Academic
Publications
A novel endonuclease mechanism directly visualized for I-PpoI

A novel endonuclease mechanism directly visualized for I-PpoI,10.1038/70027,Nature Structural Biology,Eric A. Galburt,Brett Chevalier,Weiliang Tang,Me

A novel endonuclease mechanism directly visualized for I-PpoI   (Citations: 45)
BibTex | RIS | RefWorks Download
A novel mechanism of DNA endonucleolytic cleavage has been visualized for the homing endonuclease I-PpoI by trapping the uncleaved enzyme–substrate complex and comparing it to the previously visualized product complex. This enzyme employs a unique single metal mechanism. A magnesium ion is coordinated by an asparagine residue and two DNA oxygen atoms and stabilizes the phosphoanion transition state and the 3'oxygen leaving group. A hydrolytic water molecule is activated by a histidine residue for an in-line attack on the scissile phosphate. A strained enzyme–substrate–metal complex is formed before cleavage, then relaxed during the reaction.
Journal: Nature Structural Biology - NATURE STRUCT BIOLOGY , vol. 6, no. 12, pp. 1096-1099, 1999
Cumulative Annual
View Publication
The following links allow you to view full publications. These links are maintained by other sources not affiliated with Microsoft Academic Search.
    • ...I-PpoI (12,13) and I-HmuI (14)] and Holliday junction resolvases [e.g...
    • ...The bba-Me region contains a strictly conserved histidine residue that activates a water molecule for incorporation into the DNA substrate (12)...
    • ...As in a previous structure of a bba-Me nuclease with substrate DNA (12), the position of the active site metal ion is taken by a Na+ ion from the crystallization buffer (see ‘Materials and Methods’ section)...
    • ...Here we compare the overall structure of Hpy99I with the structures of I-PpoI as a representative of dimeric bba-Me homing endonucleases (12,13) and T4 endonuclease VII as a representative of Holliday junction resolvases (15) (Figure 8 and Supplementary Figure 2). The overall structures are widely different but strikingly similar locally...

    Monika Sokolowskaet al. Crystal structure of the bba-Me type II restriction endonuclease Hpy99...

    • ...For examples, histidine residues (His-124 in NucA, His-89 in Serratia nuclease, His-103 in colicin E9, His-98 in I-PpoI, and His-80 in Vvn) act as general bases to active water molecules for the nucleophilic attacks on the phosphorus atoms [13-17]...
    • ...Asparagine residues (Asn-155 in NucA, Asn-119 in Serratia nuclease, Asn-119 in I-PpoI, and Asn- 127 in Vvn) bind to the essential magnesium ions, which interact with the 3'-oxygen leaving groups [14,16,21,22]...
    • ...His-141 was also highly conserved among these nucleases (NucA, His-124; Serratia nuclease, His-89; colicin E9, His-103; I-PpoI, His-98) [13-15,17]...
    • ...The active site of the H-N-H endonucleases supplies one or two magnesium ligands as identified by crystal structure analysis: Asn-155 in NucA, Asn-119 in Serratia nuclease, His-102 and His-127 in colicin E9, and Asn-119 in I-PpoI [14,17,21,22]...

    Shih-Lu Wuet al. Mutagenesis identifies the critical amino acid residues of human endon...

    • ...Several nucleases that generate a 30-OH and 50-phosphate during cleavage require an interaction between a metal ion and the 30-bridging atom of the scissile phosphate (22,28)...

    Joseph E. Deweeseet al. Human topoisomerase IIa uses a two-metal-ion mechanism for DNA cleavag...

    • ...The fairly large effect of the metal species on the catalytic activity, positively on G49A activity and negatively on that of all other mutants (Table 3), may suggest that a metal ion is used in positioning and activating a nucleophile rather than just stabilizing a charge (15)...

    Pernilla Lagerbacket al. Amino Acid Residues in the GIY-YIG Endonuclease II of Phage T4 Affecti...

Sort by: