Pv. Shcherbakova et Yi. Pavlov, MUTAGENIC SPECIFICITY OF THE BASE ANALOG 6-N-HYDROXYLAMINOPURINE IN THE URA3 GENE OF THE YEAST SACCHAROMYCES-CEREVISIAE, Mutagenesis, 8(5), 1993, pp. 417-421
The mutational specificity of the base analog 6-N-hydroxyl-aminopurine
(HAP) was studied in the URA3 gene of the yeast Saccharomyces cerevis
iae. Twenty-nine independent HAP-induced ura3 mutations were sequenced
. GC --> AT transitions were found most frequently (21 out of 29) whil
e AT --> GC transitions were less abundant (five out of 29). Three GC
--> TA transversions were also detected. Two interesting features of D
NA context were revealed for transition mutations. One third of the tr
ansitions occurred at one site within short direct imperfect repeats c
onverting them to perfect repeats. A model involving complementary int
eraction of imperfect repeats is proposed to explain the origin of the
se mutations. Nearly all of the rest of the GC --> AT as well as the A
T --> GC transitions were found in the runs of several identical base
pairs, predominantly in the middle or at the 3' template nucleotide of
(G)n and (A)n runs.