PubMed Health⌕ Search

Biomedical subjects

C Ehresmann

Publications and source records attributed to C Ehresmann.

At least 163 records · Page 9Linked to original sources
PubMed1975

An investigation of the 16-S RNA binding sites of ribosomal proteins S4, S8, S15, and S20 FROM Escherichia coli.

The RNA binding sites of four 30-S ribosomal subunit proteins from Escherichia coli, namely S4, S8, S15, and S20 were prepared from reconstituted single protein - 16-S-RNA complexes by mild enzymic digestion of non-protected RNA regions. Oligonucleotide fingerprints of the protected RNA regions were obtained and their positions were located within the 16-S-RNA sequence. They were not completely contiguous regions of RNA; oligonucleotides had been excised from each of them. The binding sites of S4 and S20, and those of S8 and S15 showed overlapping. The specificity of the RNA binding sites was confirmed by a reconstitution method.

Bacterial Proteins↗
PubMed1975

The determination of the primary structure of the 16S ribosomal RNA of Escherichia coli. III. Further studies.

In this paper, we describe in detail the recent progress in the nucleotide sequence analysis of the 16S ribosomal RNA from E. coli. The sequence which has been partially or completely determined so far encompasses 1520 nucleotides, i.e. about 95 percent of the molecule. Possible features of the secondary structure are suggested on the basis of the nucleotide sequence and data on sequence heterogeneities, repetitions and the location of modified nucleotides are presented.

Alkaline Phosphatase↗
PubMed1975

Comparative study of the 16S RNA's of Escherichia coli and Proteus vulgaris.

We have studied the primary structure of 16S ribosomal RNA from Proteus vulgaris. The oligonucleotides containing methylated bases appeared to be the same as those of Escherichia coli, with one exception. We have also studied the base composition of the oligonucleotides obtained after T1 ribonuclease digestion of 16S RNA. On the basis both of their position on the fingerprint and of their pancreatic ribonuclease analyses, approximately 25 appeared to differ from those found in the E. coli T1 fingerprints. From the isolation of large fragments arising from the action of endogeneous endonucleases, we have concluded that the RNA sequences of both species are very similar. We have shown that the 5' and 3' extremities of 16S RNA are mostly conserved. It appears that the regions which are known to interact with ribosomal proteins in E. coli (particularly S8 and S15) are also less modified. It is noteworthy that the sequence modifications which have been observed are clustered and often correspond to regions of heterogeneity in E. coli 16S RNA.

Alkaline Phosphatase↗
PubMed1975

Evidence for tertiary structural RNA-RNA interactions within the protein S4 binding site at the 5'-end of 16S ribosomal RNA of Escherichia coli.+.

Evidence is presented for tertiary structural interaction(s) (interactions(s) between two regions of an RNA molecule that are widely separated in the RNA sequence) within the 5'-one third of the 16S ribosomal RNA of Escherichia coli that constitutes the binding site of protein S4. The two main interacting RNA regions were separated by about 120 nucleotides (sections Q to M) of the 16S RNA sequence. A second, smaller gap, of 13 nucleotides, occurred within section C". The two main interacting regions contain about 150 nucleotides (sections H" to Q) and 160 nucleotides (sections M to C"). They are folded back on one another and, especially in the presence of protein S4, are strongly protected against ribonuclease digestion. The intermediate region (sections Q to M), however, is relatively accessible to ribonucleases in the S4-RNP. By partial removal of subfragments from the RNA complex it was possible to localise the two main interacting sites within sections H" - H and sections I" - C". Three main criteria for the specificity of the RNA-RNA interactions were invoked and satisfied. The possibility of other tertiary structural RNA-RNA interactions occurring in other regions of the 16S RNA is discussed. Finally, all the structural information on the S4-RNP is summarised and a tentative model is proposed.

Base Sequence↗
PubMed1975

Primary sequence of the 16S ribosomal RNA of Escherichia coli.

Recent progress in the nucleotide sequence analysis of the 16S ribosomal RNA from E. coli is described. The sequence which has been partially or completely determined so far encompasses 1520 nucleotides, i.e. about 95% of the molecule. Possible features of the secondary structure are suggested on the basis of the nucleotide sequence and data on sequence heterogeneities, repetitions and the location of modified nucleotides are presented. In the accompanying paper, the use of the nucleotide sequence data in studies of the ribosomal protein binding sites is described.

Bacterial Proteins↗
PubMed1975

Location and characteristics of ribosomal protein binding sites in the 16S RNA of Escherichia coli.

Specific binding sites for five proteins of the Escherichia coli 30S ribosomal subunit have been located within the 16S RNA. The sites are structurally diverse and range in size from 40 to 500 nucleotides; their functional integrity appears to depend upon both the secondary structure and conformation of the RNA molecule. Evidence is presented which indicates that additional proteins interact with the RNA at later stages of subunit assembly.

Bacterial Proteins↗
PubMed1974

Abnormal maturation of precursor 16S RNA in a ribosomal assembly defective mutant of E. coli.

The precursor and mature 16S ribosomal RNAs from a novel thermosensitive ribosomal assembly defective mutant of E. coli, in which genetic evidence suggests that the ribosomal protein S4 is altered, have been isolated and characterised by finger-printing methods. The precursor 16S RNA, which is accumulated at 42 degrees , appears to be identical with that present in wild-type strains, and with that previously described by other workers. However, the mature 16S RNA, which is contained in apparently normal functional 30S ribosomal particles synthesised at the growth-permissive temperature of 30 degrees , is incompletely trimmed and has either one or two additional nucleotides at its 5'-terminus. This might be due either to an accumulation of two late intermediates in the maturation process, or to mis-trimming of the RNA. Both possibilities suggest that the change in the protein S4 is not only responsible for the thermosensitive character of ribosomal assembly in this mutant, but also causes an alteration in the trimming site, affecting its recognition by the enzyme involved in the maturation.

Base Sequence↗
PubMed1972

Location of ribosomal protein binding sites on 16S ribosomal RNA.

The distribution of ribosomal protein binding sites on the 16S ribosomal RNA molecule has been analyzed by limited ribonuclease hydrolysis of RNA-protein complexes, as well as by the interaction of individual proteins with RNA fragments purified from partial enzymatic digests. Of the six 30S subunit proteins known to interact directly with 16S RNA, proteins S4, S8, S15, S20, and, probably, S13 bind within a fragment produced by T(1) RNase (12S RNA) that comprises some 900 nucleotides and covers almost the entire 5'-terminal half of the 16S molecule. A fragment of 500-600 nucleotides (8S RNA) that is contiguous with 12S RNA and arises from the 3'-terminal portion of the 16S molecule is believed to contain the binding site for protein S7. Protein S15 interacts specifically with a sequence of about 135 nucleotides (4S RNA) that derives from 12S RNA after more extensive hydrolysis. Protein S4, but none of the other ribosomal proteins, binds to a 500-nucleotide fragment (9S RNA), generated by pancreatic RNase, that lies at the 5'-terminus of 16S RNA and is completely overlapped by the 12S fragment. A preliminary map of the binding sites is presented.

Bacterial Proteins↗