TY - JOUR
T1 - Alternative splicing of arabidopsis IBR5 pre-mRNA generates two IBR5 isoforms with distinct and overlapping functions
AU - Jayaweera, Thilanka
AU - Siriwardana, Chamindika
AU - Dharmasiri, Sunethra
AU - Quint, Marcel
AU - Gray, William M.
AU - Dharmasiri, Nihal
N1 - Funding Information:
We thank Drs. Bonnie Bartel and Teva Vernoux for sharing published materials, and Elia Lopez editorial assistance. This work was supported by the grants NSF (IOB-0845305) and Texas State University – One time (9000000525) (to N.D), NIH GM067203 (to W.G) and NSF DBI-0821252 (to JRK and DG).
PY - 2014/8/21
Y1 - 2014/8/21
N2 - The INDOLE-3-BUTYRIC ACID RESPONSE5 (IBR5 ) gene encodes a dual specificity phosphatase that regulates plant auxin responses. IBR5 has been predicted to generate two transcripts through alternative splicing, but alternative splicing of IBR5 has not been confirmed experimentally. The previously characterized ibr5-1 null mutant exhibits many auxin related defects such as auxin insensitive primary root growth, defective vascular development, short stature and reduced lateral root development. However, whether all these defects are caused by the lack of phosphatase activity is not clear. Here we describe two new auxin insensitive IBR5 alleles, ibr5-4, a catalytic site mutant, and ibr5-5, a splice site mutant. Characterization of these new mutants indicates that IBR5 is post-transcriptionally regulated to generate two transcripts, AT2G04550.1 and AT2G04550.3, and consequently two IBR5 isoforms, IBR5.1 and IBR5.3. The IBR5.1 isoform exhibits phosphatase catalytic activity that is required for both proper degradation of Aux/IAA proteins and auxin-induced gene expression. These two processes are independently regulated by IBR5.1. Comparison of new mutant alleles with ibr5-1 indicates that all three mutant alleles share many phenotypes. However, each allele also confers distinct defects implicating IBR5 isoform specific functions. Some of these functions are independent of IBR5.1 catalytic activity. Additionally, analysis of these new mutant alleles suggests that IBR5 may link ABP1 and SCFTIR1/AFBs auxin signaling pathways.
AB - The INDOLE-3-BUTYRIC ACID RESPONSE5 (IBR5 ) gene encodes a dual specificity phosphatase that regulates plant auxin responses. IBR5 has been predicted to generate two transcripts through alternative splicing, but alternative splicing of IBR5 has not been confirmed experimentally. The previously characterized ibr5-1 null mutant exhibits many auxin related defects such as auxin insensitive primary root growth, defective vascular development, short stature and reduced lateral root development. However, whether all these defects are caused by the lack of phosphatase activity is not clear. Here we describe two new auxin insensitive IBR5 alleles, ibr5-4, a catalytic site mutant, and ibr5-5, a splice site mutant. Characterization of these new mutants indicates that IBR5 is post-transcriptionally regulated to generate two transcripts, AT2G04550.1 and AT2G04550.3, and consequently two IBR5 isoforms, IBR5.1 and IBR5.3. The IBR5.1 isoform exhibits phosphatase catalytic activity that is required for both proper degradation of Aux/IAA proteins and auxin-induced gene expression. These two processes are independently regulated by IBR5.1. Comparison of new mutant alleles with ibr5-1 indicates that all three mutant alleles share many phenotypes. However, each allele also confers distinct defects implicating IBR5 isoform specific functions. Some of these functions are independent of IBR5.1 catalytic activity. Additionally, analysis of these new mutant alleles suggests that IBR5 may link ABP1 and SCFTIR1/AFBs auxin signaling pathways.
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U2 - 10.1371/journal.pone.0102301
DO - 10.1371/journal.pone.0102301
M3 - Article
C2 - 25144378
AN - SCOPUS:84929046351
SN - 1932-6203
VL - 9
JO - PloS one
JF - PloS one
IS - 8
M1 - e102301
ER -