Distance between ribosomes on polysome (center of mass to center of mass)

Value 22 nm Range: ±2 nm
Organism Bacteria Escherichia coli
Reference Brandt F, Etchells SA, Ortiz JO, Elcock AH, Hartl FU, Baumeister W. The native 3D organization of bacterial polysomes. Cell. 2009 Jan 23 136(2):261-71. p.264 right column top paragraphPubMed ID19167328
Method Researchers employed cryoelectron tomography and a template-matching approach to map 70S ribosomes in vitrified bacterial translation extracts and in lysates of active E. coli spheroplasts. The spatial orientation of ribosomes in polysomes was determined by 3D template matching with a resolution-adjusted density derived from a 70S ribosome reference structure (Schuwirth et al., 2005). Particle coordinates and orientations in relation to the reference (Figure S3) were extracted from peaks in the resulting 3D crosscorrelation function (see Experimental Procedures).
Comments Distance vectors from the center of mass of each identified polysomal ribosome to the center of mass of its closest neighbor particle clearly indicated preferential positioning at a distance around 22±2 nm. Researchers' analysis reveals a remarkably well defined arrangement of ribosomes in staggered or helical orientations, with the mRNA being sequestered on the inside, while the tRNA entrance sites and the polypeptide exit sites are exposed to the cytosol. See BNID 105001. Note-Martin and Miller 1983, PMID 6683685 p. 345 right column 2nd paragraph write that a ribosome binds every ~135 nts in sea urchin polysome
Entered by Uri M
ID 105000