Cordycepin-hypersensitive growth links elevated polyphosphate levels to inhibition of poly(A) polymerase in Saccharomyces cerevisiae
Data(s) |
01/01/2008
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Resumo |
To identify genes involved in poly(A) metabolism, we screened the yeast gene deletion collection for growth defects in the presence of cordycepin (3′-deoxyadenosine), a precursor to the RNA chain terminating ATP analog cordycepin triphosphate. <i>Δpho80</i> and <i>Δpho85</i> strains, which have a constitutively active phosphate-response pathway, were identified as cordycepin hypersensitive. We show that inorganic polyphosphate (poly P) accumulated in these strains and that poly P is a potent inhibitor of poly(A) polymerase activity <i>in vitro</i>. Binding analyses of poly P and yeast Pap1p revealed an interaction with a k<sub>D</sub> in the low nanomolar range. Poly P also bound mammalian poly(A) polymerase, however, with a 10-fold higher k<sub>D</sub> compared to yeast Pap1p. Genetic tests with double mutants of <i>Δpho80</i> and other genes involved in phosphate homeostasis and poly P accumulation suggest that poly P contributed to cordycepin hypersensitivity. Synergistic inhibition of mRNA synthesis through poly P-mediated inhibition of Pap1p and through cordycepin-mediated RNA chain termination may thus account for hypersensitive growth of <i>Δpho80</i> and <i>Δpho85</i> strains in the presence of the chain terminator. Consistent with this, a mutation in the 3′-end formation component <i>rna14</i> was synthetic lethal in combination with <i>Δpho80</i>. Based on these observations, we suggest that binding of poly P to poly(A) polymerase negatively regulates its activity. <br /> |
Identificador | |
Idioma(s) |
eng |
Publicador |
Oxford University Press |
Relação |
http://dro.deakin.edu.au/eserv/DU:30039322/holbein-cordycepinhypersensitive-2008.pdf http://dx.doi.org/10.1093/nar/gkm990 |
Direitos |
2007, Oxford University Press |
Tipo |
Journal Article |