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Biomedical subjects

J F Atkins

Publications and source records attributed to J F Atkins.

116 records · Page 7Linked to original sources
PubMed1974

Cell-free synthesis of adenovirus 2 proteins programmed by fractionated messenger RNA: a comparison of polypeptide products and messenger RNA lengths.

Cytoplasmic RNA extracted from human tissue culture cells infected with adenovirus type 2 was used to program protein synthesis in a cell-free system derived from mammalian cells. Analysis of the protein product by polyacrylamide gel electrophoresis revealed ten adenovirus-specific polypeptides. Five of these were further identified by analysis of tryptic peptides. Translation of RNA fractionated by sedimentation through sucrose gradients containing formamide demonstrated seven size classes of RNA, each of which programmed the synthesis of only one or two virus-specific polypeptides. Six of the virus-specific polypeptides were translated from RNAs much larger than expected for the size of the polypeptide.

Adenoviridae↗
PubMed1972

Low activity of -galactosidase in frameshift mutants of Escherichia coli.

16 lac frameshift mutants induced by an acridine derivative, ICR-191D, in E. coli are leaky for beta-galactosidase activity. Activities of all mutants differ from each other and from the wild type in their stability to thermal denaturation. The leakiness is under ribosomal control, since it is strongly reduced by strA restrictive mutations and is restored by ram mutations that reverse restriction. Addition of streptomycin during growth has an effect similar to the presence of the ram mutation. These ribosomal alterations do not modify the thermal stability of the enzyme.It is suggested that the leakiness is due to an infrequent 2- or 4-base reading close to the frameshift mutation site. The possibility that not only the ribosome, but also the reading context in the messenger, plays a role in securing code fidelity is discussed.

Acridines↗
PubMed1971

Histidinol dehydrogenase (his D) mutants of Salmonella typhimurium.

A multidisciplinary analysis has been applied to over 150 hisD mutants of Salmonella typhimurium in a study of gene-enzyme relationship. The mutants were examined for production of immunologically cross-reacting material by using antibody to purified histidinol dehydrogenase, and for genetic complementation by using a set of F' factors bearing Escherichia coli hisD complementing mutants. Classifications as to missense, nonsense, frameshift, or deletion mutant are proposed on the basis of mutagenesis and suppression tests. For the suppression tests the mutants were examined both by a simultaneous suppression technique and by testing for response to E. coli F' factors bearing a recessive lethal amber and a recessive lethal ochre suppressor. The data are interpreted in relation to the position of the mutations in the recombination and complementation maps and in relation to the known composition of histidinol dehydrogenase. The gene hisD appears to be single cistron for the production of a single biosynthetic polypeptide.

Acridines↗
PubMed1970

Transcription initiation in the histidine operon of Salmonella typhimurium.

Evidence is presented for two natural transcription initiators positioned internally in the histidine operon of Salmonella typhimurium. They were detected using highly polar S. typhimurium his mutants as recipients for F' Escherichia coli his episomes. These intergeneric complementation tests provide a sensitive method for the detection of other initiators and of terminators. That at least part of the operator for the his operon lies distal to the transcription initiator is suggested by transduction analysis of a new highly polar mutant described in this paper.

Escherichia coli↗
PubMedDate not supplied

Upstream stimulators for recoding.

Recent progress in elucidation of 5' stimulatory elements for translational recoding is reviewed. A 5' Shine-Dalgarno sequence increases both +1 and -1 frameshift efficiency in several genes; examples cited include the E. coli prfB gene encoding release factor 2 and the dnaX gene encoding the gamma and tau subunits of DNA polymerase III holoenzyme. The spacing between the Shine-Dalgarno sequence and the shift site is critical in both the +1 and -1 frameshift cassettes; however, the optimal spacing is quite different in the two cases. A frameshift in a mammalian chromosomal gene, ornithine decarboxylase antizyme, has recently been reported; 5' sequences have been shown to be vital for this frameshift event. Escherichia coli bacteriophage T4 gene 60 encodes a subunit of its type II DNA topoisomerase. The mature gene 60 mRNA contains an internal 50 nucleotide region that appears to be bypassed during translation. A 16 amino acid domain of the nascent peptide is necessary for this bypass to occur.

Animals↗