DNA- dependent RNA-directed protein synthesis in vitro. I. Extent of genome transcription

Identification and Properties of the Messenger RNA Activity in Chlamydomonas reinhardi Coding for the Large Subunit of d-ribulose-1,5-bisphosphate Carboxylase

Properties of the mRNA coding for the large subunit of ribulose-1,5-bisphosphate carboxylase from Chlamydomonas reinhardi were determined. Large subunit synthesis, directed by RNA from partially purified whole cell extracts, was detected by specific immunoprecipitation of polypeptide products synthesized in a heterologous translation system derived from Escherichia coli. Large subunit synthesis showed sharp RNA concentration dependence in an E. coli translation system, and at optimal RNA concentrations, immunoprecipitable large subunit synthesis accounted for 2% of the total incorporation. Large subunit messenger activity sedimented at 12 to 14S on nondenaturing sucrose gradients and did not bind to oligo(dT)-cellulose suggesting the mRNA is not polyadenylated. The immunoprecipitable products translated in vitro are not complete polypeptide chains, but are smaller peptides identifiable as large subunit fragments by tryptic fingerprint analysis. No immunoprecipitable product was obtained when similar RNA fractions were tested in a wheat germ translation system.

Synthesis of mitochondrial proteins in an Escherichia coli cell-free system directed by yeast mitochondrial DNA

The optimum conditions for transcription in vitro of yeast mtDNA into biologically relevant RNA by Escherichia coli RNA polymerase holoenzyme and yeast mitochondrial RNA polymerase was found to critically depend on salt concentration. RNA was transcribed (at 0.25 M KCl concentration) from high-molecular-weight mtDNA which was then translated in an E. coli (S-30) cell-free protein synthesising system. Efficient translation of mitochondrial RNA was achieved using conditions which had also been determined to be optimal in other systems. Identification of the polypeptides produced in the translation system was made using antiserum raised against mitochondrial membranes. Electrophoresis of the completely dissociated antigen-antibody complexes using dodecylsulphate-polyacrylamide gels revealed that the system in vitro produced polypeptides of similar molecular weight to those synthesised in vivo by cycloheximide-inhibited whole cells.

DNA-dependent RNA-directed protein synthesis in vitro. IV. Peptide analysis of an in vitro and in vivo phi X174 structural protein

An antibody-precipitable structural protein from the bacteriophage varphiX174 was purified from an in vitro protein-synthesizing system primed with the replicative DNA of the virus. This protein was trypsin digested in the presence of the differentially labeled analogous protein that was purified from the bacteriophage. The tryptic hydrolysate was subjected to high resolution peptide chromatography which revealed essentially identical patterns for the varphiX174 proteins synthesized in vitro and in vivo.

Phi-X-174 bacteriophage structural mutants which affect deoxyribonucleic acid synthesis

Seven cistrons in phiX-174 were identified and one in particular was studied intensively: cistron A, which is assigned a protein in the mature phage. Amber mutants in this cistron synthesize a new deoxyribonucleic acid (DNA) form in addition to circular phage DNA upon infection of the restrictive host. This DNA is linear, non-infectious, and single-stranded; it is formed from the phage strand of replicative form phiX-174 DNA. These mutants produce two different defective particles in the restrictive host. One particle contains circular phage DNA but is not infectious; the other contains the new DNA form and is similar to the 70S particles found in wild-type phage lysates. The mutant A gene product acts independently of normal A protein upon mixed infection of the restrictive host with an A mutant and a mutant from any other cistron or wild type.

DNA-dependent RNA-directed protein synthesis in vitro, II. Synthesis of a phi-X-174 coat protein component

We present evidence to show that the primary protein product of an in vitro DNA-dependent RNA-directed protein-synthesizing system primed by varphiX-174 replicative form DNA comigrates in a gel electrophoresis system with a phage structural component. This protein component is precipitable by antiserum to purified phage.