title: The Rad27 (Fen-1) nuclease inhibits Ty1 mobility in Saccharomyces cerevisiae.
abstract: Although most Ty1 elements in Saccharomyces cerevisiae are competent for retrotransposition, host defense genes can inhibit different steps of the Ty1 life cycle. Here, we demonstrate that Rad27, a structure-specific nuclease that plays an important role in DNA replication and genome stability, inhibits Ty1 at a post-translational level. We have examined the effects of various rad27 mutations on Ty1 element retrotransposition and cDNA recombination, termed Ty1 mobility. The point mutations rad27-G67S, rad27-G240D, and rad27-E158D that cause defects in certain enzymatic activities in vitro result in variable increases in Ty1 mobility, ranging from 4- to 22-fold. The C-terminal frameshift mutation rad27-324 confers the maximum increase in Ty1 mobility (198-fold), unincorporated cDNA, and insertion at preferred target sites. The null mutation differs from the other rad27 alleles by increasing the frequency of multimeric Ty1 insertions and cDNA recombination with a genomic element. The rad27 mutants do not markedly alter the levels of Ty1 RNA or the TyA1-gag protein. However, there is an increase in the stability of unincorporated Ty1 cDNA in rad27-324 and the null mutant. Our results suggest that Rad27 inhibits Ty1 mobility by destabilizing unincorporated Ty1 cDNA and preventing the formation of Ty1 multimers.
authors.affiliation: Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, Maryland 21702, USA.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Sundararajan
authors.forename: Bum-Soo
authors.initials: BS
authors.lastname: Lee
authors.forename: David J
authors.initials: DJ
authors.lastname: Garfinkel
mesh_terms: D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D045585:Flap Endonucleases; D009154:Mutation; D011995:Recombination, Genetic; D018626:Retroelements; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D018626:Retroelements; D029701:Saccharomyces cerevisiae Proteins; D004706:Endodeoxyribonucleases; D045585:Flap Endonucleases; C468323:RAD27 protein, S cerevisiae