RRC ID 53148
Author Tokizawa M, Kobayashi Y, Saito T, Kobayashi M, Iuchi S, Nomoto M, Tada Y, Yamamoto YY, Koyama H.
Title SENSITIVE TO PROTON RHIZOTOXICITY1, CALMODULIN BINDING TRANSCRIPTION ACTIVATOR2, and other transcription factors are involved in ALUMINUM-ACTIVATED MALATE TRANSPORTER1 expression.
Journal Plant Physiol
Abstract In Arabidopsis (Arabidopsis thaliana) the root apex is protected from aluminum (Al) rhizotoxicity by excretion of malate, an Al chelator, by ALUMINUM-ACTIVATED MALATE TRANSPORTER1 (AtALMT1). AtALMT1 expression is fundamentally regulated by the SENSITIVE TO PROTON RHIZOTOXICITY1 (STOP1) zinc finger protein, but other transcription factors have roles that enable Al-inducible expression with a broad dynamic range. In this study, we characterized multiple cis-elements in the AtALMT1 promoter that interact with transcription factors. In planta complementation assays of AtALMT1 driven by 5' truncated promoters of different lengths showed that the promoter region between -540 and 0 (the first ATG) restored the Al-sensitive phenotype of atalm1 and thus contains cis-elements essential for AtALMT1 expression for Al tolerance. Computation of overrepresented octamers showed that eight regions in this promoter region contained potential cis-elements involved in Al induction and STOP1 regulation. Mutation in a position around -297 from the first ATG completely inactivated AtALMT1 expression and Al response. In vitro binding assays showed that this region contained the STOP1 binding site, which accounted for the recognition by four zinc finger domains of the protein. Other positions were characterized as cis-elements that regulated expression by repressors and activators and a transcription factor that determines root tip expression of AtALMT1. From the consensus of known cis-elements, we identified CALMODULIN-BINDING TRANSCRIPTION ACTIVATOR2 to be an activator of AtALMT1 expression. Al-inducible expression of AtALMT1 changed transcription starting sites, which increased the abundance of transcripts with a shortened 5' untranslated region. The present analyses identified multiple mechanisms that regulate AtALMT1 expression.
Volume 167(3)
Pages 991-1003
Published 2015-3
DOI 10.1104/pp.114.256552
PII pp.114.256552
PMID 25627216
PMC PMC4348791
MeSH Adaptation, Physiological / drug effects Aluminum / toxicity Arabidopsis / drug effects Arabidopsis / genetics* Arabidopsis / metabolism Arabidopsis Proteins / chemistry Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Base Sequence Gene Expression Profiling Gene Expression Regulation, Plant / drug effects Genetic Complementation Test Glucuronidase / metabolism Models, Biological Molecular Sequence Data Mutation / genetics Organic Anion Transporters / genetics Organic Anion Transporters / metabolism* Plants, Genetically Modified Promoter Regions, Genetic Protein Binding / drug effects Protein Structure, Tertiary RNA, Messenger / genetics RNA, Messenger / metabolism Staining and Labeling Transcription Factors / chemistry Transcription Factors / genetics Transcription Factors / metabolism* Transcription Initiation Site Transcription, Genetic / drug effects Zinc Fingers
IF 6.305
Times Cited 57
Resource
Arabidopsis / Cultured plant cells, genes sja05800