| Value |
7
nm
Range: ±1 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.266 right column 2nd 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). The distance between codon recognition
sites in densely packed neighboring
ribosomes was estimated as follows. Positions of 26 nucleotides
resolved in a 70S ribosomal crystal structure containing mRNA
(Yusupova et al., 2006) were used in the polysomal model for
each ribosome. Between two adjacent ribosomes, an average
distance of 7 ± 1 nm was determined from the exit site of the
mRNA of one ribosome to the entrance site of the next ribosome. |
| Comments |
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. For the transcripts Luc 197, 371, and 550, (numbers of amino acids, multiply by 3 to receive nucleotide number) the average numbers of ribosomes within putative polysomes were 4±1, 8±2, and 11±2, respectively. These transcripts were constructed in vitro. For number of ribosomes in polysome in vivo see BNID 105207, 102024. See BNID 105000. Note-a measured value of 7.35nm given in supporting online material p.6 |
| Entered by |
Uri M |
| ID |
105001 |