Release of ribosomal proteins from Escherichia coli ribosomes with high concentrations of lithium chloride.

Abstract

Abstract The sequential release of ribosomal proteins from Escherichia coli ribosomes under the influence of concentrated LiCl solutions was studied. Treatment of 50 s or 30 s ribosomal subunits with various concentrations of LiCl containing 2.5 × 10 −2 m -Tris buffer (pH 7.8) and 10 −1 m -magnesium acetate or 5 × 10 −3 m -EDTA produced a series of protein-deficient particles having sedimentation coefficients of 40, 36, 28 and 25 s (from a 50 s subunit), and of 25, 23, 21, 19 and 16 s (from a 30 s subunit). The protein components of these particles have been analysed by carboxymethyl-cellulose column chromatography. It was shown that release of protein from ribosomes does not occur in a random fashion but follows a certain definite order. Furthermore, this release proceeds in more or less discrete steps as already pointed out by Lerman, Spirin, Gavrilova & Golov (1966). Ribonucleoprotein particles having a single (or two) protein component are obtained by exposing the 30 or 50 s ribosome subunits to 3.5 m -LiCl in the absence of magnesium ions for 82 hours.