title: Deletion of a chaperonin 60 beta gene leads to cell death in the Arabidopsis lesion initiation 1 mutant.
abstract: Lesion mimic mutants develop spontaneous cell death without pathogen attack. Some of the genes defined by these mutations may function as regulators of cell death, whereas others may perturb cellular metabolism in a way that leads to cell death. To understand the molecular mechanism of cell death in lesion mimic mutants, we isolated a lesion initiation 1 (len1) mutant by a T-DNA tagging method. The len1 mutant develops lesions on its leaves and expresses systemic acquired resistance (SAR). LEN1 was identified to encode a chloroplast chaperonin 60 beta (Cpn60 beta), a homologue of bacterial GroEL. The recombinant LEN1 had molecular chaperone activity for suppressing protein aggregation in vitro. Moreover, len1 plants develop accelerated cell death to heat shock stress in comparison with wild-type plants. The chlorophyll a/b binding protein (CAB) was present in len1 plants at a lower level than in the wild-type plants. These results indicate that LEN1 functions as a molecular chaperone in chloroplasts and its deletion leads to cell death in Arabidopsis.
authors.affiliation: Department of Bioscience, Fukui Prefectural University, Fukui, 910-1195 Japan. ishikawa@fpu.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ishikawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Masato
authors.initials: M
authors.lastname: Nakai
authors.forename: Tadashi
authors.initials: T
authors.lastname: Asahi
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics / Q000502:physiology; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D018834:Chaperonin 60 / Q000235:genetics* / Q000502:physiology; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D017353:Gene Deletion; D009154:Mutation; D016324:Sequence Tagged Sites; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013696:Temperature
chemical_list: D029681:Arabidopsis Proteins; D018834:Chaperonin 60