Biomaterial Database

The use of a selectable FokI cassette in DNA replacement mutagenesis of the R388 dihydrofolate reductase gene. 1987

P S Vermersch, and G N Bennett

Department of Biochemistry, Rice University, Houston, TX 77251.

FokI, a class-IIS restriction endonuclease, cleaves double-stranded DNA to produce a protruding 5' end consisting of four nucleotides, 10-13 residues 3' from the nonpalindromic recognition sequence, GGATG. Cassettes which utilize this separation of cleavage and recognition site have been constructed for the purpose of linker mutagenesis and DNA replacement experiments. The cassettes are flanked by FokI recognition sequences oriented such that the FokI cleavage sites are several nucleotides beyond the cassette/vector fusion sites. FokI excises the cassette and several base pairs of the neighboring vector sequence. The ends produced in the vector by FokI cleavage are generally noncomplementary and suitable for the insertion of a segment of synthesized double-stranded replacement DNA. A cassette which contains a tyrosine tRNA suppressor gene (supF) is selectable by the suppression of amber mutations in the recipient host. A vector containing a pBR322-derived origin of replication, the Escherichia coli xanthine-guanine phosphoribosyl transferase gene as a selectable marker, and no FokI sites has been constructed for use with the FokI cassettes. An experiment which utilized the FokI/supF cassette to modify the N-terminal coding region of the R388 dihydrofolate reductase gene is described.

UI	MeSH Term	Description	Entries
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
D010957	Plasmids	Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.	Episomes,Episome,Plasmid
D004262	DNA Restriction Enzymes	Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of DNAs, and have made it possible to splice and recombine genes from one organism into the genome of another. EC 3.21.1.	Restriction Endonucleases,DNA Restriction Enzyme,Restriction Endonuclease,Endonuclease, Restriction,Endonucleases, Restriction,Enzymes, DNA Restriction,Restriction Enzyme, DNA,Restriction Enzymes, DNA
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
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
D005796	Genes	A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.	Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D005822	Genetic Vectors	DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition.	Cloning Vectors,Shuttle Vectors,Vectors, Genetic,Cloning Vector,Genetic Vector,Shuttle Vector,Vector, Cloning,Vector, Genetic,Vector, Shuttle,Vectors, Cloning,Vectors, Shuttle
D005838	Genotype	The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.	Genogroup,Genogroups,Genotypes
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