Conformational transition of the 30 S ribosomal subunit induced by initiation factor 3 (IF-3)

Paradies, Hasko H.; Franz, Alfred; Pon, Cynthia L.; Gualerzi, Claudio O.

doi:10.1016/s0006-291x(74)80022-7

Cited by 18 publications

(6 citation statements)

References 22 publications

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“…This notion is in line with previous reports about a general effect of IF-3 on the conformation of 30-S subunits [17][18][19]50,51]. The IF-3-induced conformational changes in the 30-S subunit have been found to affect the kinetic parameters of the primary reactions that initiate protein synthesis, and make the 30-S particle more 'accessible' to the relevant ligands (mRNA, tRNA) [20].…”

Section: Discussionsupporting

confidence: 93%

Translation of MS2 RNA in vitro in the Absence of Initiation Factor IF‐3

Zipori

Bosch

Duin

1978

European Journal of Biochemistry

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An Escherichia coli cell‐free translational system, deprived of initiation factor IF‐3, has been used to study the role of the factor in protein synthesis. In this system, 30‐S ribosomal subunits are preincubated together with MS2 phage RNA in a small volume in the presence of 10 mM Mg(Ac)2; the missing components required for protein synthesis are then added and assembly of elongating ribosomes is allowed to occur. This stepwise assembly process prermits formation of functional complexes which can carry out protein synthesis in the complete absence of IF‐3. The translational products, obtained in the absence of IF‐3, have been analysed and shown to be similar to those synthesized in the presence of the factor. The main product observed is the phage coat protein.

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Section: Discussionsupporting

confidence: 93%

Translation of MS2 RNA in vitro in the Absence of Initiation Factor IF‐3

Zipori

Bosch

Duin

1978

European Journal of Biochemistry

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“…The preparation of 30S ribosomal subunits (11), radioactively labeled Phe-tRNA (12), and N-acetylPhe-tRNA (13) were performed as previously described.…”

Section: Methodsmentioning

confidence: 99%

Effect of Initiation Factor 3 Binding on the 30S Ribosomal Subunits of Escherichia coli

Pon

Gualerzi

1974

Proc. Natl. Acad. Sci. U.S.A.

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Under certain conditions, initiation factor 3 (IF-3) can cause the release of aminoacyl-tRNA bound to 30S ribosomal subunits of E. coli. It is shown that this IF-3-induced aminoacyl-tRNA release cannot be attributed to either nucleolytic attack or competition between IF-3 and aminoacyl-tRNA for the same ribosomal binding site.It was found that the 30S-aminoacyl-tRNA-codon complexes formed in the absence of IF-3 are intrinsically different from those prepared in the presence of IF-3. In the absence of IF-3, the ribosomal binding of aminoacyl-tRNA is a virtually irreversible process, since the bound aminoacyl-tRNA can neither be spontaneously released upon dilution nor exchanged for unbound aminoacyl-tRNA. In the presence of IF-3, the binding of one molecule of IF-3 per 30S ribosome renders the binding of aminoacyl-tRNA reversible upon dilution and promotes exchange between bound and unbound aminoacyl-tRNA. It is suggested that this difference is due to a conformational transition of the 30S ribosomal subunit induced by the binding of The possible implications of this finding in relation to the mechanism of action of IF-3 and its functional role in the cell are discussed.

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“…Evidence has been presented that the 30 S particle undergoes a configurational change during association with 50 S subunits [ 18] and the importance of the configuration of the 30 S particles in the binding of IF-3 has already been pointed out [17]. The ability of IF-3 to induce a configurational transition of the 30 S subunits will be described in a forthcoming paper [9].…”

Section: Discussionmentioning

confidence: 99%

“…The preparation of E. coli (MRE 600) 30 S ribosomal subunits will be described in detail in a forthcoming paper [9]. The purification of IF-3 was carried out as previously reported [10].…”

Section: Methodsmentioning

confidence: 99%