Research, Research Articles
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 Rallis3,4, Jürg Bähler3,4 and Sara E. Mole1,2,3
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. Bisschops1,3,#, Tim Vos1,#, Rubén Martínez-Moreno2,4, 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. Piatkov1,3,#, Tri T. M. Vu1,#, 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...
A single mutation in the 15S rRNA gene confers non sense suppressor activity and interacts with mRF1 the release factor in yeast mitochondria
Ali Gargouri, Catherine Macadré and Jaga Lazowska
This article presents the nucleotide sequence of the mim3-1 mitochondrial ribosomal suppressor, acting on ochre mitochondrial mutations and one frameshift mutation in Saccharomyces cerevisiae. A hypothetical mechanism of suppression by "ribosome shifting" is also discussed in view of the nature of mutations suppressed and not suppressed.
The lysosomotropic drug LeuLeu-OMe induces lysosome disruption and autophagy-independent cell death in Trypanosoma brucei
Hazel Xinyu Koh1,2, Htay Mon Aye1, Kevin S. W. Tan2 and Cynthia Y. He1
Trypanosoma brucei is a blood-borne, protozoan parasite that causes African sleeping sickness in humans and nagana in animals. The current chemotherapy relies on only a handful of drugs that display undesirable toxicity, poor efficacy and drug-resistance. In this study, we explored the use of lysosomotropic drugs to induce bloodstream form T. brucei cell death via lysosome destabilization. We measured drug concentrations that inhibit cell proliferation by 50% (IC50) for several compounds, chosen based on their lysosomotropic effects previously reported in Plasmodium falciparum. The lysosomal effects and cell death induced by L-leucyl-L-leucyl methyl ester (LeuLeu-OMe) were further analyzed by flow cytometry and immunofluorescence analyses of different lysosomal markers...
Farnesol inhibits translation to limit growth and filamentation in C. albicans and S. cerevisiae
September 4, 2017
Farnesol, a quorum-sensing molecule, inhibits the switch from yeast to filamentous growth in Candida albicans by impeding translation initiation, differing from fusel alcohols that affect the initiation factor eIF2B, as it disrupts mRNA interaction with the ribosome and prevents preinitiation complex formation.
Cristae architecture is determined by an interplay of the MICOS complex and the F1FO ATP synthase via Mic27 and Mic10
July 20, 2017
This article investigates the roles of MICOS subunits Mic27 and Mic10, revealing their antagonistic and cooperative interactions in crista junction formation and cristae membrane curvature, and proposes a model where F1FO-ATP synthase is connected to MICOS, influencing CJ formation.
Integrative modules for efficient genome engineering in yeast
June 5, 2017
The study introduces a set of vectors with integrative modules designed for effective genome integration into standard marker loci of Saccharomyces cerevisiae, enabling precise expression levels using various promoters and demonstrating the capability of stable multi-gene integration, which is useful for tasks like multi-color cellular imaging and metabolic engineering.
Thiol trapping and metabolic redistribution of sulfur metabolites enable cells to overcome cysteine overload
March 27, 2017
In this study, researchers investigate the mechanisms for handling cysteine overload using Saccharomyces cerevisiae, finding that overexpressing the high affinity cysteine transporter, YCT1, enables yeast cells to rapidly accumulate high levels of intracellular cysteine. The study demonstrates that cells can manage potentially toxic levels of cysteine by converting it to non-reactive thiol forms and utilizing the metabolic products for cell growth.
Identification of Ftr1 and Zrt1 as iron and zinc micronutrient transceptors for activation of the PKA pathway in Saccharomyces cerevisiae
March 2, 2017
We now show that the yeast high-affinity iron transporter Ftr1 and high-affinity zinc transporter Zrt1 function as transceptors for the micronutrients iron and zinc. We show that replenishment of iron to iron-starved cells or zinc to zinc-starved cells triggers within 1-2 minutes a rapid surge in trehalase activity, a well-established PKA target.
Balanced CoQ6 biosynthesis is required for lifespan and mitophagy in yeast
February 3, 2017
In brief, we show that, in yeast, Ptc7 modulates the adaptation to respiratory metabolism by dephosphorylating Coq7 to supply newly synthesized CoQ6, and by activating mitophagy to remove defective mitochondria at stationary phase, guaranteeing a proper CLS in yeast.
Mutational analysis of fructose-1,6-bis-phosphatase FBP1 indicates partially independent functions in gluconeogenesis and sensitivity to genotoxic stress
February 1, 2017
Our results support predicted vital roles of several fructose-1,6-bisphosphatase residues for enzymatic activity and led to the identification of residues indispensable for the MMS-sensitizing effect. Despite an overlap between these two properties, careful analysis revealed two mutations, Asn75 and His324, which decouple the enzymatic activity and the MMS-sensitizing effect, indicating two distinctive biological activities linked in this key gluconeogenesis enzyme.
The copper transport-associated protein Ctr4 can form prion-like epigenetic determinants in Schizosaccharomyces pombe
January 2, 2017
Ctr4 exhibits multiple features diagnostic of other fungal prions and is the first example of a prion in fission yeast. These findings suggest that transmissible protein-based determinants of traits may be more widespread among fungi.
Improvement of biochemical methods of polyP quantification
December 29, 2016
As the main output of this evaluation we propose a straightforward and robust procedure that can be used as gold standard protocol for cellular polyP purification and determination from unicellular organisms, thus providing consistency to measurements and facilitating inter-laboratory comparisons and biological interpretation of the results.
Bax mitochondrial relocation is linked to its phosphorylation and its interaction with Bcl-xL
December 5, 2016
The heterologous expression of Bax, and other Bcl-2 family members, in the yeast Saccharomyces cerevisiae, has proved to be a valuable reporter system to investigate the molecular mechanisms underlying their interaction with mitochondria. Our data provide the molecular basis for a model of dynamic equilibrium for Bax localization and activation, regulated both by phosphorylation and Bcl-xL.