Research, Research Articles
RidA proteins contribute to fitness of S. enterica and E. coli by reducing 2AA stress and moderating flux to isoleucine biosynthesis
Ronnie L. Fulton, Bryce R. Sawyer and Diana M Downs
This study solidifies the established role of RidA in removing 2AA, while also presenting evidence for a role of RidA in enhancing flux towards isoleucine biosynthesis in E. coli. Overall, these data emphasize that metabolic networks can generate distinct responses to perturbation, even when the individual components are conserved.
Fecal gelatinase does not predict mortality in patients with alcohol-associated hepatitis
Yongqiang Yang1,a, Philipp Hartmann2,3,a and Bernd Schnabl1,4
This study aimed to investigate the significance of fecal gelatinase on clinical outcomes in patients with alcohol-associated hepatitis. In conclusion, in our cohort, fecal gelatinase does not predict mortality and does not indicate higher disease severity in patients with alcohol-associated hepatitis.
Direct detection of stringent alarmones (pp)pGpp using malachite green
Muriel Schicketanz1, Magdalena Petrová2, Dominik Rejman2, Margherita Sosio3, Stefano Donadio3 and Yong Everett Zhang1
In this study, we demonstrate the surprising discovery of a commercially available, low-cost malachite green (MG) detection kit, originally designed for orthophosphate (Pi) detection, for detecting (p)ppGpp and its analogues, especially pGpp
Promoter methylation and increased expression of PD-L1 in patients with active tuberculosis
Yen-Han Tseng1,2, Sheng-Wei Pan1,2,3, Jhong-Ru Huang2,4, Chang-Ching Lee1, Jung-Jyh Hung2,5, Po-Kuei Hsu2,5, Nien-Jung Chen6, Wei-Juin Su2,7, Yuh-Min Chen1,2 and Jia-Yih Feng1,2,8
The PD-1/PD-L1 pathway plays a pivotal role in T cell activity and is involved in the pathophysiology of tuberculosis. Here we show that PD-L1 expression is increased in patients with active tuberculosis and is correlated with treatment outcomes.
Quantification methods of Candida albicans are independent irrespective of fungal morphology
Amanda B Soares1, Maria C de Albuquerque1, Leticia M Rosa1, Marlise I Klein 2, Ana C Paravina1, Paula A Barbugli1, Livia N Dovigo3 and Ewerton G de O Mima1
Our study demonstrated that the quantification methods of C. albicans (cells/mL, CFU/mL, and vPCR) did not agree, regardless of the fungal morphology/growth, even though a significant and strong correlation is observed.
Pathogenic Escherichia coli change the adhesion between neutrophils and endotheliocytes in the experimental bacteremia model
Svetlana N Pleskova1,2,*, Nikolay A Bezrukov1, Sergey Z Bobyk1, Ekaterina N Gorshkova1 and Dimitri V Novikov3
In this work, we have demonstrated that in the model of experimental septicemia there is a disruption of adhesion contacts between neutrophils and endothelial cells, manifested by a decrease in adhesion force and work upon exposure to E. coli.
Arsenite treatment induces Hsp90 aggregates distinct from conventional stress granules in fission yeast
Naofumi Tomimotoa, Teruaki Takasakia and Reiko Sugiura
Given the conserved role of Hsp90 as a molecular chaperone protein, our findings presented in this study may suggest a novel type of arsenite-induced biological condensates, wherein Hsp90 plays a key role in maintaining its integrity.
Unresolved mystery of cyclic nucleotide second messengers, periplasmic acid phosphatases and bacterial natural competence
Kristina Kronborg and Yong Everett Zhang
In this study we aimed to identify the promotors responsible for the expression of the non-specific acid phosphatase AphA during different starvation conditions, to confirm the requirement of the cAMP-dependent CRP regulon for aphA expression, and to finally identify regulators of its expression.
Expansion of metabolically labelled endocytic organelles and cytoskeletal cell structures in Giardia lamblia using optimised U- ExM protocols
Clirim Jetishi1,2,a, Erina A. Balmer1,2,a, Bianca M. Berger1,2,a, Carmen Faso1,3,4 and Torsten Ochsenreiter1
Understanding cellular ultrastructure is tightly bound to microscopic resolution and the ability to identify individual components at that resolution. In this study we demonstrate mostly isotropic 4.5-fold expansion of several different compartments in Giardia cells and present an optimised, shortened, and modular protocol that can be swiftly adjusted to the investigators needs.
