Vol. 03, 2016
Mek1/Mre4 is a master regulator of meiotic recombination in budding yeast
Nancy M. Hollingsworth
This article comments on work published by Chen et al. (PLoS BIol, 2015), showing that the meiosis specific kinase Mek1 indirectly regulates the crossover/non-crossover decision between homologs as well as genetic interference and suggests Mek1 to be a "master regulator" of meiotic recombination in budding yeast.
Shaping meiotic chromosomes with SUMO: a feedback loop controls the assembly of the synaptonemal complex in budding yeast
Hideo Tsubouchi1, Bilge Argunhan1 and Tomomi Tsubouchi2
This article comments on work published by Leung et al. (J Cell Biol, 2015), which shows that the formation of the meiosis-specific synaptonemal complex is controlled through SUMOylation of a regulator required for the assembly of transverse filaments, implicating the involvement of a positive feedback loop in the control of synaptonemal complex assembly.
Towards understanding the gliotoxin detoxification mechanism: in vivo thiomethylation protects yeast from gliotoxin cytotoxicity
Elizabeth B. Smith, Stephen K. Dolan, David A. Fitzpatrick, Sean Doyle and Gary W. Jones
Gliotoxin is a mycotoxin produced by some species of ascomycete fungi including the opportunistic human pathogen Aspergillus fumigatus. In order to produce gliotoxin the host organism needs to have evolved a self-protection mechanism. The authors demonstrate that the activity of a novel thiomethyltransferase is requiered for protection against exogenous gliotoxin and provide implications for understanding the evolution of gliotoxin self-protection mechanisms.
Mitochondrial proteomics of the acetic acid – induced programmed cell death response in a highly tolerant Zygosaccharomyces bailii – derived hybrid strain
Joana F Guerreiro1, Belém Sampaio-Marques2,3, Renata Soares4, Ana Varela Coelho4, Cecília Leão2,3, Paula Ludovico2,3, Isabel Sá-Correia1
Very high concentrations of acetic acid at low pH induce programmed cell death (PCD) in both the experimental model Saccharomyces cerevisiae and in Zygosaccharomyces bailii, the latter being considered the most problematic acidic food spoilage yeast due to its remarkable intrinsic resistance to this food preservative. This study offers insights into the mechanisms involved in acetic acid - induced PCD in the Z. bailii-derived hybrid strain ISA1307 by analyzing the yeast mitochondrial protein expression profile of cells challenged by acetic acid.
The transcriptional repressor Sum1p counteracts Sir2p in regulation of the actin cytoskeleton, mitochondrial quality control and replicative lifespan in Saccharomyces cerevisiae
Ryo Higuchi-Sanabria1, Jason D. Vevea1,3, Joseph K. Charalel1,4, Maria L. Sapar5, Liza A. Pon1,2
Increasing the stability or dynamics of the actin cytoskeleton can extend lifespan in C. elegans and S. cerevisiae. Actin cables of budding yeast, bundles of actin filaments that mediate cargo transport, affect lifespan control through effects on mitochondrial quality control. Here, we report that Sum1p and Sir2p inversely regulate actin and mitochondrial maintenance, as well as lifespan.
Learning epigenetic regulation from mycobacteria
Sanjeev Khosla1, Garima Sharma1,2 and Imtiyaz Yaseen1,2
This article comments on work published by Koshla et al. (Nat Commun, 2015), which shows that pathogenic Mycobacterium tuberculosis has evolved strategies to hijack the epigenetic regulation of host transcripton for its own survival.
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. Liebman1,3
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.
Biofilm assembly becomes crystal clear – filamentous bacteriophage organize the Pseudomonas aeruginosa biofilm matrix into a liquid crystal
Patrick R. Secor1, Laura K. Jennings1, Lia A. Michaels1, Johanna M. Sweere2, Pradeep K. Singh1, William C. Parks3, Paul L. Bollyky2
This article comments on work published by Secor et al. (Host Cell & Microbe, 2015), which highlights a previously unknown role for filamentous Pf phage in organizing the P. aeruginosa biofilm matrix into a liquid crystalline structure. These findings help ground our understanding of biofilm formation within established paradigms of soft matter physics
Antibiotic use in childhood alters the gut microbiota and predisposes to overweight
Katri Korpela and Willem M de Vos
This article comments on work published by Korpela et al. (Nat Commun, 2016), which investigates the correlation between the use of antibiotics in early life and the excessive weight gain in later childhood.
