2w00
From Proteopedia
Crystal structure of the HsdR subunit of the EcoR124I restriction enzyme in complex with ATP
Structural highlights
FunctionT1R1_ECOLX The restriction (R) subunit of a type I restriction enzyme that recognizes 5'-GAAN(6)RTCG-3' (for EcoR124I) and 5'-GAAN(7)RTCG-3' (for EcoR124II) and cleaves a random distance away (PubMed:2784505). Subunit R is required for both nuclease and ATPase activities, but not for modification (Probable) (PubMed:12654995). After locating an unmethylated 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 (PubMed:15300241). The enzyme undergoes major structural changes to bring the motor domains into contact with DNA, allowing DNA translocation. This prevents DNA access to the catalytic domains of both the R and M subunits, preventing both restriction and methylation (PubMed:32483229). 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).[1] [2] [3] [4] [5] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedType I restriction-modification enzymes act as conventional adenine methylases on hemimethylated DNAs, but unmethylated recognition targets induce them to translocate thousands of base pairs before cleaving distant sites nonspecifically. The first crystal structure of a type I motor subunit responsible for translocation and cleavage suggests how the pentameric translocating complex is assembled and provides a structural framework for translocation of duplex DNA by RecA-like ATPase motors. Structure of the motor subunit of type I restriction-modification complex EcoR124I.,Lapkouski M, Panjikar S, Janscak P, Smatanova IK, Carey J, Ettrich R, Csefalvay E Nat Struct Mol Biol. 2008 Dec 14. PMID:19079266[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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