Holliday junction resolvases

Yet another superfamily, the nucleotidyl-transferase family, also utilises the two-metal-ion-dependent catalysis the members include transposases, retrovirus integrases, and Holliday junction resolvases. Whereas, in the nucleases, the Mg + ions are asymmetrically coordinated, and play distinct roles, in respectively activating the... 

An important characteristic of Holliday junctions formed from homologous duplexes is that they can move by a process called branch migration.295 Because of the twofold symmetry of the branched structure the hydrogen bonds of one base pair can be broken while those of a new base pair are formed, the branch moving as shown in Fig. 5-28. Notice that, in this example, the nonhomo-logous (boxed) base pairs TA and GC have become mispaired as TG and AC after branch migration. More significantly, the junction may be cut by a resolvase at the points marked... 

RuvC is an endonuclease that is highly specific for Holliday junctions. It is a resolvase that cuts at either points a,a or b,b of Eq. 27-11 to form either "patched" or "spliced" recombinant DNA (Fig. 27-26C). Similar resolvases process bacteriophage DNA562-564 and have also been found in yeasts and in mammals.565 566 All are dimeric metal ion-dependent proteins.567... 

Ariyoshi, M., Vassylyev, D. G., Iwasaki, H., Nakamura, H., Shinagawa, H., and Morikawa, K. (1994). Atomic structure of the RuvC resolvase A Holliday junction-specific endonuclease ffom . coli. CellJS, 1063-1072. 

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