Architecture of the Escherichia coli ribosome as determined by immune electron microscopy.

Abstract

Binding sites for antibodies specific to nineteen of the twenty-one ribosomal proteins from the 30S subunit of E. coli ribosomes have been localized on the surface of the 30S ribosomal subunit by immune electron microscopy. The locations of 13 ribosomal proteins from the 50S subunit were similarily assessed. The arrangement of these proteins is illustrated in three-dimensional models of the 30S and 50S ribosomal subunits and of 70S ribosomes.With specific antibodies to six proteins of the 30S subunit we found only one attachment point for each protein. Antibodies against each of nine of the proteins attached at two separate sites that were separated by various distances. Four further proteins were exposed at three or four sites for antibody binding. Altogether eight to ten of the 19 proteins of the 30S subunit have shown antibody attachment sites at remote points on the surface of the ribosome, at distances which are incompatible with globular shapes; these proteins must therefore have elongated or fibrous structures within the ribosome. On the other hand, only two proteins of the 50S subunit, namely Lii and L18, have so far revealed two separated antibody binding sites; proteins L7/L12 occurred, however, at multiple sites.The 30S ribosomal subunit of Escherichia coli is comprised of 21 ribosomal proteins and one 16S rRNA molecule. Substantial information about the primary structure of these components has accumulated during the last several years (reviewed in refs. 1 and 2). Similarily a good deal is known about the contribution of the various components to the function of the ribosome (reviewed in refs. 3-5). Although several approaches have already contributed to the knowledge of the relative topography of ribosomal components, information regarding the absolute location of the ribosomal proteins has only recently emerged, from electron microscopy of antibody-labeled 30S and 50S subunits (5-10). By means of immune electron microscopy, proteins S4, S5, S13, and S14 were mapped on the surface of the 30S subunit (7,9,10), and preliminary data on the location of proteins S6, Sil, S12, and S19 have also been reported (10).In this paper we present a summary of our data on the location of 19 of the 21 proteins from the 30S subunit in the three-dimensional structure of both the 30S and 70S ribosome. The location of 13 proteins on the 50S ribosomal subunit is given schematically. A detailed documentation and a critique of the results will be published elsewhere*.MATERIALS AND METHODS Preparation of ribosomes and ribosomal subunits from E.

Physical Studies on the Conformation of Ribosomal Protein S4 from Escherichia coli

“…The visualisation by electron microscopy of antibody markers bound to this protein on the ribosome indicates that the protein Abbreviations. PMR, proton magnetic resonance; CD, circular dichroism.is probably very asymmetric [7,8]. Compatible with this result is a frictional coefficient of 1.6, determined by gel filtration and sedimentation 191.…”

“…is probably very asymmetric [7,8]. Compatible with this result is a frictional coefficient of 1.6, determined by gel filtration and sedimentation 191.…”

Small‐angle X‐ray scattering study of the 5S RNA binding proteins L18 and L25 from Escherichia coli ribosomes

“…Similar conclusions have recently been drawn for some other ribosomal proteins. Electron microscope studies using antibody markers [18,19] show proteins $4, $5, S11, S12 as well as $2, $7, S15, and S18 to be elongated, and neutron scattering studies indicate protein $2 to be…”

A ribonuclease-resistant region of 5S RNA and its relation to the RNA binding sites of proteins L18 and L25

“…Its presence in the subunit is essential for ribosomal function (8,9), and it is situated near the interface region which is generally considered to be the main functional centre of the ribosome (10).…”