Biomedical subjects

V L Singer

Publications and source records attributed to V L Singer.

21 records · Page 2Linked to original sources

PubMed1990

A wide variety of DNA sequences can functionally replace a yeast TATA element for transcriptional activation.

We created a library of DNA molecules in which the required TATA element of a yeast gal-his3 promoter is replaced by random-sequence oligomers averaging 16 bp in length. Surprisingly, 1% of such random sequences functionally replace the native yeast TATA element. In many cases, sequences completely unrelated to the consensus TATA element (TATAAA) stimulate transcription with equal or increased efficiency. Transcription mediated by these synthetic elements requires GAL4 and is initiated from normal his3 initiation sites, suggesting that it occurs by a mechanism indistinguishable from that involving wild-type TATA elements. Many, but not all, of these elements act as substrates for yeast TFIID in reconstituted transcription reactions in vitro. These observations indicate that yeast TFIID can stimulate transcription from TATA elements whose sequences differ from the consensus, and they suggest the possibility of alternative factors that may provide a related function for transcriptional activation.

Animals↗

PubMed1986

Characterization of heat shock in Bacillus subtilis.

We characterized the general properties of the heat shock response in Bacillus subtilis W168, B. subtilis JH642, and an spo0A mutant by using pulse-labeling of bacterial proteins and one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The transfer of cells from 37 to 50 degrees C repressed synthesis of most cellular proteins and led to the induction of at least 26 distinct heat shock proteins after about 3 min. Ethanol (4% [vol/vol]) induced a similar set of proteins, but somewhat more slowly. Synthesis of the majority of heat shock proteins at 50 degrees C returned to a steady-state level 20 to 40 min after the shock. Although no B. subtilis heat shock protein has yet been extensively characterized, three of these proteins were found to be immunologically related to the Escherichia coli heat shock proteins Dnak, Lon, and GroEL. Synthesis of both sigma 28 and sigma 43 proteins was sharply reduced during heat shock. Although a spo0A amber mutation blocks transcription from promoters used by at least two minor B. subtilis sigma factors, it did not alter the kinetics or general properties of the heat shock response.

Bacillus subtilis↗

PubMed1984

Isolation of sigma-28-specific promoters from Bacillus subtilis DNA.

Sigma-28-RNA polymerase is a minor form of RNA polymerase found in vegetative cells of Bacillus subtilis which utilizes promoter sites distinct from those recognized by the major RNA polymerase. We have isolated a collection of cloned B. subtilis DNA segments that contain in vitro promoter sites for sigma 28-RNA polymerase by screening a bacteriophage lambda library of B. subtilis genomic fragments. At least nine new sigma 28-specific promoter sites have been identified in this collection, and four have been partially mapped for further study. Our strategy employed a mix of RNA probes prepared by in vitro transcription with sigma 28-RNA polymerase of total B. subtilis DNA EcoRI and HindIII fragments. Over 70% of the unique clones identified contain sigma 28-specific promoter sites, suggesting that the method may have general application for identification of promoter-containing sequences. The efficiency with which sigma 28-specific promoters are detected is consistent with there being a relatively small number of such sites in the B. subtilis genome of which twelve have been cloned.

Bacillus subtilis↗