scholarly journals Nuclear Localization of Haa1, Which Is Linked to Its Phosphorylation Status, Mediates Lactic Acid Tolerance in Saccharomyces cerevisiae

2014 ◽  
Vol 80 (11) ◽  
pp. 3488-3495 ◽  
Author(s):  
Minetaka Sugiyama ◽  
Shin-Pei Akase ◽  
Ryota Nakanishi ◽  
Hitoshi Horie ◽  
Yoshinobu Kaneko ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactic Acid ◽  
Subcellular Localization ◽  
Target Genes ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Acid Resistance ◽  
Nuclear Accumulation ◽  
Content Type ◽  
Adaptation Response

ABSTRACTImprovement of the lactic acid resistance of the yeastSaccharomyces cerevisiaeis important for the application of the yeast in industrial production of lactic acid from renewable resources. However, we still do not know the precise mechanisms of the lactic acid adaptation response in yeast and, consequently, lack effective approaches for improving its lactic acid tolerance. To enhance our understanding of the adaptation response, we screened forS. cerevisiaegenes that confer enhanced lactic acid resistance when present in multiple copies and identified the transcriptional factor Haa1 as conferring resistance to toxic levels of lactic acid when overexpressed. The enhanced tolerance probably results from increased expression of its target genes. When cells that expressed Haa1 only from the endogenous promoter were exposed to lactic acid stress, the main subcellular localization of Haa1 changed from the cytoplasm to the nucleus within 5 min. This nuclear accumulation induced upregulation of the Haa1 target genesYGP1,GPG1, andSPI1, while the degree of Haa1 phosphorylation observed under lactic acid-free conditions decreased. Disruption of the exportin geneMSN5led to accumulation of Haa1 in the nucleus even when no lactic acid was present. Since Msn5 was reported to interact with Haa1 and preferentially exports phosphorylated cargo proteins, our results suggest that regulation of the subcellular localization of Haa1, together with alteration of its phosphorylation status, mediates the adaptation to lactic acid stress in yeast.

scholarly journals Improved Acetic Acid Resistance in Saccharomyces cerevisiae by Overexpression of theWHI2Gene Identified through Inverse Metabolic Engineering

2016 ◽  
Vol 82 (7) ◽  
pp. 2156-2166 ◽  
Author(s):  
Yingying Chen ◽  
Lisa Stabryla ◽  
Na Wei
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Metabolic Engineering ◽  
Acid Stress ◽  
Acid Resistance ◽  
Biofuel Production ◽  
Gene Target ◽  
Content Type ◽  
Inverse Metabolic Engineering ◽  
Acetic Acid Resistance

ABSTRACTDevelopment of acetic acid-resistantSaccharomyces cerevisiaeis important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target,WHI2(encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance inS. cerevisiae. Overexpression ofWHI2significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. TheWHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression ofWHI2gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 inS. cerevisiae. Meanwhile, thewhi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response inS. cerevisiae. Additionally, overexpression ofWHI2and of a cognate phosphatase gene,PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production.

scholarly journals D-Methionine and D-Phenylalanine Improve Lactococcus lactis F44 Acid Resistance and Nisin Yield by Governing Cell Wall Remodeling

2020 ◽  
Vol 86 (9) ◽  
Author(s):  
Hao Wu ◽  
Ershu Xue ◽  
Ning Zhi ◽  
Qianqian Song ◽  
Kairen Tian ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Lactococcus Lactis ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Acid Resistance ◽  
Cell Wall Synthesis ◽  
Nisin Production ◽  
Content Type ◽  
Nisin Yield

