title: Human GLTP and mutant forms of ACD11 suppress cell death in the Arabidopsis acd11 mutant.
abstract: The Arabidopsis acd11 mutant exhibits runaway, programmed cell death due to the loss of a putative sphingosine transfer protein (ACD11) with homology to mammalian GLTP. We demonstrate that transgenic expression in Arabidopsis thaliana of human GLTP partially suppressed the phenotype of the acd11 null mutant, resulting in delayed programmed cell death development and plant survival. Surprisingly, a GLTP mutant form impaired in glycolipid transfer activity also complemented the acd11 mutants. To understand the relationship between functional complementarity and transfer activity, we generated site-specific mutants in ACD11 based on homologous GLTP residues required for glycolipid transfer. We show that these ACD11 mutant forms are impaired in their in vitro transfer activity of sphingolipids. However, transgenic expression of these mutant forms fully complemented acd11 mutant cell death, and transgenic plants showed normal induction of hypersensitive cell death upon infection with avirulent strains of Pseudomonas syringae. The significance of these findings with respect to the function(s) of ACD11 in sphingolipid transport and cell death regulation is discussed.
authors.affiliation: Department of Biology, University of Copenhagen, Copenhagen Biocenter, Denmark.
authors.forename: Nikolaj H T
authors.initials: NH
authors.lastname: Petersen
authors.forename: Lea V
authors.initials: LV
authors.lastname: McKinney
authors.forename: Helen
authors.initials: H
authors.lastname: Pike
authors.forename: Daniel
authors.initials: D
authors.lastname: Hofius
authors.forename: Asif
authors.initials: A
authors.lastname: Zakaria
authors.forename: Peter
authors.initials: P
authors.lastname: Brodersen
authors.forename: Morten
authors.initials: M
authors.lastname: Petersen
authors.forename: Rhoderick E
authors.initials: RE
authors.lastname: Brown
authors.forename: John
authors.initials: J
authors.lastname: Mundy
mesh_terms: D000595:Amino Acid Sequence; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000502:physiology*; D017931:DNA Primers; D006801:Humans; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: C451029:ACD11 protein, Arabidopsis; D051017:Apoptosis Regulatory Proteins; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D017931:DNA Primers; C511922:GLTP protein, human; D026901:Membrane Transport Proteins; D011994:Recombinant Proteins