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Activity determinants and functional specialization of Arabidopsis PEN1 syntaxin in innate immunity.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2008 Oct 03; Vol. 283 (40), pp. 26974-84. Date of Electronic Publication: 2008 Aug 04. - Publication Year :
- 2008
-
Abstract
- In eukaryotes, proteins of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family are believed to have a general role for the fusion of intracellular transport vesicles with acceptor membranes. Arabidopsis thaliana PEN1 syntaxin resides in the plasma membrane and was previously shown to act together with its partner SNAREs, the adaptor protein SNAP33, and endomembrane-anchored VAMP721/722 in the execution of secretory immune responses against powdery mildew fungi. We conducted a structure-function analysis of PEN1 and show that N-terminal phospho-mimicking and non-phosphorylatable variants neither affected binary nor ternary SNARE complex formation with cognate partners in vitro. However, expression of these syntaxin variants at native protein levels in a pen1 mutant background suggests that phosphorylation is required for full resistance activity in planta. All tested site-directed substitutions of SNARE domain or "linker region" residues reduced PEN1 defense activity. Two of the variants failed to form ternary complexes with the partner SNAREs in vitro, possibly explaining their diminished in planta activity. However, impaired pathogen defense in plants expressing a linker region variant is likely because of PEN1 destabilization. Although Arabidopsis PEN1 and SYP122 syntaxins share overlapping functions in plant growth and development, PEN1 activity in disease resistance is apparently the result of a complete functional specialization. Our findings are consistent with the hypothesis that PEN1 acts in plant defense through the formation of ternary SNARE complexes and point to the existence of unknown regulatory factors. Our data indirectly support structural inferences that the four-helical coiled coil bundle in ternary SNARE complexes is formed in a sequential order from the N- to C-terminal direction.
- Subjects :
- Arabidopsis genetics
Arabidopsis immunology
Arabidopsis microbiology
Arabidopsis Proteins genetics
Arabidopsis Proteins immunology
Ascomycota metabolism
Cell Membrane genetics
Cell Membrane immunology
Cell Membrane metabolism
Hordeum genetics
Hordeum immunology
Hordeum metabolism
Hordeum microbiology
Membrane Fusion genetics
Mutation
Phosphorylation
Plants, Genetically Modified genetics
Plants, Genetically Modified immunology
Plants, Genetically Modified metabolism
Plants, Genetically Modified microbiology
Protein Structure, Quaternary physiology
Protein Structure, Secondary physiology
Qa-SNARE Proteins genetics
Qa-SNARE Proteins immunology
Qb-SNARE Proteins genetics
Qb-SNARE Proteins immunology
Qb-SNARE Proteins metabolism
Qc-SNARE Proteins genetics
Qc-SNARE Proteins immunology
Qc-SNARE Proteins metabolism
Structure-Activity Relationship
Transport Vesicles genetics
Transport Vesicles immunology
Transport Vesicles metabolism
Zea mays genetics
Zea mays immunology
Zea mays metabolism
Zea mays microbiology
Arabidopsis metabolism
Arabidopsis Proteins metabolism
Immunity, Innate physiology
Plant Diseases genetics
Plant Diseases immunology
Qa-SNARE Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 283
- Issue :
- 40
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 18678865
- Full Text :
- https://doi.org/10.1074/jbc.M805236200