Research – Page 9 – Microbial Cell

Research Articles

Inhibition of Aβ₄₂ oligomerization in yeast by a PICALM ortholog and certain FDA approved drugs

Sei-Kyoung Park¹, Kiira Ratia², Mariam Ba¹, Maria Valencik¹ and Susan W. Liebman^1,3

The formation of small Aβ42 oligomers has been implicated as a toxic species in Alzheimer disease (AD). Here, we show that the mechanism of the PICALM, human AD risk factor, is likely to reduce the level of Aβ42 oligomers in cells. We screened FDA-approved drugs to identify candidates that prevent the formation of Aβ42 small oligomers using the yeast Aβ42-RF reporter system. We also showed that each of the drug hits counteract yeast and mammalian cell toxicity associated with Aβ42 small aggregates.

Global translational impacts of the loss of the tRNA modification t⁶A in yeast

Patrick C. Thiaville^1,2,3,4, Rachel Legendre⁴, Diego Rojas-Benítez⁵, Agnès Baudin-Baillieu⁴, Isabelle Hatin⁴, Guilhem Chalancon⁶, Alvaro Glavic⁵, Olivier Namy⁴, Valérie de Crécy-Lagard^1,3

The universal tRNA modification t6A is found at position 37 of nearly all tRNAs decoding ANN codons. Analysis of codon occupancy rates suggests that one of the major roles of t6A is to homogenize the process of elongation by slowing the elongation rate at codons decoded by high abundance tRNAs and I34:C3 pairs while increasing the elongation rate of rare tRNAs and G34:U3 pairs. This work reveals that the consequences of t6A absence are complex and multilayered and has set the stage to elucidate the molecular basis of the observed phenotypes.

Ergosterone-coupled Triazol molecules trigger mitochondrial dysfunction, oxidative stress, and acidocalcisomal Ca²⁺ release in Leishmania mexicana promastigotes

Figarella K¹, Marsiccobetre S¹, Arocha I¹, Colina W², Hasegawa M^2,†, Rodriguez M², Rodriguez-Acosta A³, Duszenko M⁴, Benaim G⁵, Uzcategui NL³

The protozoan parasite Leishmania causes a variety of sicknesses with different clinical manifestations known as leishmaniasis. Investigations looking for new targets or new active molecules focus mainly on the disruption of parasite specific pathways. In this sense, ergosterol biosynthesis is one of the most attractive because it does not occur in mammals. Our results indicate that ergosterone-triazol coupled molecules induce a regulated cell death process in the parasite and may represent starting point molecules in the search of new chemotherapeutic agents to combat leishmaniasis.

INO1 transcriptional memory leads to DNA zip code-dependent interchromosomal clustering

Donna Garvey Brickner, Robert Coukos and Jason H. Brickner

Many genes localize at the nuclear periphery through physical interaction with the nuclear pore complex (NPC). We have found that the yeast INO1 gene is targeted to the NPC both upon activation and for several generations after repression, a phenomenon called epigenetic transcriptional memory. Targeting of INO1 to the NPC requires distinct cis-acting promoter DNA zip codes under activating conditions and under memory conditions. When at the nuclear periphery, active INO1 clusters with itself and with other genes that share the GRS I zip code. Here, we show that during memory, the two alleles of INO1 cluster in diploids and endogenous INO1 clusters with an ectopic INO1 in haploids. After repression, INO1 does not cluster with GRS I - containing genes. Furthermore, clustering during memory requires Nup100 and two sets of DNA zip codes...

A central role for TOR signalling in a yeast model for juvenile CLN3 disease

Michael E. Bond¹, Rachel Brown¹, Charalampos Rallis^3,4, Jürg Bähler^3,4 and Sara E. Mole^1,2,3

Yeasts provide an excellent genetically tractable eukaryotic system for investigating the function of genes in their biological context, and are especially relevant for those conserved genes that cause disease. Bond et al. study the role of btn1, the orthologue of a human gene that underlies an early onset neurodegenerative disease (juvenile CLN3 disease, neuronal ceroid lipofuscinosis (NCLs) or Batten disease) in the fission yeast Schizosaccharomyces pombe.

Oxygen availability strongly affects chronological lifespan and thermotolerance in batch cultures of Saccharomyces cerevisiae

Markus M.M. Bisschops^1,3,#, Tim Vos^1,#, Rubén Martínez-Moreno^2,4, Pilar de la Torre Cortés¹, Jack T. Pronk¹, Pascale Daran-Lapujade¹

Stationary-phase (SP) batch cultures of Saccharomyces cerevisiae, in which growth has been arrested by carbon-source depletion, are widely applied to study chronological lifespan, quiescence and SP-associated robustness. Based on this type of experiments, typically performed under aerobic conditions, several roles of oxygen in aging have been proposed. However, SP in anaerobic yeast cultures has not been investigated in detail. Here, we use the unique capability of S. cerevisiae to grow in the complete absence of oxygen to directly compare SP in aerobic and anaerobic bioreactor cultures. This comparison revealed strong positive effects of oxygen availability on adenylate energy charge, longevity and thermotolerance during SP. A low thermotolerance of...

