Type I restriction enzyme EcoR124I/EcoR124II methylase subunit

UniProtKB accession:  P10484

Grouped By:  Matching UniProtKB accession

UniProtKB description:  The subtype gamma methyltransferase (M) subunit of a type I restriction enzyme. The M and S subunits together form a methyltransferase (MTase) that methylates A-3 on the top and bottom strand of the sequence 5'-GAAN(6)RTCG-3' (for EcoR124I) and 5'-GAAN(7)RTCG-3' (for EcoR124II). In the presence of the R subunit the complex can also act as an endonuclease, binding to the same target sequence but cutting the DNA some distance from this site (PubMed:15300241). Whether the DNA is cut or modified depends on the methylation state of the target sequence. When the target site is unmodified, the DNA is cut. When the target site is hemimethylated, the complex acts as a maintenance MTase modifying the DNA so that both strands become methylated (PubMed:12654995, PubMed:32483229). After locating a non-methylated recognition site, the enzyme complex serves as a molecular motor that translocates DNA in an ATP-dependent manner until a collision occurs that triggers cleavage (Probable). The R(1)M(2)S(1) complex translocates an average of 555 bp/second on nicked DNA; the R(2)M(2)S(1) complex translocates at double that speed (PubMed:15300241). The 2 R subunit motors are independent and track along the helical pitch of the DNA, inducing positive supercoiling ahead of themselves (PubMed:15300241).