Evidence for the hallmarks of human aging in replicatively aging yeast
Georges E. Janssens, Liesbeth M. Veenhoff
Recently, efforts have been made to characterize the hallmarks that accompany and contribute to the phenomenon of aging, as most relevant for humans. Remarkably, studying the finite lifespan of the single cell eukaryote budding yeast has been paramount for our understanding of aging. Here, we compile observations from literature over the past decades of research on replicatively aging yeast to highlight how the hallmarks of aging in humans are present in yeast.
Increased spontaneous recombination in RNase H2-deficient cells arises from multiple contiguous rNMPs and not from single rNMP residues incorporated by DNA polymerase epsilon
Anastasiya Epshtein1, Catherine J. Potenski2, and Hannah L. Klein1
Ribonucleotides (rNMPs) can become embedded in DNA from insertion by DNA polymerases, failure to remove Okazaki fragment primers, R-loops that can prime replication, and RNA/cDNA-mediated recombination. We report here that recombination is not stimulated by rNMPs incorporated by the replicative polymerase epsilon. Instead, recombination seems to be stimulated by multiple contiguous rNMPs, which may arise from R-loops or replication priming events.
Bacterial outer membrane vesicle biogenesis: a new mechanism and its implications
Sandro Roier, Franz G. Zingl, Fatih Cakar, and Stefan Schild
This article comments on work published by Roier et al. (Nat Commun, 2016), which proposes a novel and highly conserved bacterial outer membane vesicle biogenesis mechanism based on phospholipid accumulation in the outer leaflet of the outer membrane.
Construction and evaluation of yeast expression networks by database-guided predictions
Katharina Papsdorf1,#, Siyuan Sima1,#, Gerhard Richter2, Klaus Richter1
DNA-Microarrays are powerful tools to obtain expression data on the genome-wide scale. We set out to define a way to cluster microarray data according to their expressional relationship and to obtain information on the significance of this clustering approach.
Optogenetic monitoring identifies phosphatidylthreonine-regulated calcium homeostasis in Toxoplasma gondii
Arunakar Kuchipudi1, Ruben D. Arroyo-Olarte1, Friederike Hoffmann1, Volker Brinkmann2, Nishith Gupta1, 2
Toxoplasma gondii is an obligate intracellular parasite, which inflicts acute as well as chronic infections in a wide range of warm-blooded vertebrates. Using an optogenetic sensor to monitor subcellular calcium in this model intracellular pathogen we found a novel regulatory function of phosphatidylthreonine in calcium signaling.
Autophagy: machinery and regulation
Zhangyuan Yin, Clarence Pascual and Daniel J. Klionsky
Macroautophagy/autophagy is an evolutionarily conserved cellular degradation process that targets cytoplasmic materials including cytosol, macromolecules and unwanted organelles. The discovery and analysis of autophagy-related (Atg) proteins have unveiled much of the machinery of autophagosome formation. In this review, we briefly summarize the physiological roles, molecular mechanism, regulatory network, and pathophysiological roles of autophagy.
NprR, a moonlighting quorum sensor shifting from a phosphatase activity to a transcriptional activator
Stéphane Perchat1, Antoine Talagas2, Samira Zouhir2, Sandrine Poncet1, Laurent Bouillaut1,¶, Sylvie Nessler2 and Didier Lereclus1
This article comments on work published by Perchat et al. (PLoS Pathog, 2016), which demonstrates that, in the absence of the signaling peptide NprX, the sensor NprR is a dimer, which negatively controls sporulation in Bacillus thuringiensis, independently of its transcription factor activity.
Threading Granules in Freiburg: 2nd International Symposium on “One Mitochondrion, Many Diseases – Biological and Molecular Perspectives”, a FRIAS Junior Researcher Conference, Freiburg im Breisgau, Germany, March 9th/10th, 2016
Ralf J. Braun1, Ralf M. Zerbes2, Florian Steinberg3, Denis Gris4, and Verónica I. Dumit5
INTRODUCTION Mitochondria (greek: μίτος & χονδρίον, mitos & chondrion, i.e., thread & granule) are the power houses of eukaryotic cells, and are pivotally involved in essential metabolic processes, including iron/sulfur
The interaction between herpes simplex virus 1 genome and promyelocytic leukemia nuclear bodies (PML-NBs) as a hallmark of the entry in latency
Patrick Lomonte
This article comments on work published by Maroul et al. (PLoS Pathog, 2016), which demonstrates that the interaction of the viral genomes with the nuclear architecture and specifically the promyelocytic leukemia nuclear bodies is a major determinant for the entry of HSV-1 into latency.
