Transposon-induced promoter scrambling: a mechanism for the evolution of new alleles.
We have studied a germinal revertant of the Mutator (Mu3)-induced mutation (Adh1-3F1124) of the maize alcohol dehydrogenase 1 gene (adh1). Transposon Mu3 was inserted at the TATA box of the promoter. The excision of Mu3 caused a complex, multibreakpoint DNA rearrangement with deletion, inverted duplication, and inversions affecting 430 nucleotides in the promoter region. These changes led to an unusual pattern of adh1 gene expression: increased levels of enzyme activity in one organ, decreased levels in another, and almost unchanged levels in a third organ. The evolutionary impact of transposon-induced promoter scrambling on generation of allelic diversity is discussed. We present a fragmentation model to help explain how transposon excision could induce multiple breakpoint aberrations without involving a homologous chromosome.
Kloeckener-Gruissem
B
B
Department of Plant Biology, University of California, Berkeley 94720.
Freeling
M
M
D000426:Alcohol Dehydrogenase / Q000096:biosynthesis / Q000235:genetics*; D000483:Alleles; D005075:Biological Evolution; D004251:DNA Transposable Elements; D017343:Genes, Plant; D008957:Models, Genetic; D016296:Mutagenesis; D011058:Pollen; D012333:RNA, Messenger / Q000096:biosynthesis; D018741:Replication Origin; D017384:Sequence Deletion; D016385:TATA Box; D003313:Zea mays / Q000201:enzymology / Q000235:genetics*
D004251:DNA Transposable Elements; D012333:RNA, Messenger; D000426:Alcohol Dehydrogenase