eggs with O6-methyl-dGTP and inhibiting MTH1 we demonstrate that survival is dependent on active MTH1 in vivo. O6-methyl-dG levels are higher in DNA extracted from zebrafish embryos microinjected with O6-methyl-dGTP and inhibition of O6-methylguanine-DNA methyl transferase (MGMT) increases the toxicity of O6-methyl-dGTP demonstrating that O6-methyl-dGTP is incorporated into DNA. MTH1 deficiency sensitizes human cells to the alkylating agent Temozolomide, a sensitization that is more pronounced upon MGMT inhibition. These results expand the cellular MTH1 function and suggests MTH1 also is important for removal of methylated nucleotides from the nucleotide pool.

Diamond Keywords: Enzymes

Subject Areas: Biology and Bio-materials, Medicine
Collaborations: Diamond Manchester

Instruments: I04-1-Macromolecular Crystallography (fixed wavelength)

Other Facilities: ESRF; Max-Lab; BESSY; PETRA; Swiss Light Source

Added On: 15/03/2019 10:04


Discipline Tags:

Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)