Evidence that nucleosomes inhibit mismatch repair in eukaryotic cells.
The influence of chromatin structure on DNA metabolic processes, including DNA replication and repair, has been a matter of intensive studies in recent years. Although the human mismatch repair (MMR) reaction has been reconstituted using purified proteins, the influence of chromatin structure on human MMR is unknown. This study examines the interaction between human MutSalpha and a mismatch located within a nucleosome or between two nucleosomes. The results show that, whereas MutSalpha specifically recognizes both types of nucleosomal heteroduplexes, the protein bound the mismatch within a nucleosome with much lower efficiency than a naked heteroduplex or a heterology free of histone proteins but between two nucleosomes. Additionally, MutSalpha displays reduced ATPase- and ADP-binding activity when interacting with nucleosomal heteroduplexes. Interestingly, nucleosomes block ATP-induced MutSalpha sliding along the DNA helix when the mismatch is in between two nucleosomes. These findings suggest that nucleosomes may inhibit MMR in eukaryotic cells. The implications of these findings for our understanding of eukaryotic MMR are discussed.
Li
Feng
F
Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA.
Tian
Lei
L
Gu
Liya
L
Li
Guo-Min
GM
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D053843:DNA Mismatch Repair; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D024202:Electrophoretic Mobility Shift Assay; D005057:Eukaryotic Cells / Q000378:metabolism*; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051719:MutS DNA Mismatch-Binding Protein / Q000378:metabolism; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics / Q000378:metabolism; D009707:Nucleosomes / Q000378:metabolism*; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding
D006657:Histones; D009692:Nucleic Acid Heteroduplexes; D009707:Nucleosomes; D009841:Oligonucleotides; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein