Abstract
ATP dependent protease Lon that is first discovered in Escherichia coli, has been identified in all organisms. In Arabidopsis, four genes have been annotated as Lon homologues and a gene At5g47040 encodes peroxisome-localized Lon, AtLon2. Our previous studies showed that the N-terminal domain of AtLon2 has molecular chaperone activities and the C-terminal domain act as a serine protease. The level of transcription of AtLon2 increased 2- to 4-fold by drought and high-salinity stresses and by ABA treatment. To clarify the physiological function of Lon2 in Arabidopsis, we analyzed a T-DNA insertion mutant lon2-1 and a RNA interference mutant lon2i. Transient expression assays using the particle bombardment method showed that the import efficiency of GFP-PTS1 in these mutants was lower than that in the wild type plant. The activity of β-oxidation was inhibited in the seedlings of mutants and the size of the lon2-1 plant was smaller than that of the wild type plant. These results suggested that AtLon2 is involved in protein import into peroxisomes and in establishment of pathway for lipid degradation.
