Biomaterial Database

Nucleotide sequence of the operators of lambda ultravirulent mutants. 1980

A Bailone, and F Galibert

The nucleotide sequence of the operators of ultravirulent mutants of lambda, able to grow on host cells with elevated repressor levels, was determined. It appears that ultravirulence in lambda requires multiple mutational events at the operator sequences. OL1, OL2, and OL3 operator sites are the target of mutational changes in ultravirulent phages indicating that these sites participate in vivo in repression of the PL promoter. No changes were found in the OR3 sequence, in contrast there is a mutation in OR2 and two mutations in OR1, in both lambda 668 and lambda 2668 phages. This mutated operator structure accounts for the constitutive expression of their PR promoter either in cells overproducing the lambda repressor or in cells overproducing the cro gene product. A model of the structure of the lambda operator site is proposed. The nucleotide sequence in each site can be divided into two functionally different subsets, one of which is recognized by the repressor while the other stabilizes the repressor-operator interaction.

UI	MeSH Term	Description	Entries
D008957	Models, Genetic	Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Genetic Models,Genetic Model,Model, Genetic
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
D009876	Operon	In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.	Operons
D010582	Bacteriophage lambda	A temperate inducible phage and type species of the genus lambda-like viruses, in the family SIPHOVIRIDAE. Its natural host is E. coli K12. Its VIRION contains linear double-stranded DNA with single-stranded 12-base 5' sticky ends. The DNA circularizes on infection.	Coliphage lambda,Enterobacteria phage lambda,Phage lambda,lambda Phage
D012097	Repressor Proteins	Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.	Repressor Molecules,Transcriptional Silencing Factors,Proteins, Repressor,Silencing Factors, Transcriptional
D005814	Genes, Viral	The functional hereditary units of VIRUSES.	Viral Genes,Gene, Viral,Viral Gene
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
D014774	Virulence	The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.	Pathogenicity