ABSTRACT Lactococcus lactis encounters various environmental challenges, especially acid stress, during its growth. The cell wall can maintain the integrity and shape of the cell under environmental stress, and d-amino acids play an important role in cell wall synthesis. Here, by analyzing the effects of 19 different d-amino acids on the physiology of L. lactis F44, we found that exogenously supplied d-methionine and d-phenylalanine increased the nisin yield by 93.22% and 101.29%, respectively, as well as significantly increasing the acid resistance of L. lactis F44. The composition of the cell wall in L. lactis F44 with exogenously supplied d-Met or d-Phe was further investigated via a vancomycin fluorescence experiment and a liquid chromatography-mass spectrometry assay, which demonstrated that d-Met could be incorporated into the fifth position of peptidoglycan (PG) muropeptides and d-Phe could be added to the fourth and fifth positions. Moreover, overexpression of the PG synthesis gene murF further enhanced the levels of d-Met and d-Phe involved in PG and increased the survival rate under acid stress and the nisin yield of the strain. This study reveals that the exogenous supply of d-Met or d-Phe can change the composition of the cell wall and influence acid tolerance as well as nisin yield in L. lactis. IMPORTANCE As d-amino acids play an important role in cell wall synthesis, we analyzed the effects of 19 different d-amino acids on L. lactis F44, demonstrating that d-Met and d-Phe can participate in peptidoglycan (PG) synthesis and improve the acid resistance and nisin yield of this strain. murF overexpression further increased the levels of d-Met and d-Phe incorporated into PG and contributed to the acid resistance of the strain. These findings suggest that d-Met and d-Phe can be incorporated into PG to improve the acid resistance and nisin yield of L. lactis, and this study provides new ideas for the enhancement of nisin production.

scholarly journals Transcriptional Response to Lactic Acid Stress in the Hybrid Yeast Zygosaccharomyces parabailii

2017 ◽  
Vol 84 (5) ◽  
Author(s):  
Raúl A. Ortiz-Merino ◽  
Nurzhan Kuanyshev ◽  
Kevin P. Byrne ◽  
Javier A. Varela ◽  
John P. Morrissey ◽  
...  
Keyword(s):  
Gene Expression ◽  
Lactic Acid ◽  
Lactic Acid Production ◽  
Acid Stress ◽  
Transcriptional Response ◽  
Acid Tolerance ◽  
Rna Seq ◽  
Content Type ◽  
Mrna Sequencing ◽  
Interspecies Hybrid

ABSTRACT Lactic acid has a wide range of applications starting from its undissociated form, and its production using cell factories requires stress-tolerant microbial hosts. The interspecies hybrid yeast Zygosaccharomyces parabailii has great potential to be exploited as a novel host for lactic acid production, due to high organic acid tolerance at low pH and a fermentative metabolism with a high growth rate. Here we used mRNA sequencing (RNA-seq) to analyze Z. parabailii 's transcriptional response to lactic acid added exogenously, and we explore the biological mechanisms involved in tolerance. Z. parabailii contains two homeologous copies of most genes. Under lactic acid stress, the two genes in each homeolog pair tend to diverge in expression to a significantly greater extent than under control conditions, indicating that stress tolerance is facilitated by interactions between the two gene sets in the hybrid. Lactic acid induces downregulation of genes related to cell wall and plasma membrane functions, possibly altering the rate of diffusion of lactic acid into cells. Genes related to iron transport and redox processes were upregulated, suggesting an important role for respiratory functions and oxidative stress defense. We found differences in the expression profiles of genes putatively regulated by Haa1 and Aft1/Aft2, previously described as lactic acid responsive in Saccharomyces cerevisiae . Furthermore, formate dehydrogenase ( FDH ) genes form a lactic acid-responsive gene family that has been specifically amplified in Z. parabailii in comparison to other closely related species. Our study provides a useful starting point for the engineering of Z. parabailii as a host for lactic acid production. IMPORTANCE Hybrid yeasts are important in biotechnology because of their tolerance to harsh industrial conditions. The molecular mechanisms of tolerance can be studied by analyzing differential gene expression under conditions of interest and relating gene expression patterns to protein functions. However, hybrid organisms present a challenge to the standard use of mRNA sequencing (RNA-seq) to study transcriptional responses to stress, because their genomes contain two similar copies of almost every gene. Here we used stringent mapping methods and a high-quality genome sequence to study the transcriptional response to lactic acid stress in Zygosaccharomyces parabailii ATCC 60483, a natural interspecies hybrid yeast that contains two complete subgenomes that are approximately 7% divergent in sequence. Beyond the insights we gained into lactic acid tolerance in this study, the methods we developed will be broadly applicable to other yeast hybrid strains.

