Physical and functional interactions between Werner syndrome helicase and mismatch-repair initiation factors

TY - JOUR

T1 - Physical and functional interactions between Werner syndrome helicase and mismatch-repair initiation factors

AU - Saydam, Nurten

AU - Kanagaraj, Radhakrishnan

AU - Dietschy, Tobias

AU - Garcia, Patrick L

AU - Pena Diaz, Javier

AU - Shevelev, Igor

AU - Stagljar, Igor

AU - Janscak, Pavel

PY - 2007

Y1 - 2007

N2 - Werner syndrome (WS) is a severe recessive disorder characterized by premature aging, cancer predisposition and genomic instability. The gene mutated in WS encodes a bi-functional enzyme called WRN that acts as a RecQ-type DNA helicase and a 3'-5' exonuclease, but its exact role in DNA metabolism is poorly understood. Here we show that WRN physically interacts with the MSH2/MSH6 (MutSalpha), MSH2/MSH3 (MutSbeta) and MLH1/PMS2 (MutLalpha) heterodimers that are involved in the initiation of mismatch repair (MMR) and the rejection of homeologous recombination. MutSalpha and MutSbeta can strongly stimulate the helicase activity of WRN specifically on forked DNA structures with a 3'-single-stranded arm. The stimulatory effect of MutSalpha on WRN-mediated unwinding is enhanced by a G/T mismatch in the DNA duplex ahead of the fork. The MutLalpha protein known to bind to the MutS alpha-heteroduplex complexes has no effect on WRN-mediated DNA unwinding stimulated by MutSalpha, nor does it affect DNA unwinding by WRN alone. Our data are consistent with results of genetic experiments in yeast suggesting that MMR factors act in conjunction with a RecQ-type helicase to reject recombination between divergent sequences.

AB - Werner syndrome (WS) is a severe recessive disorder characterized by premature aging, cancer predisposition and genomic instability. The gene mutated in WS encodes a bi-functional enzyme called WRN that acts as a RecQ-type DNA helicase and a 3'-5' exonuclease, but its exact role in DNA metabolism is poorly understood. Here we show that WRN physically interacts with the MSH2/MSH6 (MutSalpha), MSH2/MSH3 (MutSbeta) and MLH1/PMS2 (MutLalpha) heterodimers that are involved in the initiation of mismatch repair (MMR) and the rejection of homeologous recombination. MutSalpha and MutSbeta can strongly stimulate the helicase activity of WRN specifically on forked DNA structures with a 3'-single-stranded arm. The stimulatory effect of MutSalpha on WRN-mediated unwinding is enhanced by a G/T mismatch in the DNA duplex ahead of the fork. The MutLalpha protein known to bind to the MutS alpha-heteroduplex complexes has no effect on WRN-mediated DNA unwinding stimulated by MutSalpha, nor does it affect DNA unwinding by WRN alone. Our data are consistent with results of genetic experiments in yeast suggesting that MMR factors act in conjunction with a RecQ-type helicase to reject recombination between divergent sequences.

KW - Base Pair Mismatch

KW - Binding Sites

KW - Cell Line

KW - DNA

KW - DNA Repair

KW - DNA Repair Enzymes

KW - DNA-Binding Proteins

KW - Exodeoxyribonucleases

KW - Humans

KW - MutS Homolog 2 Protein

KW - Protein Structure, Tertiary

KW - RecQ Helicases

KW - Two-Hybrid System Techniques

U2 - 10.1093/nar/gkm500

DO - 10.1093/nar/gkm500

M3 - Journal article

C2 - 17715146

SN - 0305-1048

VL - 35

SP - 5706

EP - 5716

JO - Nucleic Acids Research

JF - Nucleic Acids Research

IS - 17

ER -