Mutations deletion, production

Frameshift Mutation. Deletion or insertion of a base or bases that alters the reading frame of the gene. In contrast to base substitution mutations where the mutation often has no consequence to the gene function or has only a partial effect on the gene function, a frameshift mutation completely changes the amino acid sequence downstream of the mutation site within a proteincoding gene. Thus, frameshift mutation is a severe type of mutation, which results in inactivation of the protein product most of the time. 

Coeffet-Le Gal, M.F., Thurston, L., Rich, P. et al. (2006) Complementation of daptomycin dpt A and dptD deletion mutations in trans and production of hybrid lipopeptide antibiotics. Microbiology (Reading, England), 152,2993. 

Some 70 per cent of all cystic fibrosis patients exhibit a specific three-base-pair deletion in the gene, which results in the loss of a single amino acid (phenylalanine 508) from its final polypeptide product. Other cystic fibrosis patients display various other mutations in the same gene. 

It is often difficult to distinguish a mutation, which causes a completely inactive protein to be produced instead of an enzyme, from an effective deletion of the gene, when neither protein nor enzyme is produced. If, however, a mutation causes a protein with weak enzymatic properties to be produced, the abnormal homozygote will be able to carry out the reaction, though at a lower rate than the normal the product of such a mutation is termed a leaky gene. ... 

After designing the primers, the rest of the procedure is the same as that for the mutated internal standard construction. In brief, the first amplification consists of two separate PCR protocols to generate the two halves of the internal standard. In the first PCR protocol, primers 1 and 3 are used and the upstream half of primer 3 anneals to the site just 5 to the intended deletion. In the second PCR, we employ primers 2 and 4 for amplification. Each of these amplification procedures results in one-half of the internal standard containing the deletion mutation in the middle of a 34-bp sequence at one end, which will allow the halves to anneal to each other. The products of these separate PCRs are separated on a 1.2% low melting temperature gel to check the size of the amplicons, which are then purified by gel extraction as described for the mutated internal standard construction. 

SCF is encoded by the mouse Steel (SI) loci (Zsebo et al, 1990). The Sl-Dickie allele of mutant mice (Sf ) encodes a smaller protein due to deletions of the transmembrane and intracellular domains. SI cells exclusively express a secreted form of SCF (Flanagan et al, 1991). Another mutation of the Steel locus, Sl/Sl, results in complete loss of SCF production (Zsebo et al, 1990). Mutations of both the Steel and SI loci result in similar phenotypic disorders of hematopoiesis characterized by reduction in stem cell numbers, anemia, mast cell- and repair deficiencies (Nocka et al., 1989 McCulloch et al., 1965). Phenotypes of Sf mice show that the membrane inserted SCF must have an... 

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