scholarly journals Enhancement of Acetic Acid Tolerance in Saccharomyces cerevisiae by Overexpression of theHAA1Gene, Encoding a Transcriptional Activator

2012 ◽  
Vol 78 (22) ◽  
pp. 8161-8163 ◽  
Author(s):  
Koichi Tanaka ◽  
Yukari Ishii ◽  
Jun Ogawa ◽  
Jun Shima
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Transcriptional Activator ◽  
Wild Type ◽  
Acetic Acid Tolerance ◽  
Content Type ◽  
In The Wild ◽  
Overexpressing Strain

ABSTRACTHaa1 is a transcriptional activator required forSaccharomyces cerevisiaeadaptation to weak acids. Here we show that the constitutiveHAA1-overexpressing strain acquired a higher level of acetic acid tolerance. Under conditions of acetic acid stress, the intracellular level of acetic acid was significantly lower inHAA1-overexpressing cells than in the wild-type cells.

scholarly journals Human Pathogenic Candida Species Respond Distinctively to Lactic Acid Stress

2020 ◽  
Vol 6 (4) ◽  
pp. 348
Author(s):  
Isabella Zangl ◽  
Reinhard Beyer ◽  
Ildiko-Julia Pap ◽  
Joseph Strauss ◽  
Christoph Aspöck ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Carbon Source ◽  
Candida Species ◽  
Fungal Pathogens ◽  
Phenotypic Variability ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Candida Spp ◽  
Vaginal Tract ◽  
High Concentrations

Several Candida species are opportunistic human fungal pathogens and thrive in various environmental niches in and on the human body. In this study we focus on the conditions of the vaginal tract, which is acidic, hypoxic, glucose-deprived, and contains lactic acid. We quantitatively analyze the lactic acid tolerance in glucose-rich and glucose-deprived environment of five Candida species: Candidaalbicans, Candida glabrata, Candida parapsilosis, Candida krusei and Candida tropicalis. To characterize the phenotypic space, we analyzed 40–100 clinical isolates of each species. Each Candida species had a very distinct response pattern to lactic acid stress and characteristic phenotypic variability. C. glabrata and C. parapsilosis were best to withstand high concentrations of lactic acid with glucose as carbon source. A glucose-deprived environment induced lactic acid stress tolerance in all species. With lactate as carbon source the growth rate of C. krusei is even higher compared to glucose, whereas the other species grow slower. C. krusei may use lactic acid as carbon source in the vaginal tract. Stress resistance variability was highest among C. parapsilosis strains. In conclusion, each Candida spp. is adapted differently to cope with lactic acid stress and resistant to physiological concentrations.

scholarly journals Molecular Design of a Signaling System Influences Noise in Protein Abundance under Acid Stress in Different Gammaproteobacteria

2020 ◽  
Vol 202 (16) ◽  
Author(s):  
Sophie Brameyer ◽  
Elisabeth Hoyer ◽  
Sebastian Bibinger ◽  
Korinna Burdack ◽  
Jürgen Lassak ◽  
...  
Keyword(s):  
Copy Number ◽  
Molecular Design ◽  
Ph Sensor ◽  
Acid Stress ◽  
Acid Resistance ◽  
Signaling System ◽  
Content Type ◽  
Signaling Systems ◽  
E Coli ◽  
Cad System

