Structure and expression of the Arabidopsis CaM-3 calmodulin gene.
Genomic and cDNA sequences encoding a calmodulin (CaM) gene from Arabidopsis (ACaM-3) have been isolated and characterized. ACaM-3 represents a sequence distinct from two previously isolated Arabidopsis CaM cDNA clones. A 2.3 kb Eco RI restriction fragment was sequenced and found to encode a complete CaM-coding sequence interrupted by a single 491 bp intron, together with 750 bp and 600 bp of 5' and 3' flanking sequences, respectively. The polypeptide encoded by ACaM-3 is identical to that encoded by ACaM-2 and it differs from the one encoded by ACaM-1 by four of 148 residues. The putative promoter of ACaM-3 was atypical of CaM genes previously isolated from animals in that it contained consensus TATA and CAAT box sequences and lacked GC-rich regions. Two DNA sequence elements closely resembling cyclic AMP regulatory elements, which have been identified in animal CaM genes, were located in the 5' flanking region of ACaM-3. Northern blot and polymerase chain reaction amplification assays confirmed that each of the three ACaM mRNAs were expressed in similar but distinct patterns in different organs. ACaM-1 mRNA was the only species detectable in root RNA fractions, and ACaM-3 mRNA could not be detected in floral stalks. Accumulation of the three CaM mRNAs in leaves was induced by a touch stimulus, but the kinetics and extent of the induction varied among the three mRNA species. Run-on transcription assays indicated that a portion of the differences in accumulation of ACaM-1, 2, and 3 mRNAs in leaves and siliques was attributable to differences in their net rates of transcription.
Perera
I Y
IY
Department of Plant Biology, University of Illinois, Urbana 61801.
Zielinski
R E
RE
D000595:Amino Acid Sequence; D001483:Base Sequence; D002147:Calmodulin / Q000235:genetics* / Q000378:metabolism; D004247:DNA; D005786:Gene Expression Regulation; D006234:Handling, Psychological; D007438:Introns; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010944:Plants / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D002147:Calmodulin; D012333:RNA, Messenger; D004247:DNA