Open AccessEvidence for regulation of reinitiation in translational control of GCN4 mRNA.
Author(s) -
Alan G. Hinnebusch,
Belinda M. Jackson,
Peter P. Mueller
Publication year - 1988
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.85.19.7279
Subject(s) - translation (biology) , messenger rna , microbiology and biotechnology , open reading frame , biology , gene , genetics , peptide sequence
Translational control of the GCN4 gene of Saccharomyces cerevisiae is mediated by four upstream open reading frames (URFs) present in the leader of GCN4 mRNA. URFs 3 and 4 efficiently repress GCN4 expression in normal growth conditions; URFs 1 and 2 are required to overcome this repression in amino acid-starved cells. lacZ fusions to URFs 3 and 4 were used to determine the translational event that is regulated at these sequences by URFs 1 and 2. URF3-lacZ, URF4-lacZ, and GCN4-lacZ fusions are affected similarly by URFs 1 and 2 when no other URFs are present in the leader: expression from all three fusions is reduced by an amount slightly greater in repressing than in derepressing conditions. These results are inconsistent with models that postulate a differential effect of URFs 1 and 2 on initiation or elongation rates at URFs 3 and 4 versus the GCN4 coding sequences. We propose that the efficiency of reinitiation at the GCN4 AUG codon after translation of URFs 3 and 4 is the translational event that is stimulated in derepressing conditions by URFs 1 and 2.