Intron-Mediated Enhancement of Gene Expression Independent of Unique Intron Sequences and Splicing1

• Published in: Plant physiology (Bethesda) Vol. 122; no. 2; pp. 535 - 542
• Main Authors: Rose, Alan B., Beliakoff, Jason A.
• Format: Journal Article
• Language: English
• Published: American Society of Plant Physiologists 01-02-2000
• ISSN: 0032-0889; 1532-2548

Either of the first two introns of the Arabidopsis tryptophan pathway gene
PAT1
elevates mRNA accumulation from a
PAT1
:β-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.