Abstract
GCN4 encodes a transcriptional activator of amino acid biosynthetic genes in yeast that is regulated at the translational level. The 5′ leader of GCN4 mRNA contains four small open-reading-frames. By constructing point mutations in the initiation codons of these sequences, we show that they are essential for translational repression of GCN4. Each upstream AUG codon can repress translation; however, the two 3′ proximal AUG codons are much more inhibitory than the 5′ proximal AUG codons. Unexpectedly, the first AUG codon is required for efficient GCN4 expression under starvation conditions. This positive function appears to involve antagonism of the inhibitory effect of the 3′ proximal AUG codons since it is dispensable in the absence of these sequences. The interaction between the upstream AUG codons is modulated by the trans-acting factors GCN2 and GCD1 in response to amino acid availability.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.