Biomedical subjects

F Hayes

Publications and source records attributed to F Hayes.

47 records · Page 3Linked to original sources

PubMed1980

30-S ribosomal subunit proteins of an Escherichia coli mutant in which assembly of the small ribosomal subunit is temperature-sensitive.

Escherichia coli 219ts2, a temperature-sensitive streptomycin-independent revertant of the streptomycin-dependent strain E. coli 209 is defective in 30-S ribosomal subunit assembly at 42 degrees C. Total 30-S ribosomal subunit proteins of this strain contain two additional components one of which (alpha) migrates below and the other (beta) to the right of protein S7 in two-dimensional polyacrylamide gel analyses carried out according to Kaltschmidt and Wittmann. These two components are also resolved from normal 30-S subunit proteins by chromatography on phosphocellulose. Tryptic fingerprinting of proteins alpha and beta identifies alpha as protein S7B, the form of S7 found in B strains of E. coli and beta as a mutant form of protein S4 produced by deletion of about 20 amino acids from the COOH terminus of the wild-type protein.

Amino Acids↗

PubMed1980

Defective assembly of the small ribosomal subunit in a temperature-sensitive mutant of Escherichia coli. Experiments in vitro.

Comparison of the properties in vitro of total 30-S ribosomal subunit proteins and purified protein S4 of Escherichia coli D10 (wild type) and E. coli 219ts2(temperature-sensitive) has given the following results. 1. Reconstitution of functional 30-S subunits in vitro occurs when total 30-S subunit proteins of either strain are used even at temperatures which are not permissive for 30-S subunit assembly in vivo in E. coli 219ts2. The yield of reconstitution is, however, twofold lower with 30-S subunit proteins of E. coli 219ts2 than with wild-type proteins. 2. The yield of complex formation between 16-S rRNA and protein S4 of E. coli 219ts2 is temperature-sensitive and lower at all temperatures tested (33-42 degrees C) than that observed when wild-type S4 is used. 3. The conformational stability of complexes between 16-S rRNA and S4 from 219ts2 is more temperature-sensitive than that of analogous complexes containing wild-type S4. These observations provide an explanation for the temperature sensitivity of 30-S subunit assembly in E. coli 219ts2.

Chromatography, Gel↗

PubMed1976

Processing of the 17-S Escherichia coli precursor RNA in the 27-S pre-ribosomal particle.

An RNase activity probably involved in the maturation of 16-S pre-ribosomal RNA in Escherichia coli has been partially purified from crude cell extracts. When 27-S ribosome precursor particles are incubated with this enzyme preparation in vitro, their 17-S RNA is converted to a product with the same electrophoretic mobility as mature 16-S rRNA. Fingerprint analysis of this product shows that it contains the 3'-OH but not the 5'-P terminus of mature 16-S rRNA. Generation of the normal 5'-P terminus seems to require a factor present in cell extracts since incubation of the 27-S precursor particle in an extract obtained after centrifugation at 30 000 x g causes conversion of the 17-S RNA to a 16-S species containing both termini of mature 16-S rRNA. Preliminary experiments suggest that correct maturation of the 5' end of the 17-S precursor RNA requires a system in which protein synthesis can take place.

Cell Fractionation↗

PubMed1976