CGI-58, a key regulator of lipid homeostasis and signaling in plants, also regulates polyamine metabolism.
Comparative Gene Identification-58 (CGI-58) is an α/β hydrolase-type protein that regulates lipid homeostasis and signaling in eukaryotes by interacting with and stimulating the activity of several different types of proteins, including a lipase in mammalian cells and a peroxisomal ABC transporter (PXA1) in plant cells. Here we show that plant CGI-58 also interacts with spermidine synthase 1 (SPDS1), an enzyme that plays a central role in polyamine metabolism by converting putrescine into spermidine. Analysis of polyamine contents in Arabidopsis thaliana plants revealed that spermidine levels were significantly reduced, and putrescine increased, in both cgi-58 and cgi-58/pxa1 mutant plants, relative to pxa1 mutant or wild-type plants. Evaluation of polyamine-related gene expression levels, however, revealed similar increases in transcript abundance in all mutants, including cgi-58, pxa1, and cgi-58/pxa1, in comparison to wild type. Taken together, the data support a model whereby CGI-58 and PXA1 contribute to the regulation of polyamine metabolism at the transcriptional level, perhaps through a shared lipid-signaling pathway, and that CGI-58 also acts independently of PXA1 to increase spermidine content at a post-transcriptional level, possibly through protein-protein interaction with SPDS1.
USDA-ARS; US Arid-Land Agricultural Research Center; Maricopa, AZ USA; Department of Biological Sciences; Center for Plant Lipid Research; University of North Texas; Denton, TX USA.
Sunjung
S
Park
Department of Biological Sciences; Center for Plant Lipid Research; University of North Texas; Denton, TX USA.
Jantana
J
Keereetaweep
Department of Biological Sciences; Center for Plant Lipid Research; University of North Texas; Denton, TX USA.
Christopher N
CN
James
Department of Molecular and Cellular Biology; University of Guelph; Guelph, ON Canada.
Satinder K
SK
Gidda
Department of Biological Sciences; Center for Plant Lipid Research; University of North Texas; Denton, TX USA.
Kent D
KD
Chapman
Department of Molecular and Cellular Biology; University of Guelph; Guelph, ON Canada.
Robert T
RT
Mullen
USDA-ARS; US Arid-Land Agricultural Research Center; Maricopa, AZ USA.
John M
JM
Dyer
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000251:Adenosine Triphosphatases; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006706:Homeostasis; D050356:Lipid Metabolism; D009154:Mutation / Q000235:genetics; D011073:Polyamines / Q000378:metabolism*; D015398:Signal Transduction; D011436:Spermidine Synthase
D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D011073:Polyamines; D000217:Acyltransferases; C018764:2-acylglycerophosphate acyltransferase; C470419:SPDS1 protein, Arabidopsis; D011436:Spermidine Synthase; D000251:Adenosine Triphosphatases; C456843:At4g39850 protein, Arabidopsis
Arabidopsis; CGI-58; PXA1; Polyamines; SPDS1; Spermidine; Spermidine Synthase