THE PLANT CELL, Vol 1, Issue 2 201-208, Copyright © 1989 by American Society of Plant Biologists
Sequences Downstream of Translation Start Regulate Quantitative Expression of Two Petunia rbcS Genes
C. Dean, M. Favreau, D. Bond-Nutter, J. Bedbrook and P. Dunsmuir
Advanced Genetic Sciences, 6701 San Pablo Avenue, Oakland, California 94608
We investigated the basis for quantitative differences in leaf expression
of the petunia genes (rbcS) encoding the small subunit of ribulose
bisphosphate carboxylase. The most abundantly, SSU301, and the most weakly,
SSU911, expressed petunia rbcS genes maintained their differential
expression when transferred to tobacco, indicating that the determinants of
quantitative expression are intrinsic to these rbcS genes. Analysis of
chimeric genes in which the sequences of SSU301 and SSU911 had been
exchanged at the translation start showed that sequences both 5[prime] and
3[prime] to the start codon contribute to differences in steady-state mRNA
levels. The sequences 3[prime] to the translation initiation codon were
investigated by preparing chimeric genes in which sequences of the SSU301
and SSU911 were exchanged between each intron and at the translation
termination codon. The results showed that sequences downstream of the
coding region contribute to quantitative differences in expression of
SSU301 and SSU911, and nuclear run-on transcription experiments indicated
that the 3[prime] sequences affect transcription rates of the rbcS genes.
