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RusA proteins from the extreme thermophile Aquifex aeolicus and lactococcal phage r1t resolve Holliday junctions

Sharples, G.J.; Bolt, E.L.; Lloyd, R.G.

Authors

E.L. Bolt

R.G. Lloyd



Abstract

The RusA protein of Escherichia coli is a DNA structure-specific endonuclease that resolves Holliday junction intermediates formed during DNA replication, recombination and repair by introducing symmetrically paired incisions 5' to CC dinucleotides. It is encoded by the defective prophage DLP12, which raises the possibility that it may be of bacteriophage origin. We show that rusA-like sequences are indeed often associated with prophage sequences in the genomes of several bacterial species. They are also found in many bacteriophages, including Lactococcus lactis phage r1t. However, rusA is also present in the chromosome of the hyperthermophilic bacterium Aquifex aeolicus. In this case, there is no obvious association of rusA with prophage-like sequences. Given the ancient lineage of Aquifex aeolicus, this observation provides the first indication that RusA may be of bacterial origin. The RusA proteins of A. aeolicus and bacteriophage r1t were purified and shown to resolve Holliday junctions. The r1t enzyme also promotes DNA repair in strains lacking the RuvABC resolvase. Both enzymes cleave junctions in a sequence-dependent manner, but the A. aeolicus RusA shows a different sequence preference (3' to TG) from the E. coli protein (5' to CC), and the r1t RusA has relaxed sequence dependence, requiring only a single cytosine.

Citation

Sharples, G., Bolt, E., & Lloyd, R. (2002). RusA proteins from the extreme thermophile Aquifex aeolicus and lactococcal phage r1t resolve Holliday junctions. Molecular Microbiology, 44(2), 549-559. https://doi.org/10.1046/j.1365-2958.2002.02916.x

Journal Article Type Article
Publication Date Apr 1, 2002
Deposit Date May 18, 2007
Journal Molecular Microbiology
Print ISSN 0950-382X
Electronic ISSN 1365-2958
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 44
Issue 2
Pages 549-559
DOI https://doi.org/10.1046/j.1365-2958.2002.02916.x