The recent developments in cryo-EM have revolutionized our access to previously refractory structures. In particular, such studies of mammalian mitoribosomes have confirmed the absence of any 5S rRNA species and revealed the unexpected presence of a mitochondrially encoded tRNA (mt-tRNA) that usurps this position. Although the cryo-EM structures resolved the conundrum of whether mammalian mitor...

Transfer RNAs (tRNAs) are substrates for complex enzymes, such as aminoacyl-tRNA synthetases and ribosomes, and play an essential role in translation of genetic information into protein sequences. Here we describe a general method for labeling tRNAs with fluorescent dyes, so that the activities and dynamics of the labeled tRNAs can be directly monitored by fluorescence during the ribosomal deco...

The N1 imino units in Escherichia coli tRNAfMet, tRNAGlu, tRNAPhe, and tRNATyr were studied by 1H-15N NMR using three different techniques to suppress signals of protons not attached to 15N. Two of the procedures, Fourier internuclear difference spectroscopy and two-dimensional forbidden echo spectroscopy permitted 1H and 15N chemical shifts to be measured simultaneously at 1H sensitivity. The ...

Three analogs of unmodified yeast tRNAPhe, each possessing a single disulfide cross-link, have been designed and synthesized. One cross-link is between G1 and C72 in the amino acid acceptor stem, a second cross-link is in the central D region of yeast tRNAPhe between C11 and C25 and the third cross-link bridges U16 and C60 at the D loop/T loop interface. Air oxidation to form the cross-links is...

In the presence of Escherichia coli ribosomes and elongation factor EF) Tu, 2'(3')-O-L-phenylalanyladenosine (AdoPhe), the 3'-terminal portion of Phe-tRNAPhe, promotes the hydrolysis of GTP. The reaction requires the presence of both 30S and 50S ribosomal subunits and of proteins L7/L12 on the 50S subunit, is unaffected by mRNA [poly(uridylic acid)], and is strongly stimulated by EF-Ts. It is p...

Anticodon-anticodon pairing of complementary tRNA's has been studied by fluorescence temperature jump measurements in the presence of different ligands as an approach for the evaluation of ligand binding to tRNA. This procedure is particularly useful for ligands which do not show spectroscopic changes upon binding, but affect the pairing potential of anticodons. Addition of phenylalanine-, tyro...

A series of P-site probes, chlorambucilyl-(Pro)n-Phe-tRNAPhe, were prepared and reacted with poly(U)-directed Escherichia coli MRE 600 ribosomes. Upon binding of the probes to ribosomes, 90% of the cpm bound were not released following subsequent interaction with puromycin. In the absence of poly(U) or in the presence of poly(C), binding was limited to the amount of cpm bound if ribosomes were ...

the mitochondrial dna (mtdna) mutations in mitochondrial coding and non coding regions seem to be important in carcinogenesis. the aim of this investigation was to evaluate coding region (mt-trnaphe and trnapro) and non-coding sequence, mitochondrial displacement loop (mtdna d-loop), in the cancerous and non-cancerous lesions of iranian patients with breast cancer (bc). genomic dna was extracte...

The structure of the ribotrinucleoside diphosphate UpUpC, the codon for phenylalanine, bound to yeast tRNAPhe in solution is elucidated using time-dependent proton-proton transferred nuclear Overhauser enhancement measurements to determine distances between bound ligand protons. The glycosidic bond and ribose conformations are low anti and 3'-endo, respectively, typical of an A-RNA type structu...

The ability of rabbit liver ribosomes and their subunits to form complexes with different forms of tRNAPhe (aminoacyl-, peptidyl- and deacylated) was studied using the nitrocellulose membrane filtration technique. The 80 S ribosomes were shown to have two binding sites for aminoacyl- or peptidyl-tRNA and three binding sites for deacylated tRNA. The number of tRNA binding sites on 80 S ribosomes...