“Compartmentalization” of Escherichia coli Ribosomes and Ribonucleic Acid

Abstract

Escherichia coli spheroplasts lysed by Brij 58 and deoxycholate were separated into supernatant (S) and membrane fractions by low-speed centrifugation. The membrane fraction was further divided into that which was releasable by deoxyribonuclease (fraction D) and that which was not (M). In the presence of 10-2 M Mg2+, the S, D, and M fractions contained, respectively, 60, 20, and 20% of the total cellular ribonucleic acid (RNA). Ribosomal and transfer RNA (rRNA, tRNA) were found in each fraction. The M + D fraction RNA was labeled more by a pulse label. Incorporation of uracil into the D fraction continued only as long as the uptake of exogenous uracil, suggesting that this was a major primary site of RNA synthesis. From pulse-labeled cells, each fraction contained precursor rRNA, and there was a 10S RNA in the M fraction. Ninety per cent of the ribosomal subunits and the ribosomal precursor particles, 26 and 43S, were in the S fraction. Precursor RNA (17S) was found in the 26S precursor particles. The D fraction contained 38% of the polysomes (this does not consider polysomes, if any, of the M fraction) which were labeled four times as much as the supernatant polysomes by a 1-min pulse of uracil. These results are interpreted to mean that new RNA is associated with a cytoplasmic membrane-RNA polymerase-DNA complex.

Interaction of cytoplasmic membrane and ribosomes in Escherichia coli: spectinomycin-induced disappearance of membrane protein I-19

“…It is highly probable, therefore, that the Sucd Spcr mutation and spectinomycin cause some alteration in a certain part of ribosomes that is important for interaction with the cytoplasmic membrane. Although several workers have studied the role of ribosomes in the membrane fraction of bacteria (4,5,13,15,16), structural and functional relationships between ribosomes and the cytoplasmic membrane have not been well established. Two independent results discussed here (10; this paper) can be best interpreted by the existence of structural interaction between ribosomes and the cytoplasmic membrane.…”

Structure and function of the cell envelope of gram-negative bacteria.

“…The location of protein synthesis in the prokaryotic cell has not yet been established, but many workers (48,177,202) have suggested that this process is concentrated at the inner aspect of the cytoplasmic membrane. This would appear to be opposed to the evidence of Miller's group (131,132) which indicates that polyribosomes form on nascent messenger ribonucleic acid and that protein synthesis, therefore, occurs in immediate association with the chromatin of the cell.…”

Coordinated alterations in ribosomes and cytoplasmic membrane in sucrose-dependent, spectinomycin-resistant mutants of Escherichia coli

“…But evidence has also accumulated in support of the view that these separate functions are interrelated. For example, the structural interaction between cytoplasmic membrane and ribosomes (4,18,20,21) and a specific function of the ribosomes bound to cytoplasmic membrane (3) have been reported. In higher organisms, the existence of ribosomes bound to endoplasmic reticulum and their specific role in the formation of particular proteins have been well established (7,16,17).…”