Biomaterial Database

5'-Terminal nucleotide sequence of Escherichia coli lactose repressor mRNA: features of translational initiation and reinitiation sites. 1977

D A Steege

In a sequence of 214 nucleotides at the 5' terminus of the I gene mRNA, which codes for the lactose repressor protein of Escherichia coli, (i) an untranslated leader sequence of 28 residues precedes the repressor coding region; (ii) a GUG initiates synthesis of the wild-type repressor; (iii) GUG and AUG are the functional initiators for the synthesis of restart polypeptides activated by early I gene amber mutations, confirming previous assignments for these residues based on protein sequencing data; and (iv) sequences complementary to 16S ribosomal RNA provide stronger potential mRNA.16S rRNA interaction at the wild-type initiation site than at the restart sites. When I mRNA is used to direct the formation of initiation complexes in vitro, ribosomes bind only to the wild-type initiator region.A striking feature of the I mRNA sequence is the presence of a number of in-phase GUGs that have not been observed to serve as initiation signals in vivo in the nonsense mutant strains examined. The selective use of potential initiator triplets in the I mRNA leads to the following conclusions. First, when presented with several neighboring initiator triplets at the wild-type initiator region, ribosomes select the one preceded by the strongest appropriately positioned complementarity to the 16S 3' end. Second, ribosomes do not restart after termination simply by moving to the next available initiator codon. Third, the formation of stable secondary structures predicted for the untranslated I mRNA beyond chain-terminating nonsense mutations may prevent ribosome access to some potential reinitiation sites.

UI	MeSH Term	Description	Entries
D007785	Lactose	A disaccharide of GLUCOSE and GALACTOSE in human and cow milk. It is used in pharmacy for tablets, in medicine as a nutrient, and in industry.	Anhydrous Lactose,Lactose, Anhydrous
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D009841	Oligonucleotides	Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (OLIGONUCLEOTIDE PROBES). (Dorland, 28th ed)	Oligonucleotide
D010442	Peptide Chain Initiation, Translational	A process of GENETIC TRANSLATION whereby the formation of a peptide chain is started. It includes assembly of the RIBOSOME components, the MESSENGER RNA coding for the polypeptide to be made, INITIATOR TRNA, and PEPTIDE INITIATION FACTORS; and placement of the first amino acid in the peptide chain. The details and components of this process are unique for prokaryotic protein biosynthesis and eukaryotic protein biosynthesis.	Chain Initiation, Peptide, Translational,Protein Biosynthesis Initiation,Protein Chain Initiation, Translational,Protein Translation Initiation,Translation Initiation, Genetic,Translation Initiation, Protein,Translational Initiation, Protein,Translational Peptide Chain Initiation,Biosynthesis Initiation, Protein,Genetic Translation Initiation,Initiation, Genetic Translation,Initiation, Protein Biosynthesis,Initiation, Protein Translation,Initiation, Protein Translational,Protein Translational Initiation
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005809	Genes, Regulator	Genes which regulate or circumscribe the activity of other genes; specifically, genes which code for PROTEINS or RNAs which have GENE EXPRESSION REGULATION functions.	Gene, Regulator,Regulator Gene,Regulator Genes,Regulatory Genes,Gene, Regulatory,Genes, Regulatory,Regulatory Gene
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D012270	Ribosomes	Multicomponent ribonucleoprotein structures found in the CYTOPLASM of all cells, and in MITOCHONDRIA, and PLASTIDS. They function in PROTEIN BIOSYNTHESIS via GENETIC TRANSLATION.	Ribosome
D012329	RNA, Bacterial	Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.	Bacterial RNA