A Ds insertion alters the nuclear localization of the maize transcriptional activator R.
The R-sc gene of maize is a member of the R gene family of transcriptional activators that regulate anthocyanin biosynthesis. A derivative of R-sc, r-m9 conditions a reduced level of aleurone pigmentation due to the presence of a 2.1-kb Ds insertion near the 3' end of the coding region. Excision of Ds from r-m9 leaves a 7-bp insertion in the darker but still mutant v24 derivative. Both the 7-bp insertion in v24 and the 2.1-kb Ds in r-m9 are predicted to truncate their respective R proteins proximal to the carboxyl terminus, which was shown previously to contain one of three nuclear localization sequences. We find that the reduced expression of r-m9 and v24 are not due to mRNA or protein instability, but most likely reflect the inefficient localization of truncated R proteins to the nucleus. To our knowledge this is the first example of a transposable element insertion that alters gene expression by affecting nuclear localization. In addition, our data indicate that the carboxyl terminus of the R protein is far more important than previously suspected and illustrates the utility of natural mutations for defining functional domains in proteins.
Liu
Y
Y
Department of Botany, University of Georgia, Athens 30602, USA.
Alleman
M
M
Wessler
S R
SR
D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000096:biosynthesis; D001483:Base Sequence; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D017931:DNA Primers; D004251:DNA Transposable Elements; D017343:Genes, Plant; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D018515:Plant Leaves; D010940:Plant Proteins; D016133:Polymerase Chain Reaction; D018749:RNA, Plant / Q000096:biosynthesis; D012639:Seeds; D015534:Trans-Activators / Q000032:analysis / Q000096:biosynthesis*; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
D000872:Anthocyanins; D017931:DNA Primers; D004251:DNA Transposable Elements; D010940:Plant Proteins; C101487:R-sc protein, Zea mays; D018749:RNA, Plant; D015534:Trans-Activators