2gb7: Difference between revisions

Line 4:

==Overview==

Restricion endonuclease Ecl18kI is specific for the sequence /CCNGG and, cleaves it before the outer C to generate 5 nt 5'-overhangs. It has been, suggested that Ecl18kI is evolutionarily related to NgoMIV, a 6-bp cutter, that cleaves the sequence G/CCGGC and leaves 4 nt 5'-overhangs. Here, we, report the crystal structure of the Ecl18kI-DNA complex at 1.7 A, resolution and compare it with the known structure of the NgoMIV-DNA, complex. We find that Ecl18kI flips both central nucleotides within the, CCNGG sequence and buries the extruded bases in pockets within the, protein. Nucleotide flipping disrupts Watson-Crick base pairing, induces a, kink in the DNA and shifts the DNA register by 1 bp, making the distances, between scissile phosphates in the Ecl18kI and NgoMIV cocrystal structures, nearly identical. Therefore, the two enzymes can use a conserved DNA, recognition module, yet recognize different sequences, and form, superimposable dimers, yet generate different cleavage patterns. Hence, Ecl18kI is the first example of a restriction endonuclease that flips, nucleotides to achieve specificity for its recognition site.

Restricion endonuclease Ecl18kI is specific for the sequence /CCNGG and cleaves it before the outer C to generate 5 nt 5'-overhangs. It has been suggested that Ecl18kI is evolutionarily related to NgoMIV, a 6-bp cutter that cleaves the sequence G/CCGGC and leaves 4 nt 5'-overhangs. Here, we report the crystal structure of the Ecl18kI-DNA complex at 1.7 A resolution and compare it with the known structure of the NgoMIV-DNA complex. We find that Ecl18kI flips both central nucleotides within the CCNGG sequence and buries the extruded bases in pockets within the protein. Nucleotide flipping disrupts Watson-Crick base pairing, induces a kink in the DNA and shifts the DNA register by 1 bp, making the distances between scissile phosphates in the Ecl18kI and NgoMIV cocrystal structures nearly identical. Therefore, the two enzymes can use a conserved DNA recognition module, yet recognize different sequences, and form superimposable dimers, yet generate different cleavage patterns. Hence, Ecl18kI is the first example of a restriction endonuclease that flips nucleotides to achieve specificity for its recognition site.

==About this Structure==

Line 18:

[[Category: Manakova, E.]]

[[Category: Siksnys, V.]]

[[Category: Szczepanowski, R.H.]]

[[Category: Szczepanowski, R H.]]

[[Category: Tamulaitis, G.]]

[[Category: base extrusion]]

Line 25:

[[Category: type ii restriction endonuclease]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on ~~Tue Jan~~ 29 ~~19:55~~:40 2008''

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:29:57 2008''

Navigation menu

Page actions

Page actions

Personal tools

Navigation

Search

Tools

@@ Line 4: / Line 4: @@
 ==Overview==
-Restricion endonuclease Ecl18kI is specific for the sequence /CCNGG and, cleaves it before the outer C to generate 5 nt 5'-overhangs. It has been, suggested that Ecl18kI is evolutionarily related to NgoMIV, a 6-bp cutter, that cleaves the sequence G/CCGGC and leaves 4 nt 5'-overhangs. Here, we, report the crystal structure of the Ecl18kI-DNA complex at 1.7 A, resolution and compare it with the known structure of the NgoMIV-DNA, complex. We find that Ecl18kI flips both central nucleotides within the, CCNGG sequence and buries the extruded bases in pockets within the, protein. Nucleotide flipping disrupts Watson-Crick base pairing, induces a, kink in the DNA and shifts the DNA register by 1 bp, making the distances, between scissile phosphates in the Ecl18kI and NgoMIV cocrystal structures, nearly identical. Therefore, the two enzymes can use a conserved DNA, recognition module, yet recognize different sequences, and form, superimposable dimers, yet generate different cleavage patterns. Hence, Ecl18kI is the first example of a restriction endonuclease that flips, nucleotides to achieve specificity for its recognition site.
+Restricion endonuclease Ecl18kI is specific for the sequence /CCNGG and cleaves it before the outer C to generate 5 nt 5'-overhangs. It has been suggested that Ecl18kI is evolutionarily related to NgoMIV, a 6-bp cutter that cleaves the sequence G/CCGGC and leaves 4 nt 5'-overhangs. Here, we report the crystal structure of the Ecl18kI-DNA complex at 1.7 A resolution and compare it with the known structure of the NgoMIV-DNA complex. We find that Ecl18kI flips both central nucleotides within the CCNGG sequence and buries the extruded bases in pockets within the protein. Nucleotide flipping disrupts Watson-Crick base pairing, induces a kink in the DNA and shifts the DNA register by 1 bp, making the distances between scissile phosphates in the Ecl18kI and NgoMIV cocrystal structures nearly identical. Therefore, the two enzymes can use a conserved DNA recognition module, yet recognize different sequences, and form superimposable dimers, yet generate different cleavage patterns. Hence, Ecl18kI is the first example of a restriction endonuclease that flips nucleotides to achieve specificity for its recognition site.
 ==About this Structure==
@@ Line 18: / Line 18: @@
 [[Category: Manakova, E.]]
 [[Category: Siksnys, V.]]
-[[Category: Szczepanowski, R.H.]]
+[[Category: Szczepanowski, R H.]]
 [[Category: Tamulaitis, G.]]
 [[Category: base extrusion]]
@@ Line 25: / Line 25: @@
 [[Category: type ii restriction endonuclease]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jan 29 19:55:40 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:29:57 2008''