Biology subjects

Feuerbach, F.

Publications and source records attributed to Feuerbach, F..

3 recordsLinked to original sources

bioRxiv2023

Deadenylation rate is not a major determinant of RNA degradation in yeast

Gene expression and its regulation depend on mRNA degradation. In eukaryotes, degradation is controlled by deadenylation rates, since a short poly(A) tail is considered to be the signal that activates decapping and triggers mRNA degradation. In contrast to this view, we show that global stability of mRNAs can be explained by variations in decapping speed alone. Rapid decapping of unstable mRNAs, for example, allows little time for deadenylation, which explains their longer than average poly(A) tails. As predicted by modeling of RNA degradation kinetics, mRNA stabilization in the absence of decapping led to a decrease in the length of the poly(A) tail, while depletion of deadenylases only increased the tail length. Our results suggest that decapping activation dictates mRNA stability independent of the deadenylation speed. One-Sentence SummaryUnstable mRNAs are characterized by rapid 5 cap removal, independent of a prior shortening of the poly(A) tail.

molecular biology↗

bioRxiv2019

Start codon context controls translation initiation in the fungal kingdom

Eukaryotic protein synthesis initiates at a start codon defined by an AUG and its surrounding Kozak sequence context, but studies of S. cerevisiae suggest this context is of little importance in fungi. We tested this concept in two pathogenic Cryptococcus species by genome-wide mapping of translation and of mRNA 5 and 3 ends. We observed that upstream open reading frames (uORFs) are a major contributor to translation repression, that uORF use depends on the Kozak sequence context of its start codon, and that uORFs with strong contexts promote nonsense-mediated mRNA decay. Numerous Cryptococcus mRNAs encode predicted dual-localized proteins, including many aminoacyl-tRNA synthetases, in which a leaky AUG start codon is followed by a strong Kozak context in-frame AUG, separated by mitochondrial-targeting sequence. Further analysis shows that such dual-localization is also predicted to be common in Neurospora crassa. Kozak-controlled regulation is correlated with insertions in translational initiation factors in fidelity-determining regions that contact the initiator tRNA. Thus, start codon context is a signal that programs the expression and structures of proteins in fungi.

genomics↗

bioRxiv2018

General Regulatory Factors control the fidelity of transcription by restricting non-coding and ectopic initiation

The fidelity of transcription initiation is essential for accurate gene expression, but the determinants of start site selection are not fully understood. Rap1 and other General Regulatory Factors (GRFs) control the expression of many genes in yeast. We show that depletion of these factors induces widespread ectopic transcription initiation within promoters. This generates many novel non-coding RNAs and transcript isoforms with diverse stability, profoundly altering the coding potential of the transcriptome. Ectopic transcription initiation strongly correlates with altered nucleosome positioning. We show that Rap1 sterically constrains nucleosomes as its mere binding to the DNA can be sufficient for restoration normal nucleosome positioning, transcription initiation and gene expression. These results demonstrate an essential role for GRFs in the fidelity of transcription initiation and in the suppression of pervasive transcription, redefining current models of their function. They have general implications for the mechanism of transcription initiation and the control of gene expression.\n\nHIGHLIGHTSO_LIRap1, Abf1 and Reb1 control the fidelity of transcription initiation and suppress pervasive transcription\nC_LIO_LIWidespread ectopic transcription initiation in Rap1-deficient cells induces variegated alterations in gene expression\nC_LIO_LIAltered nucleosome positioning in GRFs-defective cells correlate with ectopic transcription initiation.\nC_LIO_LIRap1 controls nucleosomes positioning and transcription initiation at least partially by a steric hindrance mechanism\nC_LI

genomics↗