TY - JOUR
T1 - Molecular and structural characterization of disease-associated APE1 polymorphisms
AU - Whitaker, Amy
AU - Stark, Wesley J.
AU - Flynn, Tony S.
AU - Freudenthal, Bret D.
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/7/1
Y1 - 2020/7/1
N2 - Under conditions of oxidative stress, reactive oxygen species (ROS) continuously assault the structure of DNA resulting in oxidation and fragmentation of the nucleobases. When the nucleobase structure is altered, its base-pairing properties may also be altered, promoting mutations. Consequently, oxidative DNA damage is a major source of the mutation load that gives rise to numerous human maladies, including cancer. Base excision repair (BER) is the primary pathway tasked with removing and replacing mutagenic DNA base damage. Apurinic/apyrimidinic endonuclease 1 (APE1) is a central enzyme with AP-endonuclease and 3′ to 5′ exonuclease functions during BER, and therefore is key to maintenance of genome stability. Polymorphisms, or SNPs, in the gene encoding APE1 (APEX1) have been identified among specific human populations and result in variants of APE1 with modified function. These defects in APE1 potentially result in impaired DNA repair capabilities and consequently an increased risk of disease for individuals within these populations. In the present study, we determined the X-ray crystal structures of three prevalent disease-associated APE1 SNPs (D148E, L104R, and R237C). Each APE1 SNP results in unique localized changes in protein structure, including protein dynamics and DNA binding contacts. Combined with comprehensive biochemical characterization, including pre-steady-state kinetic and DNA binding analyses, variant APE1:DNA complex structures with both AP-endonuclease and exonuclease substrates were analyzed to elucidate how these SNPs might perturb the two major repair functions employed by APE1 during BER.
AB - Under conditions of oxidative stress, reactive oxygen species (ROS) continuously assault the structure of DNA resulting in oxidation and fragmentation of the nucleobases. When the nucleobase structure is altered, its base-pairing properties may also be altered, promoting mutations. Consequently, oxidative DNA damage is a major source of the mutation load that gives rise to numerous human maladies, including cancer. Base excision repair (BER) is the primary pathway tasked with removing and replacing mutagenic DNA base damage. Apurinic/apyrimidinic endonuclease 1 (APE1) is a central enzyme with AP-endonuclease and 3′ to 5′ exonuclease functions during BER, and therefore is key to maintenance of genome stability. Polymorphisms, or SNPs, in the gene encoding APE1 (APEX1) have been identified among specific human populations and result in variants of APE1 with modified function. These defects in APE1 potentially result in impaired DNA repair capabilities and consequently an increased risk of disease for individuals within these populations. In the present study, we determined the X-ray crystal structures of three prevalent disease-associated APE1 SNPs (D148E, L104R, and R237C). Each APE1 SNP results in unique localized changes in protein structure, including protein dynamics and DNA binding contacts. Combined with comprehensive biochemical characterization, including pre-steady-state kinetic and DNA binding analyses, variant APE1:DNA complex structures with both AP-endonuclease and exonuclease substrates were analyzed to elucidate how these SNPs might perturb the two major repair functions employed by APE1 during BER.
KW - Catalytic Domain
KW - Crystallography, X-Ray
KW - DNA Damage
KW - DNA Repair
KW - DNA-(Apurinic or Apyrimidinic Site) Lyase/genetics
KW - DNA/metabolism
KW - Genetic Predisposition to Disease
KW - Humans
KW - Kinetics
KW - Mutation
KW - Neoplasms/enzymology
KW - Polymorphism, Single Nucleotide
KW - Protein Conformation
UR - http://www.scopus.com/inward/record.url?scp=85085018011&partnerID=8YFLogxK
UR - https://pubmed.ncbi.nlm.nih.gov/32454397/
U2 - 10.1016/j.dnarep.2020.102867
DO - 10.1016/j.dnarep.2020.102867
M3 - Article
C2 - 32454397
SN - 1568-7864
VL - 91-92
SP - 102867
JO - DNA Repair
JF - DNA Repair
M1 - 102867
ER -