Impact of histone H4K16 acetylation on the meiotic recombination checkpoint in Saccharomyces cerevisiae
December 4, 2016
In meiotic cells, the pachytene checkpoint or meiotic recombination checkpoint is a surveillance mechanism that monitors critical processes, such as recombination and chromosome synapsis, which are essential for proper distribution of chromosomes to the meiotic progeny. We report here that Sas2-mediated acetylation of histone H4 at lysine 16 (H4K16ac) modulates meiotic checkpoint activity in response to synaptonemal complex defects. Our results reveal that proper levels of H4K16ac orchestrate this meiotic quality control mechanism and that Sir2 impinges on additional targets to fully activate the checkpoint.
The ubiquitin-conjugating enzyme, Ubc1, indirectly regulates SNF1 kinase activity via Forkhead-dependent transcription
November 5, 2016
The SNF1 kinase class of serine/threonine kinases, which includes the AMP-dependent protein kinase (AMPK) in other systems, are of widespread interest because of their important roles in glucose homeostasis, stress resistance, and aging. Our goal was to identify discrete ubiquitin-conjugating enzymes that are involved in SNF1 kinase activity in response to glucose levels and anticipated revealing those which are involved in Snf1-Ub attachment. Here, we report that the cell cycle and stress-related E2, Ubc1, indirectly affects SNF1 kinase activity not through stability, but through upstream events.
Phylogenetic profiles of all membrane transport proteins of the malaria parasite highlight new drug targets
August 30, 2016
In order to combat the on-going malaria epidemic, discovery of new drug targets remains vital. Proteins that are essential to survival and specific to malaria parasites are key candidates. Here, we present a comprehensive orthology assignment of all Plasmodium falciparum putative membrane transport proteins and provide a detailed overview of the associated essential gene functions obtained through experimental genetics studies in human and murine model parasites.
VDAC regulates AAC-mediated apoptosis and cytochrome c release in yeast
August 25, 2016
Mitochondrial outer membrane permeabilization is a key event in apoptosis processes leading to the release of lethal factors. In this study, we sought to determine whether Por1p functionally interacts with ADP/ATP carrier (AAC) proteins, as well as its contribution to cytochrome c release and yeast apoptosis induced by acetic acid treatment. Our data indicate that Por1p may regulate cell survival by acting as a negative regulator of AAC proteins in the apoptotic cascade.
Attenuation of polyglutamine-induced toxicity by enhancement of mitochondrial OXPHOS in yeast and fly models of aging
July 26, 2016
Defects in mitochondrial biogenesis and function are common in many neurodegenerative disorders, including Huntington’s disease (HD). We could shown that enhancement of mitochondrial biogenesis protects against neurodegeneration in HD yeast and fly models. Our results suggest that therapeutic interventions aiming at the enhancement of mitochondrial respiration and OXPHOS could reduce polyQ toxicity and delay disease onset.
Cox1 mutation abrogates need for Cox23 in cytochrome c oxidase biogenesis
June 30, 2016
Cox23 is a known conserved assembly factor for cytochrome c oxidase, although its role in cytochrome c oxidase (CcO) biogenesis remains unresolved. To gain additional insights into its role, we isolated spontaneous suppressors of the respiratory growth defect in cox23∆ yeast cells. In this report, we describe the isolation of a robust suppressor of the respiratory defect in cox23∆ cells that mapped to the mitochondrial-encoded Cox1 subunit.
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.
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.
Insights into dynamin-associated disorders through analysis of equivalent mutations in the yeast dynamin Vps1
March 22, 2016
The dynamins represent a superfamily of proteins that have been shown to function in a wide range of membrane fusion and fission events. An increasing number of mutations in the human classical dynamins, Dyn-1 and Dyn-2 has been reported, with diseases caused by these changes ranging from Charcot-Marie-Tooth disorder to epileptic encephalopathies. This study aimed to use the dynamin-like protein Vps1 of Saccharomyces cerevisiae as a model to gain insights into the mechanistic defects caused by specific dynamin mutations considered to underlie a number of diseases.