site-directed mutagenesis

(noun)

Also called site-specific mutagenesis or oligonucleotide-directed mutagenesis, is a molecular biology technique often used in biomolecular engineering in which a mutation is created at a defined site in a DNA molecule.

Related Terms

Examples of site-directed mutagenesis in the following topics:

  • Mutation

    • Site-directed mutagenesis, also called site-specific mutagenesis or oligonucleotide-directed mutagenesis, is a molecular biology technique often used in biomolecular engineering in which a mutation is created at a defined site in a DNA molecule.
    • In general, this form of mutagenesis requires that the wild type gene sequence be known.
    • The copied gene contains the mutated site.
    • Many approaches have since been developed to improve the efficiency of mutagenesis.
    • In this experiment, random mutations were introduced into the virus by site-directed mutagenesis.

  • Shuttle Vectors and Expression Vectors

    • Expression vectors are used for molecular biology techniques such as site-directed mutagenesis.
    • They can also be used for in vitro experiments and modifications such as mutagenesis and PCR.
    • Please note the presence of a multiple cloning site, a promoter, a repressor, and a selectable marker.

  • Coupling Specific Genes to Specific Organisms Using PCR

    • Through site-directed mutagenesis or customized primers, individual mutations in DNA can be made.

  • Inactivating and Marking Target Genes with Transposons

    • Insertional mutagenesis is a technique used to study the function of genes.
    • Transposition is a precise process in which a defined DNA segment is excised from one DNA molecule and moved to another site in the same or different DNA molecule or genome.
    • An alternative strategy for insertional mutagenesis has been used in vertebrate animals to find genes that cause cancer.
    • Specifically, the transposon contains signals to truncate expression of an interrupted gene at the site of the insertion and then restart expression of a second truncated gene.

  • Gene Inversion

    • Recombining sequences in site-specific reactions are usually short and occur at a single target site within the recombining sequence.
    • For this to occur, there is typically one or more cofactors (to name a few: DNA-binding proteins and the presence or absence of DNA binding sites) and a site specific recombinase.
    • Fimbrial adhesion by the type I fimbriae in E. coli undergoes site specific inversion to regulate the expression of fimA, the major subunit of the pili, depending on the stage of infection.
    • The FimE recombinase has the capability to only invert the element and turn expression from on to off, while FimB can mediate the inversion in both directions.

  • Direct Damage

    • Direct damage to the host is a general mechanism utilized by pathogenic organisms to ensure infection and destruction of the host cell.
    • Direct damage to the host is a general mechanism utilized by pathogenic organisms to ensure infection and destruction of the host cell.
    • Pathogens that exhibit the ability to avoid contact utilize various processes to accomplish this, including: the ability to grow in regions of the body where phagocytes are incapable of reaching; the ability to inhibit the activation of an immune response; inhibiting and interfering with chemotaxis which drives the phagocytes to site of infection; and 'tricking' the immune system to identify the bacteria as 'self. ' Additional mechanism(s) by which bacteria can avoid destruction is by avoiding engulfment.
    • The production of these destructive products results in the direct damage of the host cell.
    • Fibrin clots will form at sites of injury, in this case, at the site of foreign invasion.

  • Pathogenicity Islands and Virulence Factors

    • Pathogenicity islands are discrete genetic units flanked by direct repeats, insertion sequences or tRNA genes, which act as sites for recombination into the DNA.
    • PAIs are flanked by direct repeats; the sequence of bases at two ends of the inserted sequence are the same.
    • PAIs are often associated with tRNA genes, which target sites for this integration event.

  • Pathogenicity Islands

    • Pathogenicity islands are discrete genetic units flanked by direct repeats, insertion sequences or tRNA genes, which act as sites for recombination into the DNA.
    • PAIs are flanked by direct repeats; the sequence of bases at two ends of the inserted sequence is the same.
    • PAIs are often associated with tRNA genes, which target sites for this integration event.

  • The AraC Regulator

    • The genes, araBAD and araC, are transcribed in opposite directions.
    • The araI1 and araI2 are DNA-binding sites that, when occupied by AraC, induce expression.
    • The two AraC-arabinose complexes bind to the araI site which promotes transcription.

  • Immediate Direct Examination of Specimen

    • For specimen collection at sites that normally contain resident microflora, care should be taken to sample only the infected site and not the surrounding areas.
    • Diagnostic laboratory techniques include direct testing using a microscope, immunological, or genetic methods that provide immediate clues as to the identity of the microbe or microbes in the sample, and cultivation, isolation, and identification of pathogens using a wide variety of general and specific tests (such as blood or other fluids).
    • The main phenotypic methods include the direct examination of specimens, observing the growth of specimen cultures on special media, and biochemical testing of specimen cultures.
    • Describe how immediate direct examination of a specimen is useful to determine microscopic and macroscopic morphology