Arudchandran, A. et al. The absence of ribonuclease H1 or H2 alters the sensitivity of Saccharomyces cerevisiae to hydroxyurea, caffeine and ethyl methanesulphonate: implications for roles of RNases H in DNA replication and repair. Genes Cells 5, 789-802
Arudchandran, Arulvathani;
Cerritelli, Susana;
Narimatsu, Scott;
Itaya, Mitsuhiro;
Shin, Deug-Yong;
Shimada, Yuji;
Crouch, Robert J.
Background: RNA of RNA-DNA hybrids can be
degraded by ribonucleases H present in all organisms
including the eukaryote Saccharomyces cerevisiae.
Determination of the number and roles of the
RNases H in eukaryotes is quite feasible in S.
cerevisiae.
Results: Two S. cerevisiae RNases H, related to
Escherichia coli RNase HI and HII, are not required
for growth under normal conditions, yet, compared
with wild-type cells, a double-deletion strain has an
increased sensitivity to hydroxyurea (HU) and is
hypersensitive to caffeine and ethyl methanesulphonate
(EMS). In the absence of RNase H1, RNase H2
activity increases, and cells are sensitive to EMS but
not HU and are more tolerant of caffeine; the latter
requires RNase H2 activity. Cells missing only
RNase H2 exhibit increased sensitive to HU and
EMS but not caffeine
Conclusions: Mutant phenotypes infer that some
RNA-DNA hybrids are recognized by both
RNases H1 and H2, while other hybrids appear to
be recognized only by RNase H2. Undegraded
RNA-DNA hybrids have an effect when DNA
synthesis is impaired, DNA damage occurs or the
cell cycle is perturbed by exposure to caffeine
suggesting a role in DNA replication/repair that
can be either bene®cial or detrimental to cell
viability.