MED1, a novel human methyl-CpG-binding endonuclease, interacts with DNA mismatch repair protein MLH1.
The DNA mismatch repair (MMR) is a specialized system, highly conserved throughout evolution, involved in the maintenance of genomic integrity. To identify novel human genes that may function in MMR, we employed the yeast interaction trap. Using the MMR protein MLH1 as bait, we cloned MED1. The MED1 protein forms a complex with MLH1, binds to methyl-CpG-containing DNA, has homology to bacterial DNA repair glycosylases/lyases, and displays endonuclease activity. Transfection of a MED1 mutant lacking the methyl-CpG-binding domain (MBD) is associated with microsatellite instability (MSI). These findings suggest that MED1 is a novel human DNA repair protein that may be involved in MMR and, as such, may be a candidate eukaryotic homologue of the bacterial MMR endonuclease, MutH. In addition, these results suggest that cytosine methylation may play a role in human DNA repair.
Bellacosa
A
A
Divisions of Population Science, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, PA 19111, USA. A_Bellacosa@fccc.edu
Cicchillitti
L
L
Schepis
F
F
Riccio
A
A
Yeung
A T
AT
Matsumoto
Y
Y
Golemis
E A
EA
Genuardi
M
M
Neri
G
G
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D020137:Base Pair Mismatch; D001483:Base Sequence; D002352:Carrier Proteins; D002460:Cell Line; D003001:Cloning, Molecular; D004260:DNA Repair; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D004706:Endodeoxyribonucleases; C118712:MBD4 protein, human; D000070957:MutL Protein Homolog 1