We recently showed that RNase III can process a small stable RNA, precursor 10Sa RNA, that accumulates in an rne (RNase E) strain at non-permissive temperatures. Precursor 10Sa (p10Sa) RNA is processed to 10Sa RNA in two steps, the first step is catalyzed by RNase III in the presence of @entity3281 but not @entity1025 . It was shown that RNase III cosediments with membrane preparation from wild type as well as RNase III overexpressing cells. However, the possibility of membrane preparation contamination with ribosomes could not be ruled out. Here we show that RNase III, E and P are not associated with ribosomes. @entity526 cells were opened either by @entity5383 grinding or by sonication and fractionated into cytosolic and pellet fractions. The characterization of membrane preparations was done by assaying @entity2125 oxidase, a bona fide membrane enzyme. Ribosomes prepared by @entity5383 grinding were found to be contaminated with small fragments of membrane which contained RNase III activity. RNase III and @entity2125 oxidase activities were present in the ribosomal preparations which could be solubilized by reagents that dissolve the inner membrane. Isopycnic @entity969 gradient centrifugation of the membrane and ribosomal preparations also confirmed that RNase III fractionated with the inner membrane. Similarly RNase P activity was found in the corresponding fractions when isopycnic centrifugation of membrane and ribosome preparations was carried out. RNase E activity was also found to be present mostly in the post-ribosomal supernatant. These findings show that RNase III, E and P are not ribosomal enzymes.

RNA processing enzymes RNase III, E and P in XXXX are not ribosomal enzymes.

@entity2125 :: ('MESH:D009243', 'Chemical') :: ['NADH'] @entity1025 :: ('CHEBI:18420', 'Chemical') :: ['Mg2+'] @entity3281 :: ('CHEBI:29035', 'Chemical') :: ['Mn2+'] @entity969 :: ('MESH:D013395', 'Chemical') :: ['sucrose'] @entity526 :: ('562', 'Species') :: ['E. coli'] @entity5383 :: ('MESH:D000537', 'Chemical') :: ['alumina']
@entity526 :: (562,Species) :: ['Escherichia coli']
