title: Distance measurement by energy transfer: the 3' end of 16-S RNA and proteins S4 and S17 of the ribosome of Escherichia coli.
abstract: Escherichia coli ribosomal proteins S4 and S17 were specifically labelled at their thiol groups with the acetylaminoethyl-dansyl and/or bimane fluorophores. Each formed a complex with 16-S RNA and, when the other 30-S ribosomal proteins were added, a complete 30-S subunit with at least partial activity. If the 3' end of the RNA was also labelled (with fluorescein) then the distance between the two fluorophores could be measured by Förster-type energy transfer. The result for S4 was 6.0 nm (60 A) in the ribonucleoprotein complex and 5.6 nm (56 A) in the 30-S subunit, and for S17 6.3 nm (63 A) in the complex and 6.2 nm (62 A) in the subunit. There is no evidence for a major change in the relative disposition of the 3' and 5' ends of the 16-S RNA during formation of the 30-S subunit. Sources of error are discussed, including the question of multiple labelling. In order to measure more accurately the extent of energy transfer a procedure based upon enzymic digestion was developed and is detailed in this paper.
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification; D055598:Chemical Phenomena; D002621:Chemistry; D004735:Energy Transfer; D004926:Escherichia coli / Q000378:metabolism*; D011485:Protein Binding; D012329:RNA, Bacterial / Q000302:isolation & purification*; D012335:RNA, Ribosomal / Q000302:isolation & purification*; D012269:Ribosomal Proteins / Q000302:isolation & purification*
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; C037084:ribosomal protein S17; C031798:ribosomal protein S4