[Possibility of using fusion proteins for detection of nonsense mutations and frame-shift mutations in BRCA1 gene].
The aim of this study was to evaluate the possibility of detecting nonsense and frame-shift mutations in exon 11 of brca1 gene by constructing fusion open reading frame (ORF) "exon 11 ORF-alpha-peptide of beta-galactosidase". The ability/inability of this newly constructed ORF to cause alpha-complementation in E. coli delta M15gal cells transformed by the plasmid with the ORF may reflect the absence/presence of nonsense and frame-shift mutations in the studied fragment. A single ORF fragment of exon 11 of brca1 gene--LacZ' gene was designed in pGEN7Zf plasmid, the plasmid was shown to cause Lac+ phenotype in E. coli delta M15gal. Four frame-shift deletion mutations were introduced into exon 11 sequence in the plasmid. Surprisingly, the frame-shift deletion mutations did not influence the ability of plasmids to induce Lac+ phenotype in E. coli delta M15gal in 3 cases and only one deletion mutation resulted in inability of the plasmid to form Lac+ phenotype in E. coli delta M15gal. We suppose that the phenomenon can be explained by the alpha-peptide translation reinitiation from inframe ATG codons situated within the exon 11 sequence. Seven inframe ATG sequences were found in exon 11, at least two in-frame ATG-containing fragments were demonstrated to cause reinitiation. On the other hand, the only deletion mutation resulted in inability of the plasmid to form Lac+ phenotype in E. coli delta M15gal did not leave LacZ' in-frame ATG in econ 11 sequence. We conclude that it is possible to detect frame-shift mutations by in-frame cloning with the LacZ' reporter gene, but this possibility is strongly impeded by the reinitiation of alpha-peptide translation from the in-frame ATG codons within the studied sequence.
Gutkina
N I
NI
Institute of Molecular Biology and Biophysics, Siberian Division of Russian Academy of Medical Sciences.
Gaĭdamakova
E K
EK
Varlakhanova
N V
NV
Kovalenko
S P
SP
D019313:BRCA1 Protein / Q000235:genetics*; D018389:Codon, Nonsense; D004252:DNA Mutational Analysis / Q000379:methods*; D004926:Escherichia coli / Q000235:genetics; D005091:Exons; D016368:Frameshift Mutation; D006801:Humans; D010957:Plasmids; D014176:Protein Biosynthesis; D011993:Recombinant Fusion Proteins / Q000235:genetics*; D001616:beta-Galactosidase / Q000235:genetics*
D019313:BRCA1 Protein; D018389:Codon, Nonsense; D011993:Recombinant Fusion Proteins; D001616:beta-Galactosidase