Biology subjects

Giaever, G.

Publications and source records attributed to Giaever, G..

5 recordsLinked to original sources

bioRxiv2026

Defining the spectrum of cellular protection against cadmium stress by Dsup expressed in yeast

The intrinsically disordered tardigrade Dsup protein has garnered attention for its ability to protect cells and organisms from radiation and oxidative stress. Our lab has previously described Dsups protective effect in yeast, finding that, while Dsup expression comes with a fitness cost, it improves survival under many stressors, including the heavy metal cadmium. While Dsups protection against oxidative stress and radiation is well-established, the mechanism by which it protects against other stressors is underinvestigated. To address this knowledge gap, we screened a collection of 4000 yeast deletion mutants expressing Dsup in the presence of three doses of cadmium to identify synergistic/synthetically lethal genes and processes. We find that Dsup broadly buffers many processes/genes at lower levels of cadmium stress but at higher doses, cells shift to buffering specific genes/processes. These results identify host genetic processes that influence Dsups ability to confer cadmium resistance to organisms.

genomics↗

bioRxiv2025

Friend and Foe: Genome-Wide Analysis of the Tardigrade Dsup Protein Expressed in Yeast Reveals Trade-offs of DNA Protection

Tardigrades are among the most resilient eukaryotes known, capable of surviving a wide range of extreme conditions. While their genomes contain thousands of tardigrade-specific genes, one key contributor to their stress resistance is the Damage suppressor (Dsup) protein. Previous work showed that expression of Dsup in cancer cells reduced DNA damage caused by X-rays. This observation has sparked growing interest in Dsup across diverse model organisms. Most studies to date have focused on phenotypic outcomes, while the mechanisms and consequences of Dsup remain poorly understood. Deciphering its mechanism is crucial, especially because Dsup expression is deleterious to some cells and organisms. In this work, we show that Dsup protects yeast against a variety of DNA-damaging agents. However, this protection is not universal, and it has a fitness cost. Analysis of nucleosome occupancy of cells expressing Dsup shows that effects on chromatin are modest, without global remodeling, and transcriptome analysis reveals a robust induction of oxidative stress pathways, which might be a form of preconditioning for oxidative stress. Genome-wide screens of [~]4300 loss-of-function mutants expressing Dsup shows that deletions incompatible with Dsup are highly enriched for DNA repair processes and that under DNA damage stress, Dsup can protect some mutants in a pathway-specific manner. Our findings demonstrate that while Dsup broadly enhances resistance to genotoxic stress, it also imposes physiological costs and generates new dependencies on DNA repair and genome maintenance pathways.

genomics↗

bioRxiv2022

Persistent acetylation of newly synthesized histones inhibits DNA replication origin activity

In Saccharomyces cerevisiae, newly synthesized histone H3 are acetylated on lysine 56 (H3 K56ac) by the Rtt109 acetyltransferase prior to their deposition on nascent DNA behind replication forks. Two deacetylases of the sirtuin family, Hst3 and Hst4, remove H3 K56ac from chromatin following S phase. hst3{Delta} hst4{Delta} cells present constitutive H3 K56ac, which sensitizes cells to replicative stress via mechanisms that remain unclear. We performed a screen to identify genes that influence cell fitness upon nicotinamide (NAM)-induced inhibition of sirtuins. The screen revealed that DBF4 heterozygosity causes NAM sensitivity. DBF4 and CDC7 encode subunits of the Dbf4-dependent kinase, which activates origins of DNA replication. We show that i) cells harboring the dbf4-1 or cdc7-4 hypomorphic alleles are sensitive to NAM, ii) Rif1, an inhibitor of Cdc7-dependent activation of origins, causes DNA damage and replication defects in NAM-treated cells and hst3{Delta} hst4{Delta} mutants, and iii) cdc7-4 hst3{Delta} hst4{Delta} cells display synthetic temperature sensitivity associated with delayed initiation of DNA replication. Such replication defects are not due to activation of the intra-S phase checkpoint but require Rtt109-dependent H3 K56ac. Overall, these results suggest that persistent H3 K56ac sensitizes cells to replicative stress in part by negatively influencing replication origin activity.

molecular biology↗

bioRxiv2021

Combining chemogenomic and gene-dose assays to investigate drug synergy

From the earliest days of using natural remedies to modern applications of clinically tested medications, combining therapies for disease treatment has been standard practice. Combination treatments can exhibit synergistic effects, broadly defined as a greater-than-additive effect of two or more therapeutic agents. Indeed, clinicians often use their experience and expertise to tailor such combinations in the hopes of maximizing the therapeutic effect. Alongside these efforts, computational studies into understanding and predicting the biophysical underpinnings of how synergy is achieved have benefitted from high-throughput screening and computational biology. One challenge is how to best design and analyze the results of synergy studies performed at scale, especially because the number of possible combinations to test quickly becomes unmanageable, and the tools to analyze the resulting data are quite new. Nevertheless, the benefits of such studies are clear -- by combining multiple drugs in the treatment of infectious disease and cancer, for instance, one can lessen host toxicity and simultaneously reduce the likelihood of resistance to treatment. In this study, we extend the widely validated chemogenomic HIPHOP assay to drug combinations. We identify a class of "combination-specific sensitive strains" that suggest mechanisms for the synergies we observe and further suggest focused follow-up studies.

genomics↗

bioRxiv2019

Broad-Spectrum Antifungal Activities and Mechanism of Drimane Sesquiterpenoids

Eight drimane sesquiterpenoids including (-)-drimenol and (+)-albicanol were synthesized from (+)-sclareolide and evaluated for their antifungal activities. Three compounds, (-)-drimenol, (+)-albicanol, and (1R,2R,4aS,8aS)-2-hydroxy-2,5,5,8a-tetramethyl-decahydronaphthalene-1-carbaldehyde (4) showed strong activity against C. albicans. (-)-Drimenol, the strongest inhibitor of the three, (at concentrations of 8 - 64 g/ml, causing 100% death of fungi), acts not only against C. albicans as a fungicidal manner, but also inhibits other fungi such as Aspergillus, Cryptococcus, Pneumocystis, Blastomyces, Fusarium, Rhizopus, Saksenaea and FLU resistant strains of C. albicans, C. glabrata, C. krusei, C. parapsilosis and C. auris. These observations suggest drimenol is a broad-spectrum antifungal agent. At high concentration (100 g/ml), drimenol caused a rupture of the fungal cell wall/membrane. In a nematode model of C. albicans infection, drimenol rescued the worms from C. albicans-mediated death, indicating drimenol is tolerable and bioactive in a metazoan. Genome-wide fitness profiling assays of both S. cerevisiae (nonessential homozygous and essential heterozygous) and C. albicans (Tn-insertion mutants) collections revealed putative genes and pathways affected by drimenol. Using a C. albicans mutants spot assay, the Crk1 kinase associated gene products, Ret2, Cdc37, and novel putative targets orf19.759, orf19.1672, and orf19.4382 were revealed to be the potential targets of drimenol. Further, computational modeling results suggest possible modification of the structure of drimenol including the A ring for improving antifungal activity.

microbiology↗