title: Biotin deficiency causes spontaneous cell death and activation of defense signaling.
abstract: In addition to its essential metabolic functions, biotin has been suggested to play a critical role in regulating gene expression. The first committed enzyme in biotin biosynthesis in Arabidopsis, 7-keto-8-aminopelargonic acid synthase, is encoded by At5g04620 (BIO4). We isolated a T-DNA insertion mutant of BIO4 (bio4-1) with a spontaneous cell death phenotype, which was rescued both by exogenous biotin and genetic complementation. The bio4-1 plants exhibited massive accumulation of hydrogen peroxide and constitutive up-regulation of a number of genes that are diagnostic for defense and reactive oxygen species signaling. The cell-death phenotype was independent of salicylic acid and jasmonate signaling. Interestingly, the observed increase in defense gene expression was not accompanied by enhanced resistance to bacterial pathogens, which may be explained by uncoupling of defense gene transcription from accumulation of the corresponding protein. Characterization of biotinylated protein profiles showed a substantial reduction of both chloroplastic biotinylated proteins and a nuclear biotinylated polypeptide in the mutant. Our results suggest that biotin deficiency results in light-dependent spontaneous cell death and modulates defense gene expression. The isolation and molecular characterization of the bio4-1 mutant provides a valuable tool for elucidating new functions of biotin.
authors: Division of Genetics, Department of Biosciences, Viikki Biocenter, University of Helsinki, 00014 Helsinki, Finland.
authors: Jing
authors: J
authors: Li
authors: Günter
authors: G
authors: Brader
authors: Elina
authors: E
authors: Helenius
authors: Tarja
authors: T
authors: Kariola
authors: E Tapio
authors: ET
authors: Palva
mesh_terms: D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001710:Biotin / Q000378:metabolism* / Q000494:pharmacology; D015153:Blotting, Western; D016923:Cell Death / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D054884:Host-Pathogen Interactions; D006861:Hydrogen Peroxide / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D016973:Pectobacterium carotovorum / Q000502:physiology; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010937:Plant Growth Regulators / Q000378:metabolism; D044224:Pseudomonas syringae / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D001710:Biotin; D006861:Hydrogen Peroxide; D000217:Acyltransferases; C021929:8-amino-7-oxononanoate synthase