Search PubMed⌕ Search

Biomedical subjects

R A Garrett

Publications and source records attributed to R A Garrett.

At least 109 records · Page 6Linked to original sources
PubMed1979

Studies on the binding of the ribosomal protein complex L7/12-L10 and protein L11 to the 5'-one third of 23S RNA: a functional centre of the 50S subunit.

The RNA binding sites of the protein complex of L7/12 dimers and L10, and of protein L11, occur within the 5'-one third of 23S RNA. Binding of the L7/12-L10 protein complex to the 23S RNA is stimulated by protein L11 and vice-versa. This is the second example to be established of mutual stimulation of RNA binding by two ribosomal proteins or protein complexes, and suggests that this may be an important principle governing ribosomal protein-RNA assembly. When the L7/12-L10 complex is bound to the RNA, L10 becomes strongly resistant to trypsin. Since the L7/12 dimer does not bind specifically to the 23S RNA, this suggests that L10 constitutes a major RNA binding site of the protein complex. Only one of the L7/12 dimers is bound strongly in the (L7/12-L10)-23S RNA complex; the other can dissociate with no concurrent loss of L10.

Escherichia coli↗
PubMed1979

A ribonuclease-resistant region of 5S RNA and its relation to the RNA binding sites of proteins L18 and L25.

An RNA fragment, constituting three subfragments of nucleotide sequences 1-11, 69-87 and 89-120, is the most ribonuclease-resistant part of the native 5S RNA of Escherichia coli, at 0 degrees C. A smaller fragment of nucleotide sequence 69-87 and 90-110 is ribonuclease-resistant at 25 degrees. Degradation of the L25-5S RNA complex with ribonuclease A or T2 yielded RNA fragments similar to those of the free 5S RNA at 0 degrees C and 25 degrees C; moreover L25 remained strongly bound to both RNA fragments and also produced some opening of the RNA structure in at least two positions. Protein L18 initially protected most of the 5S RNA against ribonuclease digestion, at 0 degrees C, but was then gradually released prior to the formation of the larger RNA fragment. It cannot be concluded, therefore, as it was earlier (Gray et al., 1973), that this RNA fragment contains the primary binding site of L18.

Base Sequence↗
PubMed1979

The structure of the RNA binding site of ribosomal proteins S8 and S15.

Proteins S8 and S15 from the 30 S ribosomal subunit of Escherichia coli were bound to 16 S RNA and digested with ribonuclease A. A ribonucleoprotein complex was isolated which contained the two proteins and three noncontiguous RNA subfragments totaling 93 nucleotides, that could be unambiguously located in the 16 S RNA sequence. We present a secondary structural model for the RNA moiety of the binding site complex, in which the two smaller fragments are extensively base-paired, respectively, to the two halves of the large fragment, to form two disconnected duplexes. Each of the two duplexes is interrupted by a small internal loop. This model is supported by (i) minimum energy considerations, (ii) sites of cleavage by ribonuclease A, and (iii) modification by the single strand-specific reagent kethoxal. The effect of protein binding on the topography of the complex is reflected in the kethoxal reactivity of the RNA moiety. In the absence of the proteins, 5 guanines are modified; 4 of these, at positions 663, 732, 733, and 741, are strongly protected from kethoxal when protein S15 is bound.

Base Sequence↗
PubMed1979

Chemical evidence for a codon-induced allosteric change in tRNALys involving the 7-methylguanosine residue 46.

[32P]TRNALys, from Escherichia coli, was modified with kethoxal, in the presence and absence of the oligonucleotide codon (A)4. The presence of the codon resulted in a faster modification rate of the tRNA at three guanine sites which were identified by a diagonal fingerprint method. A large increase in the modification rate occurred at the 7-methylguanosine residue 46 (m7G-46) in the presence of the codon: weakly enhanced modification was observed at G-15 and G-57. It is concluded that the formation of a codon-anticodon complex induces, primarily, a conformational change involving disruption of the m7G-46 from the m7G-46 . G-22 . C-13 base triple. Subsequently, the guanines of G-15 and G-57, in the D and T loops, respectively, become slightly more reactive, suggesting a weak tendency for these two interacting arms to unfold. The results are interpreted in terms of an equilibrium between two main conformers, and a third minor one; the possible significance of these conformers in protein biosynthesis, is considered.

