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V Nene

Publications and source records attributed to V Nene.

58 records · Page 4Linked to original sources
PubMed1982

Genetic studies on the beta subunit of Escherichia coli RNA polymerase. I. The effect of known, single amino acid substitutions in an essential protein.

The use of five different nonsense suppressors, in conjunction with a collection of 95 independent, spontaneously-occurring amber mutants affecting expression of rpoB, allows the generation of a maximum of 475 potential variants of the beta subunit of E. coli RNA polymerase, each carrying a known amino acid substitution at a particular site. The effect of these amino acid exchanges has been investigated in vivo. A significant majority (363/475) of substitutions lead to cellular death and altered properties--temperature sensitivity, apparently altered transcription termination and a changed stringent response--indicating that RNA polymerase function (unlike that of dispensable proteins) is extremely sensitive to such single site changes.

DNA-Directed RNA Polymerases↗
PubMed1982

Genetic studies on the beta subunit of Escherichia coli RNA polymerase. II. Evidence that large N-terminal amber fragments of the beta subunit interfere with RNA polymerase function.

A collection of 95 independent, spontaneously-occurring mutants carrying amber lesions that affect expression of the beta gene, rpoB, has been isolated (see accompanying paper (Nene and Glass 1982)). Certain rpoB amber mutations act in trans, preventing a functional allele present on an F' plasmid from acting at high temperature. Two such temperature-sensitive rpoB(Am) strains are shown to produce large, N-terminal amber fragments. The possibility that these truncated polypeptides are the cause of this transdominant conditional-lethal phenotype is supported by analysis of fragment levels in thermoresistant survivors: the nonsense fragments are degraded at a significantly faster rate (half-lives 1.4- to 2.6-fold reduced) in Ts+ derivatives likely to carry second-site mutations within rpoB. We suggest that the beta fragments interfere with RNA polymerase function by interacting with one or more of the polymerase subunits.

DNA-Directed RNA Polymerases↗
PubMed1981

Direct measurement of absolute suppressor efficiency.

We have devised a system for measuring the degree of translational readthrough past a nonsense mutation which is based upon the quantitation of the two translation products, the suppressed polypeptide and the nonsense fragment. The absolute efficiency of four different amber suppressors (Su1, Su2, Su3, and Su7) has been determined at two unique amber sites in the structural gene for the beta subunit of Escherichia coli RNA polymerase.

DNA-Directed RNA Polymerases↗