Linked Life Data

6361027

Source:http://linkedlifedata.com/resource/pubmed/id/6361027

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
1984-2-14
pubmed:abstractText
In a classical translocation experiment, deacylated RNA is bound to the ribosomal peptidyl-tRNA site (P site) and N-acetyl-phenylalanyl-tRNA (AcPhe-tRNA) to the aminoacyl-tRNA site (A site); upon addition of elongation factor (EF-G) and GTP, AcPhe-tRNA is translocated from the A to the P site. Here, we demonstrate a model reaction for a spontaneous, EF-G independent translocation. If AcPhe-tRNA is bound to the P site and Phe-tRNA to the A site at 15 mM Mg2+, then at 37 degrees C up to 60% of the AcPhe2-tRNA formed is found at the P site without the addition of EF-G. We demonstrate the following: 1) the spontaneous translocation is not merely illusory as a result of Phe-tRNA binding directly to the P site; 2) it is not mimicked by release of AcPhe2-tRNA from an A site and rebinding to a P site of another ribosome; 3) it is not caused by an EF-G contaminant present in the 70 S preparation, since without EF-G the spontaneous translocation works equally well in the presence of guanyl-5'-yl imidodiphosphate or fusidic acid; 4) AcPhe2-tRNA evidently has a higher affinity for the P site than AcPhe-tRNA, thus promoting the spontaneous translocation; and 5) peptide-bond formation favors the subsequent translocation. Addition of EF-G increases the initial rate by a factor of 13. Furthermore, at 15 mM Mg2+, 37 degrees C and in the presence of EF-G and GTP, Phe-tRNA cannot be translocated from the A to the P site, if the P site is occupied by deacylated tRNA. With the spontaneous translocation system, all reactions of the elongation cycle are cooperatively interconnected; i.e. upon binding of aminoacyl-tRNA to the A site, a significant portion of the ribosomes performs a complete round of the elongation cycle without the addition of elongation factor EF-G.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
258
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
15105-13
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Spontaneous, elongation factor G independent translocation of Escherichia coli ribosomes.
pubmed:publicationType
Journal Article