Individual RNA remains a challenging signal to synthetically transduce into different types of cellular information. Here, we describe Ribozyme-ENabled Detection of RNA (RENDR), a plug-and-play strategy that uses cellular transcripts to template the assembly of split ribozymes, triggering splicing reactions that generate orthogonal protein outputs. To identify split ribozymes that require templating for splicing, we use laboratory evolution to evaluate the activities of different split variants of the Tetrahymena thermophila ribozyme. The best design delivers a 93-fold dynamic range of splicing with RENDR controlling fluorescent protein production in response to an RNA input. We further resolve a thermodynamic model to guide RENDR design, show how input signals can be transduced into diverse outputs, demonstrate portability across different bacteria, and use RENDR to detect antibiotic-resistant bacteria. This work shows how transcriptional signals can be monitored in situ and converted into different types of biochemical information using RNA synthetic biology.

Somatic missense mutations in histone genes turn these essential proteins into oncohistones, which can drive oncogenesis. Understanding how missense mutations alter histone function is challenging in mammals as mutations occur in a single histone gene. For example, described oncohistone mutations predominantly occur in the histone H3.3 gene, despite the human genome encoding fifteen H3 genes. To understand how oncogenic histone missense mutations alter histone function, we leveraged the budding yeast model, which contains only two H3 genes, to explore the functional consequences of oncohistones H3K36M, H3G34W, H3G34L, H3G34R, and H3G34V. Analysis of cells that express each of these variants as the sole copy of H3 reveals that H3K36 mutants show different drug sensitivities compared to H3G34 mutants. This finding suggests that changes to proximal amino acids in the H3 N-terminal tail alter distinct biological pathways. We exploited the caffeine sensitive growth of H3K36 mutant cells to perform a high copy suppressor screen. This screen identified genes linked to histone function and transcriptional regulation, including Esa1, a histone H4/H2A acetyltransferase; Tos4, a forkhead-associated domain-containing gene expression regulator; Pho92, an N6-methyladenosine RNA binding protein and Sgv1/Bur1, a cyclin-dependent kinase. We show that the Esa1 lysine acetyltransferase activity is critical for suppression of the caffeine sensitive growth of H3K36R mutant cells while the previously characterized binding interactions of Tos4 and Pho92 are not required for suppression. This screen identifies pathways that could be altered by oncohistone mutations and highlights the value of yeast genetics to identify pathways altered by such mutations.

Histones are critical for both packaging DNA into chromatin within the cell nucleus and for regulating all aspects of gene expression. DNA is packaged into nucleosomes, which consist of a hetero‐octamer of histones H2A, H2B, H3, and H4. Somatic missense mutations in histone genes turn these essential proteins into oncohistones, which can drive oncogenesis. These mutations, termed oncohistone mutations, have been linked to multiple types of cancer, including pediatric gliomas and head and neck cancers. In humans, a histone H3 lysine 36 to methionine missense mutation (H3K36M) causes chondroblastomas. Our lab has employed a budding yeast model system to explore how missense mutations such as H3K36M alter histone function. These studies, as well as those from previous groups, reveal that changes at H3K36 confer sensitivity to growth on plates containing caffeine, suggesting that H3K36 mutants show changes in stress response pathways. To further define these pathways, the laboratory employed a high copy suppressor screen to identify genes that when overexpressed could suppress the caffeine‐sensitive growth phenotype of H3K3M cells. This screen identified several genes linked to epigenetic regulation, including TOS4, which encodes a forkhead‐associated (FHA) domain protein that interacts with Rpd3L and Set3 histone deacetylase complexes. To begin to define the function of Tos4 required for this suppression, two amino acid substitutions within the Tos4 FHA domain that disrupt interaction with histone deacetylase complexes (R122A, N161A) were generated. This Tos4 variant still suppresses the caffeine‐sensitive growth of H3K36M cells, suggesting these interactions are not required for suppression. My studies focus on defining the function of Tos4 required for this suppression. Results from such studies may provide insight for novel therapeutic targets in humans diagnosed with these distinct oncohistone‐driven cancer types.

Somatic missense mutations in histone genes turn these essential proteins into oncohistones, which can drive oncogenesis. Understanding how missense mutations alter histone function is challenging in mammals as the changes occur in a single histone gene. For example, described oncohistone mutations predominantly occur in the histone H3.3 gene, despite the human genome encoding 15 H3 genes. To understand how oncogenic histone missense mutations alter histone function, we leverage the budding yeast model, which encodes only two H3 genes, to explore the functional consequences of oncohistones H3K36M, H3G34W, H3G34L, H3G34R, and H3G34V. An analysis of cells that express each of these variants as the sole copy of H3 reveals that H3K36-mutants show different drug sensitivities compared to H3G34 mutants. This finding suggests that changes to proximal amino acids in the H3 N-terminal tail alter distinct biological pathways. We exploited the caffeine sensitive growth of H3K36 mutant cells to perform a high copy suppressor screen. This screen identified genes linked to histone function and transcriptional regulation, the histone H4/H2A acetyltransferase, Esa1, a forkhead-associated domain-containing gene expression regulator, Tos4, an m6A RNA binding protein, Pho92, and a cyclin-dependent kinase, Sgv1/Bur1. We show that the Esa1 lysine acetyltransferase activity is critical for suppression of the caffeine sensitive growth of H3K36R mutant cells while neither of the characterized binding interactions of Tos4 nor Pho92 are required for suppression. Finally, Sgv1/Bur1-mediated suppression may occur through a dominant negative mechanism. This screen identifies pathways that could be altered by oncohistone mutations and highlights the value of yeast genetics to identify pathways altered by such mutations.