Base Sequence↗
PubMed1978

Bilateral Wilms tumors.

The current management of bilateral Wilms tumor is reviewed and the high incidence of concurrent anomalies with bilateral Wilms tumor is demonstrated in 4 of 5 children. Standardization of management has not been established. Of the 5 patients 3 survived 30 months to 11 years without recurrent tumor. Two had unilateral nephrectomy and partial nephrectomy, while 1 had bilateral nephrectomy and allotransplant. All survivors have had adjunctive chemotherapy and radiotherapy.

Female↗
PubMed1978

RNA-RNA interactions in the binding site of protein L24 on 23S ribosomal RNA of Escherichia coli: 1. Evidence for their occurrence between widely separated sequence regions.

Protein L24, from the Escherichia coli ribosome, protects a large region of 23S RNA against ribonuclease digestion. This protected RNA consists of a series of non-contiguous subfragments encompassing about 480 nucleotides at the 5' -end of 23S RNA (1). The present work demonstrates that this RNA moiety remains intact, after removal of protein L24, indicating that the subfragments are maintained together by RNA-RNA interactions. Using a urea washing procedure, the weakly bound RNA subfragments were selectively removed leaving more strongly interacting subfragments that were identified, by gel electrophoresis and oligonucleotide fingerprinting, and shown to derive from widely separated sequence regions.

Base Sequence↗
PubMed1978

Small-angle X-ray titration of the complex formed between the ribosomal protein S4 and its 16S binding site, S4-RNA: a central core in the 30S subunit.

X-ray scattering titrations at 21 degree C and in ribosomal reconstitution buffer indicate that the S4-RNA and the protein S4 from a 1:1 complex with a stability constant, log K approximately 6.5. When the complex forms, there is only a limited change in the scattering curve indicating that S4-RNA essentially retains its conformation during the complex formation. The increase in the gyration radius as a result of the complex formation, delta R = 4 +/- 3 A, as well as the experimental scattering curve of the complex can be explained by models where the protein S4 is supposed to interact with the periphery of the S4-RNA.

Binding Sites↗
PubMed1978

A new RNA-RNA crosslinking reagent and its application to ribosomal 5S RNA.

The synthesis of a new RNA specific bifunctional crosslinking reagent, 1.4-phenyl-diglyoxal, is described which reacts exclusively with guanosines. The properties of the crosslinked products enabled us to develop a straightforward method for identifying the reacted nucleotides. Results obtained with ribosomal 5S RNA of Escherichia coli demonstrate the formation of an intramolecular crosslink between guanosine-2 and guanosine-112 in the stem region.

Aldehydes↗
PubMed1977

Small-angle X-ray titration study on the complex formation between 5-S RNA and the L18 protein of the Escherichia coli 50-S ribosome particle.

The 5-S RNA (A) and the L18 protein (B) from Escherichia coli ribosomes form one single AB complex in the concentration ranges supposed to prevail in vivo; at concentrations of L18 higher than 40 mM there is some indication for a minor species, most probably an AB2 species. This is indicated from the X-ray scattering titration data of the 5-S RNA/L18 system recorded at 21 degrees C in ribosomal reconstitution buffer. As a result of the 1:1 complex formation, there is a relatively small but defined increase in the radius of gyration from 3.61 to 3.85 nm. This result as well as the experimental scattering curve can be explained by models where it is assumed that the elongated L18 model is quite far from the electron density centre and where protein L18 interacts with one or both of the minor arms of the supposed Y-shaped 5-S RNA molecule.

Escherichia coli↗