ABSTRACT Bacteria have evolved different signaling systems to sense and adapt to acid stress. One of these systems, the CadABC system, responds to a combination of low pH and lysine availability. In Escherichia coli, the two signals are sensed by the pH sensor and transcription activator CadC and the cosensor LysP, a lysine-specific transporter. Activated CadC promotes the transcription of the cadBA operon, which codes for the lysine decarboxylase CadA and the lysine/cadaverine antiporter CadB. The copy number of CadC is controlled translationally. Using a bioinformatics approach, we identified the presence of CadC with ribosomal stalling motifs together with LysP in species of the Enterobacteriaceae family. In contrast, we identified CadC without stalling motifs in species of the Vibrionaceae family, and the LysP cosensor is missing. Therefore, we compared the outputs of the Cad system in single cells of the distantly related organisms E. coli and Vibrio campbellii using fluorescently tagged CadB as the reporter. We observed a heterogeneous output in E. coli, and all the V. campbellii cells produced CadB. The copy number of the pH sensor CadC in E. coli was extremely low (≤4 molecules per cell), but it was 10-fold higher in V. campbellii. An increase in the CadC copy number in E. coli correlated with a decrease in heterogeneous behavior. This study demonstrated how small changes in the design of a signaling system allow a homogeneous output and, thus, adaptation of Vibrio species that rely on the CadABC system as the only acid resistance system. IMPORTANCE Acid resistance is an important property for bacteria, such as Escherichia coli, to survive acidic environments like the human gastrointestinal tract. E. coli possesses both passive and inducible acid resistance systems to counteract acidic environments. Thus, E. coli evolved sophisticated signaling systems to sense and appropriately respond to environmental acidic stress by regulating the activity of its three inducible acid resistance systems. One of these systems is the Cad system, which is induced only under moderate acidic stress in a lysine-rich environment by the pH-responsive transcriptional regulator CadC. The significance of our research lies in identifying the molecular design of the Cad systems in different proteobacteria and their target expression noise at the single-cell level during acid stress conditions.

scholarly journals GlnR Negatively Regulates Glutamate-Dependent Acid Resistance in Lactobacillus brevis

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Luchan Gong ◽  
Cong Ren ◽  
Yan Xu
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Glutamate Decarboxylase ◽  
Wild Type Strain ◽  
Acid Resistance ◽  
Lactobacillus Brevis ◽  
Deletion Strain ◽  
Content Type ◽  
Gaba Production ◽  
Encoding Gene

ABSTRACT Lactic acid bacteria often encounter a variety of multiple stresses in their natural and industrial fermentation environments. The glutamate decarboxylase (GAD) system is one of the most important acid resistance systems in lactic acid bacteria. In this study, we demonstrated that GlnR, a nitrogen regulator in Gram-positive bacteria, directly modulated γ-aminobutyric acid (GABA) conversion from glutamate and was involved in glutamate-dependent acid resistance in Lactobacillus brevis. The glnR deletion strain (ΔglnR mutant) achieved a titer of 284.7 g/liter GABA, which is 9.8-fold higher than that of the wild-type strain. The cell survival of the glnR deletion strain was significantly higher than that of the wild-type strain under the condition of acid challenge and was positively correlated with initial glutamate concentration and GABA production. Quantitative reverse transcription-PCR assays demonstrated that GlnR inhibited the transcription of the glutamate decarboxylase-encoding gene (gadB), glutamate/GABA antiporter-encoding gene (gadC), glutamine synthetase-encoding gene (glnA), and specific transcriptional regulator-encoding gene (gadR) involved in gadCB operon regulation. Moreover, GABA production and glutamate-dependent acid resistance were absolutely abolished in the gadR glnR deletion strain. Electrophoretic mobility shift and DNase I footprinting assays revealed that GlnR directly bound to the 5′-untranslated regions of the gadR gene and gadCB operon, thus inhibiting their transcription. These results revealed a novel regulatory mechanism of GlnR on glutamate-dependent acid resistance in Lactobacillus. IMPORTANCE Free-living lactic acid bacteria often encounter acid stresses because of their organic acid-producing features. Several acid resistance mechanisms, such as the glutamate decarboxylase system, F1Fo-ATPase proton pump, and alkali production, are usually employed to relieve growth inhibition caused by acids. The glutamate decarboxylase system is vital for GAD-containing lactic acid bacteria to protect cells from DNA damage, enzyme inactivation, and product yield loss in acidic habitats. In this study, we found that a MerR-type regulator, GlnR, was involved in glutamate-dependent acid resistance by directly regulating the transcription of the gadR gene and gadCB operon, resulting in an inhibition of GABA conversion from glutamate in L. brevis. This study represents a novel mechanism for GlnR's regulation of glutamate-dependent acid resistance and also provides a simple and novel strategy to engineer Lactobacillus strains to elevate their acid resistance as well as GABA conversion from glutamate.

