Stability of ribosomes of Staphylococcus aureus S6 sublethally heated in different buffers.
Cells of Staphylococcus aureus heated at 52 degrees C in magnesium-chelating buffers [pH 7.2, 50 mM potassium phosphate or 50 mM tris(hydroxymethyl)-aminomethane containing 1 mM ethylenediaminetetraacetic acid] leaked 260-nm absorbing material, shown to be RNA, and suffered destruction of their ribosomes. These cells did not regain their salt tolerance when repair was carried out in the presence of actinomycin D (5 microgram/ml). Cells similarly heated in magnesium-conserving buffers [pH 7.2, 50 mM tris(hydroxymethyl)aminomethane containing 10 mM MgCl2 or piperazine buffer] did not leak RNA, suffered no ribosomal damage when heated for 15 min, and recovered, at least partially, in the presence of actinomycin D. Ribosomal damage, is therefore, a consequence of Mg2+ loss and is not an effect of heat per se. Cells suspended in either Mg2+-chelating or Mg2+-conserving buffers lost salt tolerance to about the same extent during heating at 52 degrees C. Therefore, sublethal heat injury can not be attributed to ribosomal damage.
D002021:Buffers; D002499:Centrifugation, Density Gradient; D003609:Dactinomycin / Q000494:pharmacology; D006358:Hot Temperature; D008274:Magnesium / Q000494:pharmacology; D012335:RNA, Ribosomal / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000648:ultrastructure*
D002021:Buffers; D012335:RNA, Ribosomal; D003609:Dactinomycin; D008274:Magnesium