Biology subjects

Sutter, B. M.

Publications and source records attributed to Sutter, B. M..

5 recordsLinked to original sources

bioRxiv2026

Metabolic stress reveals widespread accumulation of cap-unmethylated RNAs

RNA polymerase II transcripts are capped with N7-methylguanosine (mG), a conserved modification essential for mRNA function. Although traditionally viewed as constitutive, we developed a mass spectrometry-based method to demonstrate that in both yeast and mammalian cells, a substantial population of mRNAs lack cap methylation in response to SAM-limiting conditions and oxidative stress, which may be frequently encountered across organisms. Through developing two transcriptome-wide approaches, we found that methylation is enriched on specific transcripts and uncovered an unexpected connection between histone H3K36me3 and cap methylation, with both marks preferentially associated with stress-responsive MAPK signaling pathways. Strikingly, cap-unmethylated mRNAs exhibit features of canonical mRNAs--they are polyadenylated, exported to the cytosol, and translated. Enforced cap methylation reduces cell growth under SAM limitation, suggesting that unmethylated mRNAs confer an adaptive advantage during stress. These findings establish mRNA cap methylation as a dynamic, regulated modification and a previously underappreciated layer of gene expression control.

cell biology↗

bioRxiv2026

The promoter-poised Rpd3 HDAC complex orchestrates global chromatin reprogramming upon nutrient transition

Adaptive transcriptional rewiring underlies the metabolic flexibility of Saccharomyces cerevisiae. We demonstrate that the histone deacetylase Rpd3 mediates nutrient-dependent chromatin reprogramming that coordinates transcriptional shutdown and global acetylation balance during metabolic transitions. Genome-wide analyses reveal that Rpd3 complexes drive rapid, reversible histone deacetylation across promoters and gene bodies, fine-tuning transcriptional output. Rpd3, primarily through the large complex (Rpd3L), localizes at promoters of active genes enriched in H3K9ac and the acetyltransferase Gcn5. Upon nutrient shift, Gcn5 disengages while Rpd3-mediated H3K9 deacetylation enforces repression. Loss of Rpd3 or its Rpd3L-specific subunit, Pho23, disrupts this balance, resulting in the aberrant persistence of growth programs upon starvation and defective activation of respiratory genes in the presence of glucose. HDACs thus can act as metabolic gatekeepers, coupling nutrient cues to chromatin reprogramming and ensuring transcriptional fidelity during metabolic transitions, thereby resolving the long-standing paradox of HDAC enrichment at active promoters.

biochemistry↗

bioRxiv2023

Exonuclease Xrn1 regulates TORC1 signaling in response to SAM availability

Autophagy is a conserved process of cellular self-digestion that promotes survival during nutrient stress. In yeast, methionine starvation is sufficient to induce autophagy. One pathway of autophagy induction is governed by the SEACIT complex, which regulates TORC1 activity in response to amino acids through the Rag GTPases Gtr1 and Gtr2. However, the precise mechanism by which SEACIT senses amino acids and regulates TORC1 signaling remains incompletely understood. Here, we identify the conserved 5-3 RNA exonuclease Xrn1 as a surprising and novel regulator of TORC1 activity in response to methionine starvation. This role of Xrn1 is dependent on its catalytic activity, but not on degradation of any specific class of mRNAs. Instead, Xrn1 modulates the nucleotide-binding state of the Gtr1/2 complex, which is critical for its interaction with and activation of TORC1. This work identifies a critical role for Xrn1 in nutrient sensing and growth control that extends beyond its canonical housekeeping function in RNA degradation and indicates an avenue for RNA metabolism to function in amino acid signaling into TORC1.

cell biology↗

bioRxiv2022

Pbp1 stabilizes and promotes the translation of Puf3-target mRNAs involved in mitochondrial biogenesis

Pbp1 (poly(A)-binding protein - binding protein 1) is a cytoplasmic stress granule marker that is capable of forming condensates that function in the negative regulation of TORC1 signaling under respiratory conditions. How mutations in its mammalian ortholog ataxin-2 are linked to neurodegenerative conditions remains unclear. Here, we show that loss of Pbp1 leads to decreases in amounts of mitochondrial proteins whose encoding mRNAs are targets of Puf3, a member of the PUF (Pumilio and FBF) family of RNA-binding proteins. We found that Pbp1 stabilizes and promotes the translation of Puf3-target mRNAs in respiratory conditions, such as those involved in the assembly of cytochrome c oxidase. We further show that Pbp1 and Puf3 interact through their respective low complexity domains, which is required for Puf3-target mRNA stabilization and translation. Our findings reveal a key role for Pbp1-containing assemblies in enabling the translation of mRNAs critical for mitochondrial biogenesis and respiration. They may further begin to explain prior associations of Pbp1/ataxin-2 with RNA, stress granule biology, mitochondrial function, and neuronal health.

cell biology↗

bioRxiv2021

The SCFMet30 ubiquitin ligase senses cellular redox state to regulate the transcription of sulfur metabolism genes

In yeast, control of sulfur amino acid metabolism relies upon Met4, a transcription factor which activates the expression of a network of enzymes responsible for the biosynthesis of cysteine and methionine. In times of sulfur abundance, the activity of Met4 is repressed via ubiquitination by the SCFMet30 E3 ubiquitin ligase, but the mechanism by which the F-box protein Met30 senses sulfur status to tune its E3 ligase activity remains unresolved. Herein, we show that Met30 responds to flux through the transsulfuration pathway to regulate the MET gene transcriptional program. In particular, Met30 is responsive to the biological gas hydrogen sulfide, which is sufficient to induce ubiquitination of Met4 in vivo. Additionally, we identify important cysteine residues in Met30s WD-40 repeat region that sense the availability of sulfur in the cell. Our findings reveal how SCFMet30 dynamically senses the flow of sulfur metabolites through the transsulfuration pathway to regulate synthesis of these special amino acids.

biochemistry↗