DNA damage checkpoint adaptation genes are required for division of cells harbouring eroded telomeres

Sofiane Y. Mersaoui, Serge Gravel, Victor Karpov, and Raymund J. Wellinger

In budding yeast, telomerase and the Cdc13p protein are two key players acting to ensure telomere stability. This article shows that while the capping process can be flexible, it takes a very specific genetic setup to allow a change from canonical capping to alternative capping.

The MAPKKKs Ste11 and Bck1 jointly transduce the high oxidative stress signal through the cell wall integrity MAP kinase pathway

Chunyan Jin^#, Stephen K. Kim, Stephen D. Willis and Katrina F. Cooper

Oxidative stress stimulates the Rho1 GTPase, which in turn induces the cell wall integrity (CWI) MAP kinase cascade. CWI activation promotes stress-responsive gene expression through activation of transcription factors (Rlm1, SBF) and nuclear release and subsequent destruction of the repressor cyclin C. This study reports that, in response to high hydrogen peroxide exposure, or in the presence of constitutively active Rho1, cyclin C still translocates to the cytoplasm and is degraded in cells lacking Bck1, the MAPKKK of the CWI pathway.

Formyl-methionine as a degradation signal at the N-termini of bacterial proteins

Konstantin I. Piatkov^1,3,#, Tri T. M. Vu^1,#, Cheol-Sang Hwang² and Alexander Varshavsky¹

Varshavsky and colleagues solve a long-standing mystery in proteolysis! In bacteria, all nascent proteins bear the pretranslationally formed N-terminal formyl-methionine (fMet) residue. The fMet residue is cotranslationally deformylated by a ribosome-associated deformylase. The formylation of N-terminal Met in bacterial proteins is not strictly essential for either translation or cell viability. Moreover, protein synthesis by the cytosolic ribosomes of eukaryotes does not involve the formylation of N-terminal Met. What, then, is the main biological function of this metabolically costly, transient, and not strictly essential modification of N‑terminal Met, and why has Met formylation not been eliminated during bacterial evolution? One possibility is that the similarity of the formyl and acetyl groups, their identical locations in...

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Chromosome-condensed G1 phase yeast cells are tolerant to desiccation stress

November 26, 2021

The budding yeast Saccharomyces cerevisiae is capable of surviving extreme water loss for a long time. However, less is known about the mechanism of its desiccation tolerance. In this study, we revealed that in an exponential culture, all desiccation tolerant yeast cells were in G1 phase and had condensed chromosomes. (...)

Detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its first variants in fourplex real-time quantitative reverse transcription-PCR assays

November 25, 2021

The early diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections is required to identify and isolate contagious patients to prevent further transmission of SARS-CoV-2. In this study, we present a multitarget real-time TaqMan reverse transcription PCR (rRT-PCR) assay for the quantitative detection of SARS-CoV-2 and some of its circulating variants harboring mutations that give the virus a selective advantage. Seven different primer-probe sets that included probes containing locked nucleic acid (LNA) nucleotides were designed to amplify specific wild-type and mutant sequences in Orf1ab, Envelope (E), Spike (S), and Nucleocapsid (N) genes (...)

Forced association of SARS-CoV-2 proteins with the yeast proteome perturb vesicle trafficking

October 27, 2021

This work demonstrates that the yeast Synthetic Physical Interactions method is a rapid way to identify potential functions of ectopic viral proteins.

Airborne bacteria in show caves from Southern Spain

July 26, 2021

This study analyzes the factors conditioning the diversity of airborne bacteria recorded in three Andalusian show caves, subjected to different managements.

Landscapes and bacterial signatures of mucosa-associated intestinal microbiota in Chilean and Spanish patients with inflammatory bowel disease

June 18, 2021

This study investigates the landscapes and alterations of mucosa-associated intestinal microbiota in patients with inflammatory bowel diseases, which cause chronic inflammation of the gut, including ulcerative colitis and Crohn’s disease.

Genome, transcriptome and secretome analyses of the antagonistic, yeast-like fungus Aureobasidium pullulans to identify potential biocontrol genes

June 8, 2021

This study highlights the value of a sequential approach starting with genome mining and consecutive transcriptome and secretome analyses in order to identify a limited number of potential target genes for detailed, functional analyses in Aureobasidium pullulans.

Barcode sequencing and a high-throughput assay for chronological lifespan uncover ageing-associated genes in fission yeast

May 10, 2021

This work presents two approaches to study chronological lifespan (CLS) for medium- to high-throughput applications, a method for Bar-seq to identify mutants showing altered CLS and a novel medium-throughput colony-forming units assay that can be largely automated by robotics.