Cap-independent translation of maize Hsp101
Por:
Dinkova T.D., Zepeda H., Martínez-Salas E., Martínez L.M., Nieto-Sotelo J., Sánchez De Jiménez E.
Publicada:
1 ene 2005
Resumen:
Maize embryonic axes contain stored mRNAs, some of which are able to undergo cap-independent translation initiation during germination. The Hsp101 mRNA, encoding a heat shock protein, is essential for thermotolérance induction and is present among the stored transcripts. This research aimed to investigate whether the Hsp101 transcript is IRES-driven regulated upon heat stress. Hsp101 transcribed either in vitro or in vivo was efficiently translated via a cap-independent mechanism. This was observed either in an animal in vitro translation system containing proteolytically cleaved eukaryotic initiation factor elF4G or in a plant system lacking both elF4E and elFiso4E initiation factors. Deletion of the 5? untranslated region (UTR) from the Hsp101 mRNA abolished its cap-independent translation indicating that this nucleotide sequence is required to confer cap-independent initiation. Bicistronic constructs containing the Hsp101 mRNA 5?UTR in sense and anti-sense directions between two reporter genes were translated in both cap-independent systems. A similar bicistronic construct containing a viral internal ribosome entry site (IRES) element between the reporter genes was used as control. Internal translation of the second reporter gene was observed when the Hsp101 5?UTR was in the sense but not in the anti-sense orientation in the bicistronic construct. Taken together, these data suggest that the 5?UTR of maize Hsp101, a plant cellular mRNA, functions as an IRES-like element accounting for its cap-independent translation during heat stress. © 2005 Blackwell Publishing Ltd.
Filiaciones:
Dinkova T.D.:
Departamento de Bioquímica, Facultad de Química, Univ. Nac. Auton. de México, 04510, México DF, Mexico
Zepeda H.:
Departamento de Bioquímica, Facultad de Química, Univ. Nac. Auton. de México, 04510, México DF, Mexico
Martínez-Salas E.:
Ctro. de Biol. Molecular SO, CSIC-UAM, Cantoblanco, 28049, Madrid, Spain
Martínez L.M.:
Depto. de Biol. Molecular de Plantas, Instituto de Biotecnología, Univ. Nac. Auton. de México, Cuernavaca, Mor. 62250, Mexico
Nieto-Sotelo J.:
Depto. de Biol. Molecular de Plantas, Instituto de Biotecnología, Univ. Nac. Auton. de México, Cuernavaca, Mor. 62250, Mexico
Sánchez De Jiménez E.:
Departamento de Bioquímica, Facultad de Química, Univ. Nac. Auton. de México, 04510, México DF, Mexico
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