title: Analysis of Arabidopsis glucose insensitive growth mutants reveals the involvement of the plastidial copper transporter PAA1 in glucose-induced intracellular signaling.
abstract: Sugars play important roles in many aspects of plant growth and development, acting as both energy sources and signaling molecules. With the successful use of genetic approaches, the molecular components involved in sugar signaling have been identified and their regulatory roles in the pathways have been elucidated. Here, we describe novel mutants of Arabidopsis (Arabidopsis thaliana), named glucose insensitive growth (gig), identified by their insensitivity to high-glucose (Glc)-induced growth inhibition. The gig mutant displayed retarded growth under normal growth conditions and also showed alterations in the expression of Glc-responsive genes under high-Glc conditions. Our molecular identification reveals that GIG encodes the plastidial copper (Cu) transporter PAA1 (for P(1B)-type ATPase 1). Interestingly, double mutant analysis indicated that in high Glc, gig is epistatic to both hexokinase1 (hxk1) and aba insensitive4 (abi4), major regulators in sugar and retrograde signaling. Under high-Glc conditions, the addition of Cu had no effect on the recovery of gig/paa1 to the wild type, whereas exogenous Cu feeding could suppress its phenotype under normal growth conditions. The expression of GIG/PAA1 was also altered by mutations in the nuclear factors HXK1, ABI3, and ABI4 in high Glc. Furthermore, a transient expression assay revealed the interaction between ABI4 and the GIG/PAA1 promoter, suggesting that ABI4 actively regulates the transcription of GIG/PAA1, likely binding to the CCAC/ACGT core element of the GIG/PAA1 promoter. Our findings indicate that the plastidial Cu transporter PAA1, which is essential for plastid function and/or activity, plays an important role in bidirectional communication between the plastid and the nucleus in high Glc.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Korea.
authors.forename: Shin Ae
authors.initials: SA
authors.lastname: Lee
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Yoon
authors.forename: Jung-Ok
authors.initials: JO
authors.lastname: Heo
authors.forename: Mi-Hyun
authors.initials: MH
authors.lastname: Lee
authors.forename: Indeok
authors.initials: I
authors.lastname: Hwang
authors.forename: Hyeonsook
authors.initials: H
authors.lastname: Cheong
authors.forename: Woo Sung
authors.initials: WS
authors.lastname: Lee
authors.forename: Yong-sic
authors.initials: YS
authors.lastname: Hwang
authors.forename: Jun
authors.initials: J
authors.lastname: Lim
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D025222:Chloroplast Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D004843:Epistasis, Genetic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D056426:Genetic Loci / Q000235:genetics; D005947:Glucose / Q000494:pharmacology*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics*; D018087:Plastids / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C470421:ABI4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D014157:Transcription Factors; D003300:Copper; D025222:Chloroplast Proton-Translocating ATPases; C477511:PAA1 protein, Arabidopsis; D005947:Glucose