Resolvase

Abdel-Meguid, S. S., Grindley, N. D. F., Templeton, N. S. and Steitz, T. A. (1984). Qeavage of the site-specific recombination protein yS resolvase the smaller of the two fragments binds DNA specifically. Proc. Natl. Acad. Sci. USA 81,2001-2005. 

Once a Holliday intermediate has formed, a host of enzymes—topoisomerases, the RuvAB branch migration protein, a resolvase, other nucleases, DNA polymerase... 

Figure 5-17 Electron micrograph of a six-noded knot made by the Tn3 resolvase which is involved in movement of the Tn3 transposon (Chapter 27) from one location to another within the genome. Putative six-noded knot DNA was isolated by electroelution from an agarose gel. The knots, which are nicked in one strand, were denatured to allow the nicked strand to slide away and leave a ssDNA knot. This was coated with E. coli rec A protein (Fig. 27-24) to greatly thicken the strand and to permit the sign of each node (designated in the tracing) to be seen. From Wasserman et a/.184...

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... 

The resolvase / invertase family and invertible DNA sequences. A second large family of recombinases act by cleaving a target DNA sequence hydrolytically leaving a free 3 -OH end (Eq. 27-14, step a). This free end then attacks a phosphodiester linkage in a second strand of DNA, cleaving that strand with an in-line nucleophilic displacement (step b). Active sites usually contain a characteristic cluster of aspartate and... 

Tlie synaptic complex contains 240 bp of DNA and at least two resolvase dimers. All four DNA chains are cut to give eight ends. Four of these are bound to the serine side chains in phosphodiester linkage. In the second step the freed 3 -OH groups react with the bound ends of the other duplex via a transesterifica-tion reaction to form the recombinant chains. 

The resolvases act on supercoiled cointegrated DNA molecules that contain two directly repeated res sites to produce two singly linked circles (which are still supercoiled) each containing one res site as shown in Fig. 27-32. The two res (resolution) sites within the transposons are aligned, the open circle of DNA shown at the upper left being folded as shown in the lower part of the drawing. The DNA substrate is not knotted. However, after recombination it is catentated and will require action of a topoisomerase to separate... 

The recombination process triggered by the initial scissions made by exoV and mediated by the recA enzyme are not sufficient for recombination between interacting chromosomes. An additional enzyme, resolvase, is required for efficient separation of the recombining chromosomes in the recA-chromosome complex. This protein is encoded by the ruvC gene in E. coli and is absolutely required for homologous recombination in the bacterium. Its effectiveness has also been demonstrated in a cell-free in vitro system. 

Mashal R, Koontz J, Sklar J, Detection of mutations by cleavage of DNA heteroduplexes with bacteriophage resolvases. Nat Genet 1995 9(2) 177-183. 

Merighi, M., Ellermeier, C., Slauch, J., Gunn, J. Resolvase-in vivo expression technology analysis of the Salmonella enterica serovar Typhimurium PhoP and PmrA regulons in BALB/c mice. J Bacteriol 187 (2005) 7407-7416. 

Li W, Kamtekar S, Xiong Y, Sarkis GJ, Grindley ND, Steitz TA. Structure of a synaptic gammadelta resolvase tetramer covalently linked to two cleaved DNAs. Science 2005 309 1210-1215. 

Members of the structurally related superfamily of enzymes that include RNase H, RuvC resolvase, MuA transposase, and retroviral integrase contain at least three acidic residues in the active site and require divalent cations, such as Mg or Mn ", for their enzymatic activity. However, the precise placement of cations is reported in the X-ray crystal structures of only two of these proteins, E. coli RNase H and HIV-1 RNase H. Details of the location of metal ions in the active site of retroviral integrases can enhance our understanding of the catalytic mechanism of these enzymes and their relationship to that of other members of the superfamily. We present the structure of ASV IN catalytic domain with the essential cations Mg or Mn " " bound in the active site. In addition, we present the structure of an inactive complex of the catalytic domain of ASV IN with Zn ". ... 

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. 

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... 

A distinctive feature of the recombination reaction mediated by Tn3 and yS resolvases is the requirement for two res sites present as direct repeats (Reed and Grindley, 1981 Kitts etal., 1983). DNA relaxation by Tn3 resolvase also occurs efficiently only on DNA molecules containing two res sites in a directly repeated orientation (Krasnow and Cozzarelli,... 

The resolvase protein from -yS has been crystallized (Weber et al.,... 

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