Comparative Analysis of Acid Resistance between Susceptible and Multi-Antimicrobial-Resistant Salmonella Strains Cultured under Stationary-Phase Acid Tolerance–Inducing and Noninducing Conditions

2003 ◽  
Vol 66 (5) ◽  
pp. 732-740 ◽  
Author(s):  
R. T. BACON ◽  
J. N. SOFOS ◽  
P. A. KENDALL ◽  
K. E. BELK ◽  
G. C. SMITH
Keyword(s):  
Stationary Phase ◽  
Antimicrobial Agents ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Acid Resistance ◽  
Low Ph ◽  
Acid Exposure ◽  
Acid Adaptation ◽  
Acid Shock ◽  
Resistant Strains

This study compared acid resistance levels among five antimicrobial-susceptible strains of Salmonella and five strains that were simultaneously resistant to a minimum of six antimicrobial agents. The induction of a stationary-phase acid tolerance response (ATR) was attempted by both transient low-pH acid shock and acid adaptation. For acid shock induction, strains were grown for 18 h in minimal E medium containing 0.4% glucose (EG medium) and exposed to sublethal acid stress (pH 4.3) for 2 h, and subsequently, both shocked and nonshocked cultures were acid challenged (pH 3.0) for 4 h. Acid adaptation was achieved by growing strains for 18 h in tryptic soy broth containing 1.0% glucose (TSB+G), while nonadapted cultures were grown for 18 h in glucose-free tryptic soy broth (TSB−G). Acid-adapted and nonadapted inocula were acid challenged (pH 2.3) for 4 h. Initial (0 h) mean populations of nonchallenged Salmonella were 8.5 to 8.7, 8.4 to 8.8, and 8.2 to 8.3 log CFU/ml for strains grown in EG medium, TSB−G, and TSB+G, respectively. After 4 h of acid challenge, mean populations were 3.0 to 4.8 and 2.5 to 3.7 log CFU/ml for previously acid-shocked susceptible and resistant strains, respectively, while corresponding counts for nonshocked strains were 4.3 to 5.5 log CFU/ml and 3.9 to 4.9 log CFU/ml. Following 4 h of acid exposure, acid-adapted cultures of susceptible and resistant strains had mean populations of 6.1 to 6.4 log CFU/ml and 6.4 to 6.6 log CFU/ml, respectively, while corresponding counts for nonadapted cultures were 1.9 to 2.1 log CFU/ml and 1.8 to 2.0 log CFU/ml, respectively. A low-pH–inducible ATR was not achieved through transient acid shock, while an ATR was evident following acid adaptation, as adapted populations were 4.2 to 4.8 log units larger than nonadapted populations following acid exposure. Although some strain-dependent variations in acid resistance were observed, results from this study suggest no association between susceptibility to antimicrobial agents and the ability of the Salmonella strains evaluated to survive low-pH stress.

Sign in / Sign up

Export Citation Format

Share Document