ISSN:
1573-4927
Schlagwort(e):
mutagenesis
;
alcohol dehydrogenase
;
formaldehyde
;
Drosophila
;
deletions
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Chemie und Pharmazie
Notizen:
Abstract Adh fn23 andAdh fn24 are two formaldehyde-induced, homozygous-viable, alcohol dehydrogenase-null mutants that bear lesions in the gene tht codes for the alcohol dehydrogenase (ADH; EC 1.1.1.1) ofDrosophila melanogaster. Adh fn23 contains a 34-base pair deletion in the C-terminal coding region of the alcohol dehydrogenase structural gene. By immunological and molecular analysis, we show that the deletion shifts the translation reading frame and results in a prematurely truncated polypeptide product (10 amino acids shorter than wild type) that cross-reacts with antibody raised against ADH. The steady-state level of alcohol dehydrogenase mRNA present in this mutant is close (97%) to that in the wild type, but the steady-state level of alcohol dehydrogenase-like protein is 50% lower. Moreover, the rate of alcohol dehydrogenase synthesis inAdh fn23 flies is reduced to 60% of that found in the wild type. Hence both the rate of synthesis and the rate of degradation of alcohol dehydrogenase are affected. In contrast,Adh fn24 which contains an 11-base pair deletion in the N-terminal coding region of the ADH gene, synthesizes no immunodetectable protein, and the amount of alcohol dehydrogenase mRNA is less than half that of wild-type flies. As withAdh fn23, the deletion inAdh fn24 results in a change in the reading frame. UnlikeAdh fn23, however, nucleic acid sequence data indicate that polypeptide chain elongation can proceed for a considerable distance (over 130 amino acids) beyond the deletion. Based upon antigenic binding-site predictions, the resultant aberrant protein (projected 195 amino acids in length) would share few antigenic sites with the alcohol dehydrogenase from the wild type, which may account for the lack of immunoprecipitable material in this mutant. The contrasting effects these two deletions have on theDrosophila ADH mRNA levels and ADH protein levels are discussed.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00556207
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