Plant Physiol, February 2000, Vol. 122, pp. 535-542
Intron-Mediated Enhancement of Gene Expression Independent of
Unique Intron Sequences and Splicing1
Alan B.
Rose* and
Jason A.
Beliakoff2
Section of Molecular and Cellular Biology, University of
California, Davis, California 95616.
Either
of the first two introns of the Arabidopsis tryptophan pathway gene
PAT1 elevates mRNA accumulation from a
PAT1:
-glucuronidase (GUS) fusion roughly 5-fold
without affecting the rate of PAT1:GUS transcription. To
further explore the mechanism of this intron-mediated enhancement of
gene expression, we wanted to determine whether splicing or specific
intron sequences were necessary. In-frame derivatives of
PAT1 intron 1, whose splicing was prevented by a point
mutation or large deletions, were able to increase mRNA accumulation
from a PAT1:GUS fusion, demonstrating that splicing per
se is not required. Furthermore, each of a series of introns containing
overlapping deletions that together span PAT1 intron 1 increased PAT1:GUS mRNA accumulation as much as the
full-length intron did, indicating that all intron sequences are
individually dispensable for this phenomenon. These results eliminate
the simple idea that this intron stimulates mRNA accumulation via a
unique RNA-stabilizing sequence or through the completed act of
splicing. However, they are consistent with a possible role for
redundant intron sequence elements or an association of the pre-mRNA
with the spliceosome.
1
This work was supported by the U.S. Department
of Agriculture-National Research Initiatives Competitive Grants Program
(grant no. 97353014392).
2
Present address: Arizona Cancer Center,
University of Arizona, Tucson, AZ 85724.
*
Corresponding author; e-mail abrose{at}ucdavis.edu; fax
530-752-3085.
© 2000 American Society of Plant Physiologists
