Novel alternative splicing of mRNAs encoding poly(A) polymerases in Arabidopsis.
The Arabidopsis thaliana genome possesses four genes whose predicted products are similar to eukaryotic poly(A) polymerases from yeasts and animals. These genes are all expressed, as indicated by RT/PCR and Northern blot analysis. The four Arabidopsis PAPs share a conserved N-terminal catalytic core with other eukaryotic enzymes, but differ substantially in their C-termini. Moreover, one of the four Arabidopsis enzymes is significantly shorter than the other three, and is more divergent even within the conserved core of the protein. Nonetheless, the protein encoded by this gene, when produced in and purified from E. coli, possesses nonspecific poly(A) polymerase activity. Genes encoding these Arabidopsis PAPs give rise to a number of alternatively spliced mRNAs. While the specific nature of the alternative splicing varied amongst these three genes, mRNAs from the three "larger" genes could be alternatively spliced in the vicinity of the 5th and 6th introns of each gene. Interestingly, the patterns of alternative splicing vary in different tissues. The ubiquity of alternative splicing in this gene family, as well as the differences in specific mechanisms of alternative processing in the different genes, suggests an important function for alternatively spliced PAP mRNAs in Arabidopsis.
Plant Physiology/Biochemistry/Molecular Biology Program and Department of Agronomy, University of Kentucky, 301A Plant Science Building, 1405 Veterans Road, Lexington, KY 40546-0312, USA.
Balasubrahmanyam
B
Addepalli
Lisa R
LR
Meeks
Kevin P
KP
Forbes
Arthur G
AG
Hunt
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics*; D001419:Bacteria; D005658:Fungi; D007527:Isoenzymes / Q000235:genetics; D008969:Molecular Sequence Data; D011062:Polynucleotide Adenylyltransferase / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment
D007527:Isoenzymes; D012333:RNA, Messenger; D011062:Polynucleotide Adenylyltransferase