Francisella IglG protein and the DUF4280 proteins: PAAR-like proteins in non-canonical Type VI secretion systems?
Claire Lays1, 2, Eric Tannier2, 3, Thomas Henry1,2
This article comments on work published by Rigard et al. (PLoS Pathog, 2013), which identified the function of IgIG, a protein of unknown function, encoded within the Francisella Pathogenicity Island.
B cell-helping functions of gut microbial metabolites
Chang H. Kim1,2,3,4
This article comments on work published by Kim et al. (Cell Host & Microbe, 2016), which showed that the microbial metabolites short-chain fatty acids (SCFAs) regulate the metabolism and gene expression in B cells to promote antibody production.
How do yeast sense mitochondrial dysfunction?
Dmitry A. Knorre1, Svyatoslav S. Sokolov1, Anna N. Zyrina2, Fedor F. Severin1,3
Apart from energy transformation, mitochondria play important signaling roles. In yeast, mitochondrial signaling relies on several molecular cascades. However, it is not clear how a cell detects a particular mitochondrial malfunction. In our review we argue that in yeast the major known routes of mitochondrial signaling are moderated by non-mitochondrial inputs.
Chlamydia trachomatis Genital Infections
Catherine M. O’Connell and Morgan E. Ferone
Chlamydia trachomatis infections are the most commonly reported sexually transmitted bacterial infections in the US and globally. Ascending infection may result in infertility, ectopic pregnancy and chronic pelvic pain in some women. In this review we provide an overview of current knowledge regarding epidemiology, disease outcomes and effective treatment of chlamydial genital tract infection and explore potential mechanisms facilitating C. trachomatis infection of genital mucosa identified via bioinformatics and other molecular approaches.
Physiology, phylogeny, and LUCA
William F. Martin1,2, Madeline C. Weiss1, Sinje Neukirchen3, Shijulal Nelson-Sathi4, Filipa L. Sousa3
Genomes record their own history. But if we want to look all the way back to life's beginnings some 4 billion years ago, the record of microbial evolution that is preserved in prokaryotic genomes is not easy to read. The classical approach has been to look for genes that are universally distributed. Another approach is to make all trees for all genes, and sift out the trees where signals have been overwritten by lateral gene transfer. What is left ought to be ancient. If we do that, what do we find?
Sexually transmitted infections: old foes on the rise
Didac Carmona-Gutierrez1,*, Katharina Kainz1 and Frank Madeo1,2,*
Sexually transmitted infections (STIs) are commonly spread via sexual contact. It is estimated that one million STIs are acquired every day worldwide. Besides their impact on sexual, reproductive and neonatal health, they can cause disastrous and life-threatening complications if left untreated. In addition to this personal burden, STIs also represent a socioeconomic problem, deriving in treatment costs of tremendous proportions. Despite a substantial progress in diagnosis, treatment and prevention, the incidence of many common STIs is increasing, and STIs continue to represent a global public health problem and a major cause for morbidity and mortality. With this Special Issue, Microbial Cell provides an in-depth overview of the eight major STIs, covering all relevant features of each infection.
Similar environments but diverse fates: Responses of budding yeast to nutrient deprivation.
Saul M. Honigberg
Diploid budding yeast (Saccharomyces cerevisiae) can adopt one of several alternative differentiation fates in response to nutrient limitation, and each of these fates provides distinct biological functions. When different strain backgrounds are taken into account, these various fates occur in response to similar environmental cues, are regulated by the same signal transduction pathways, and share many of the same master regulators. I propose that the relationships between fate choice, environmental cues and signaling pathways are not Boolean, but involve graded levels of signals, pathway activation and master-regulator activity.
Non-genetic impact factors on chronological lifespan and stress resistance of baker’s yeast
Michael Sauer and Diethard Mattanovich
This article comments on work published by Bisschops et al. (Microbial Cell, 2015), which illustrates how important the choice of the experimental setup is and how culture conditions influcence cellular aging and survival in biotechnological processes.
The complexities of bacterial-fungal interactions in the mammalian gastrointestinal tract
Eduardo Lopez-Medina1 and Andrew Y. Koh2
This article comments on work published by Lopez-Medina et al. (PLoS Pathog, 2015) and Fan et al. (Nat Med, 2015), which utilize an “artificial” niche, the antibiotic-treated gut with concomitant pathogenic microbe expansion, to gain insight in bacterial-fungal interactions in clinically common scenarios.
