J. Biol. Chem., Vol. 255, Issue 24, 11704-11709, 12, 1980
RNA-dependent ATPase from Saccharomyces cerevisiae
O Belhadj, A Sentenac and P Fromageot
A new RNA-dependent ATPase has been isolated from yeast chromatin extracts
and partially characterized. The protein has a sedimentation coefficient of
about 7 S. The enzyme hydrolyzes specifically ATP (or dATP) to ADP (or
dADP) and Pi in the presence of Mg2+ or Mn2+ ions and requires a
single-stranded polynucleotide as cofactor. The order of efficiency of
synthetic polymers is poly(rU) > poly(rI) greater than or equal to
poly(dU) > poly(rA) greater than or equal to poly(rC). Among natural
polymers, single-stranded DNA and poly(rA)-containing mRNA from yeast are
also active but less so than poly(rU). The enzyme exhibits a pH optimum of
8 and is fully inhibited by 0.25 M NaCl. The Km for ATP is0.2 mM. The
resemblance between this ATPase and DNA-dependent ATPases from other
sources, as well as the termination factor rho, is discussed.