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In vivo assessment of the significance of phosphorylation of the Arabidopsis chloroplast protein import receptor, atToc33
Author(s) -
Aronsson Henrik,
Combe Jonathan,
Patel Ramesh,
Jarvis Paul
Publication year - 2006
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.12.055
Subject(s) - phosphorylation , phosphoserine , serine , transit peptide , microbiology and biotechnology , gtpase , arabidopsis , biology , chloroplast , protein phosphorylation , biochemistry , alanine , in vivo , mutant , chemistry , amino acid , protein kinase a , gene , genetics , plastid
atToc33 is a transit peptide receptor of the chloroplast outer envelope membrane, and possesses GTPase activity. In vitro, its transit peptide‐ and GTP‐binding properties are abrogated by its phosphorylation at serine 181, which was proposed to represent an important regulatory mechanism. We mutated S181 to alanine (to prevent phosphorylation), and to aspartate and glutamate (to mimic the effects of phosphoserine), and expressed all three proteins in ppi1 (atToc33 knockout) plants using the native promoter. The mutants complemented ppi1 with equal efficiency in respect of all criteria tested, including protein import efficiency and light stress tolerance. The data suggest that atToc33 phosphorylation may not play an important role in vivo.