Dual targeting properties of the N-terminal signal sequence of Arabidopsis thaliana THI1 protein to mitochondria and chloroplasts

Dual targeting properties of the N-terminal signal sequence of Arabidopsis thaliana THI1 protein to mitochondria and chloroplasts

Autor Chabregas, S. M. Google Scholar
Luche, D. D. Google Scholar
Farias, L. P. Google Scholar
Ribeiro, A. F. Google Scholar
van Sluys, M. A. Google Scholar
Menck, CFM Google Scholar
Silva-Filho, M. C. Google Scholar
Instituição Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Resumo thi1 has been recently isolated from Arabidopsis thaliana and is probably involved in both thiamine biosynthesis and as protection of organellar DNA from damage. Studies of thiamine biosynthesis in plants suggests a plastid location for the pathway, which is in agreement with the predicted THI1 N-terminal chloroplastic transit peptide (TP). On the other hand, thiamine is synthesized in mitochondria in yeast cells. Interestingly, A. thaliana thi1 cDNA complements a yeast strain disrupted for the homologous gene. Analysis of THI1 amino acid sequence revealed the presence of a putative amphiphilic alpha -helix, which is typical for mitochondrial presequences, located downstream of the chloroplast transit peptide. To define the putative role of the two predicted targeting sequences in tandem, we produced two chimeric genes encompassing the chloroplastic THI1 TP and either 4 or 27 (including the putative mitochondrial presequence) N-terminal residues of the mature THI1, both linked to the reporter (gusA) gene. Analysis of GUS distribution in subcellular fractions of transgenic plants revealed that in the construct retaining only 4 residues of mature THI1, GUS was found in the chloroplastic fraction. Extension of the THI1 transit peptide to 27 residues of the mature protein allowed import and processing of GUS into both mitochondria and chloroplasts. Direct analysis by immunogold-labeling with an anti-THI1 polyclonal antibody identified THI1 in both organelles in Arabidopsis. We also provide evidence that the precursors of both organellar isoforms are encoded by a single nuclear transcript. Thus, THI1 is targeted simultaneously to mitochondria and chloroplasts by a post transcriptional mechanism.
Assunto chloroplasts
transit peptide
Idioma Inglês
Data 2001-08-01
Publicado em Plant Molecular Biology. Dordrecht: Kluwer Academic Publ, v. 46, n. 6, p. 639-650, 2001.
ISSN 0167-4412 (Sherpa/Romeo, fator de impacto)
Editor Kluwer Academic Publ
Extensão 639-650
Fonte http://dx.doi.org/10.1023/A:1011628510711
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000170787000001
URI http://repositorio.unifesp.br/handle/11600/26604

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