PubMed · 5836343
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R Nassar, A Fraser. 1965-04-17. Selection and polygenes.. https://doi.org/10.1038/206323a0
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In neutrophils of a chronic granulomatous disease (CGD) patient with a lack of p67phox the mRNA for p67phox was present in normal amount and size. This mRNA was reverse transcribed, and the coding region was analyzed by single-strand conformation polymorphism analysis. Direct DNA sequencing allowed the identification of a A479-to-T and A481-to-G substitution in exon 5 of the p67phox gene resulting in a double nonconservative amino acid change 160Lys-to-Glu and 161Asp-to-Val (D160V-K161E). This defect was found in the genomic DNA of this patient in heterozygous state and does not correspond to those previously found in other cases of CGD lacking the p67phox.
Four series of plasmids (pNSI, pNSII, pNLI, and pNLII) with artificial polycistrons containing the lacZ test gene were constructed. These plasmids coded for polycistronic mRNAs with two different types of cistron (orfZ and lacZ) coupling: in pNSI and pNLI, the orfZ termination codon and the lacZ initiation codon overlapped (type I); in pNSII and pNLII, the orfZ termination codon, was located upstream of the lacZ SD sequence. The length of the orfZ cistron was 60 bp in pNSI and pNSII or 300 bp in pNLI and pNLII. Plasmids with the same type of cistron coupling contained the same lacZ translation initiation region, whereas the structure of the orfZ translation initiation region varied, thereby providing varying efficiency of the orfZ gene translation. The effect of these variations on the efficiency of the lacZ gene translation was evaluated by direct measurement of the beta-galactosidase activity in Escherichia coli cells transformed with the corresponding plasmids. We found that the level of translation of the distal lacZ gene depended on the ribosome stream from the proximal gene and was maximal at the optimal ribosome stream level, which, in turn, depended on the type of cistron coupling.