Gearing up for survival – HSP-containing granules accumulate in quiescent cells and promote survival
Ruofan Yu and Weiwei Dang
This article comments on work published by Lee et al. (Microbial Cell, 2016), which reports that distinct granules are formed in quiescent and non-quiescent cells, which determines their respective cell fates.
Construction and evaluation of yeast expression networks by database-guided predictions
May 10, 2016
DNA-Microarrays are powerful tools to obtain expression data on the genome-wide scale. We set out to define a way to cluster microarray data according to their expressional relationship and to obtain information on the significance of this clustering approach.
Optogenetic monitoring identifies phosphatidylthreonine-regulated calcium homeostasis in Toxoplasma gondii
May 1, 2016
Toxoplasma gondii is an obligate intracellular parasite, which inflicts acute as well as chronic infections in a wide range of warm-blooded vertebrates. Using an optogenetic sensor to monitor subcellular calcium in this model intracellular pathogen we found a novel regulatory function of phosphatidylthreonine in calcium signaling.
Filamentation protects Candida albicans from amphotericin B-induced programmed cell death via a mechanism involving the yeast metacaspase, MCA1
April 25, 2016
Candida albicans proliferates in two distinct cell types: blastopores and filaments. Programmed cell death is a controlled form of cell suicide that occurs when C. albicans cells are exposed to fungicidal drugs like amphotericin B and caspofungin, and to other stressful conditions. We provide evidence that programmed cell death is cell-type specific in yeast: Filamentous C. albicans cells are more resistant to amphotericin B- and caspofungin-induced programmed cell death than their blastospore counterparts. Our genetic data suggest that this phenomenon is mediated by a protective mechanism involving the yeast metacaspase, MCA1.
A plant Bcl-2-associated athanogene is proteolytically activated to confer fungal resistance
April 16, 2016
This article comments on work published by Li et al. (Plant Cell, 2016), which focuses on the role of Bcl-2-associated athanogene 6 (BAG6) in plant innate immunity, showing that BAG6 plays a key role in basal plant defense against fungal pathogens.
The molecular and cellular action properties of artemisinins: what has yeast told us?
April 14, 2016
Artemisinin (ART) or Qinghaosu is a natural compound possessing superior anti-malarial activity. Although intensive studies have been done in the medicinal chemistry field to understand the structure-effect relationship, the biological actions of artemisinin are poorly understood and controversial. This review summarizes what we have learned from yeast about the basic biological properties of ARTs, as well as some key unanswered questions.
Formaldehyde fixation is detrimental to actin cables in glucose-depleted S. cerevisiae cells
April 13, 2016
Actin filaments form cortical patches and emanating cables in fermenting cells of Saccharomyces cerevisiae. We assume that stability of actin cables reflects the metabolic status of the cell. Based on comparison of live and formaldehyde-fixed cells, our data suggest that formaldehyde affects respiration before fixation and this uneven signaling results in destabilization of actin cables in glucose-deprived cells.
Non-genetic impact factors on chronological lifespan and stress resistance of baker’s yeast
April 13, 2016
This article comments on work published by Bisschops et al. (Microbial Cell, 2015), which illustrates how important the choice of the experimental setup is and how culture conditions influcence cellular aging and survival in biotechnological processes.
Chemical proteomics approach reveals the direct targets and the heme-dependent activation mechanism of artemisinin in Plasmodium falciparum using an activity-based artemisinin probe
April 5, 2016
This article comments on work published by Wang et al. (Nat Commun, 2014), which provides insights into the mode-of-action of artemisinin and its specificity against malaria parasites.
Translational repression in malaria sporozoites
April 5, 2016
This article comments on work published by Zhang et al. (PLoS Pathog, 2016), which summarizea recent advances in the translational repression of gene expression in the malaria sporozoite.
Autophagy: one more Nobel Prize for yeast
Andreas Zimmermann1, Katharina Kainz1, Aleksandra Andryushkova1, Sebastian Hofer1, Frank Madeo1,2 and Didac Carmona-Gutierrez1
The recent announcement of the 2016 Nobel Prize in Physiology or Medicine, awarded to Yoshinori Ohsumifor the discoveries of mechanisms governing autophagy, underscores the importance of intracellular degradation and recycling. Here we provide a quick historical overview that mirrors both the importance of autophagy as a conserved and essential process for cellular life and death as well as the crucial role of yeast in its mechanistic characterization.