title: Functional and structural analysis of maize hsp101 IRES.
abstract: Maize heat shock protein of 101 KDa (HSP101) is essential for thermotolerance induction in this plant. The mRNA encoding this protein harbors an IRES element in the 5'UTR that mediates cap-independent translation initiation. In the current work it is demonstrated that hsp101 IRES comprises the entire 5'UTR sequence (150 nts), since deletion of 17 nucleotides from the 5' end decreased translation efficiency by 87% compared to the control sequence. RNA structure analysis of maize hsp101 IRES revealed the presence of three stem-loops toward its 5' end, whereas the remainder sequence contains a great proportion of unpaired nucleotides. Furthermore, HSP90 protein was identified by mass spectrometry as the protein preferentially associated with the maize hsp101 IRES. In addition, it has been found that eIFiso4G rather than eIF4G initiation factor mediates translation of the maize hsp101 mRNA.
authors.affiliation: Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, México DF, México.
authors.forename: Augusto Samuel
authors.initials: AS
authors.lastname: Jiménez-González
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas -Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Noemí
authors.initials: N
authors.lastname: Fernández
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas -Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Encarnación
authors.initials: E
authors.lastname: Martínez-Salas
authors.affiliation: Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, México DF, México.
authors.forename: Estela
authors.initials: E
authors.lastname: Sánchez de Jiménez
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
chemical_list: D020121:5' Untranslated Regions; C115569:HSP101 protein, plant; D018841:HSP90 Heat-Shock Proteins; D010940:Plant Proteins; D014157:Transcription Factors