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Sofer S, Vershinin Z, Mashni L, Zalk R, Shahar A, Eichler J, Grossman-Haham I. Perturbed N-glycosylation of Halobacterium salinarum archaellum filaments leads to filament bundling and compromised cell motility. Nat Commun 2024; 15:5841. [PMID: 38992036 PMCID: PMC11239922 DOI: 10.1038/s41467-024-50277-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 07/03/2024] [Indexed: 07/13/2024] Open
Abstract
The swimming device of archaea-the archaellum-presents asparagine (N)-linked glycans. While N-glycosylation serves numerous roles in archaea, including enabling their survival in extreme environments, how this post-translational modification contributes to cell motility remains under-explored. Here, we report the cryo-EM structure of archaellum filaments from the haloarchaeon Halobacterium salinarum, where archaellins, the building blocks of the archaellum, are N-glycosylated, and the N-glycosylation pathway is well-resolved. We further determined structures of archaellum filaments from two N-glycosylation mutant strains that generate truncated glycans and analyzed their motility. While cells from the parent strain exhibited unidirectional motility, the N-glycosylation mutant strain cells swam in ever-changing directions within a limited area. Although these mutant strain cells presented archaellum filaments that were highly similar in architecture to those of the parent strain, N-linked glycan truncation greatly affected interactions between archaellum filaments, leading to dramatic clustering of both isolated and cell-attached filaments. We propose that the N-linked tetrasaccharides decorating archaellins act as physical spacers that minimize the archaellum filament aggregation that limits cell motility.
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Affiliation(s)
- Shahar Sofer
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Zlata Vershinin
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Leen Mashni
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Ran Zalk
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Anat Shahar
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Iris Grossman-Haham
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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2
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Hackley RK, Hwang S, Herb JT, Bhanap P, Lam K, Vreugdenhil A, Darnell CL, Pastor MM, Martin JH, Maupin-Furlow JA, Schmid AK. TbsP and TrmB jointly regulate gapII to influence cell development phenotypes in the archaeon Haloferax volcanii. Mol Microbiol 2024; 121:742-766. [PMID: 38204420 PMCID: PMC11023807 DOI: 10.1111/mmi.15225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 12/09/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024]
Abstract
Microbial cells must continually adapt their physiology in the face of changing environmental conditions. Archaea living in extreme conditions, such as saturated salinity, represent important examples of such resilience. The model salt-loving organism Haloferax volcanii exhibits remarkable plasticity in its morphology, biofilm formation, and motility in response to variations in nutrients and cell density. However, the mechanisms regulating these lifestyle transitions remain unclear. In prior research, we showed that the transcriptional regulator, TrmB, maintains the rod shape in the related species Halobacterium salinarum by activating the expression of enzyme-coding genes in the gluconeogenesis metabolic pathway. In Hbt. salinarum, TrmB-dependent production of glucose moieties is required for cell surface glycoprotein biogenesis. Here, we use a combination of genetics and quantitative phenotyping assays to demonstrate that TrmB is essential for growth under gluconeogenic conditions in Hfx. volcanii. The ∆trmB strain rapidly accumulated suppressor mutations in a gene encoding a novel transcriptional regulator, which we name trmB suppressor, or TbsP (a.k.a. "tablespoon"). TbsP is required for adhesion to abiotic surfaces (i.e., biofilm formation) and maintains wild-type cell morphology and motility. We use functional genomics and promoter fusion assays to characterize the regulons controlled by each of TrmB and TbsP, including joint regulation of the glucose-dependent transcription of gapII, which encodes an important gluconeogenic enzyme. We conclude that TrmB and TbsP coregulate gluconeogenesis, with downstream impacts on lifestyle transitions in response to nutrients in Hfx. volcanii.
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Affiliation(s)
- Rylee K. Hackley
- Biology Department, Duke University, Durham, North Carolina, USA
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, USA
| | - Sungmin Hwang
- Biology Department, Duke University, Durham, North Carolina, USA
| | - Jake T. Herb
- Biology Department, Duke University, Durham, North Carolina, USA
| | - Preeti Bhanap
- Biology Department, Duke University, Durham, North Carolina, USA
| | - Katie Lam
- Biology Department, Duke University, Durham, North Carolina, USA
| | | | | | | | - Johnathan H. Martin
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA
| | - Julie A. Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA
- Genetics Institute, University of Florida, Gainesville, Florida, USA
| | - Amy K. Schmid
- Biology Department, Duke University, Durham, North Carolina, USA
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, USA
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3
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Vershinin Z, Zaretsky M, Guan Z, Eichler J. Agl28 and Agl29 are key components of a Halobacterium salinarum N-glycosylation pathway. FEMS Microbiol Lett 2023; 370:fnad017. [PMID: 36866517 PMCID: PMC10022576 DOI: 10.1093/femsle/fnad017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/20/2023] [Accepted: 02/28/2023] [Indexed: 03/04/2023] Open
Abstract
Although Halobacterim salinarum provided the first example of N-glycosylation outside the Eukarya, only recently has attention focused on delineating the pathway responsible for the assembly of the N-linked tetrasaccharide decorating selected proteins in this haloarchaeon. In the present report, the roles of VNG1053G and VNG1054G, two proteins encoded by genes clustered together with a set of genes demonstrated to encode N-glycosylation pathway components, were considered. Relying on both bioinformatics and gene deletion and subsequent mass spectrometry analysis of known N-glycosylated proteins, VNG1053G was determined to be the glycosyltransferase responsible for addition of the linking glucose, while VNG1054G was deemed to be the flippase that translocates the lipid-bound tetrasaccharide across the plasma membrane to face the cell exterior, or to contribute to such activity. As observed with Hbt. salinarum lacking other components of the N-glycosylation machinery, both cell growth and motility were compromised in the absence of VNG1053G or VNG1054G. Thus, given their demonstrated roles in Hbt. salinarum N-glycosylation, VNG1053G and VNG1054G were re-annotated as Agl28 and Agl29, according to the nomenclature used to define archaeal N-glycosylation pathway components.
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Affiliation(s)
- Zlata Vershinin
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Beersheva 84105, Israel
| | - Marianna Zaretsky
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Beersheva 84105, Israel
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, United States
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Beersheva 84105, Israel
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4
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Notaro A, Vershinin Z, Guan Z, Eichler J, De Castro C. An N-linked tetrasaccharide from Halobacterium salinarum presents a novel modification, sulfation of iduronic acid at the O-3 position. Carbohydr Res 2022; 521:108651. [PMID: 36037649 DOI: 10.1016/j.carres.2022.108651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/15/2022] [Accepted: 08/15/2022] [Indexed: 11/16/2022]
Abstract
Halobacterium salinarum, a halophilic archaeon that grows at near-saturating salt concentrations, provided the first example of N-glycosylation outside Eukarya. Yet, almost 50 years later, numerous aspects of such post-translational protein processing in this microorganism remain to be determined, including the architecture of glycoprotein-bound glycans. In the present report, nuclear magnetic resonance spectroscopy was used to define a tetrasaccharide N-linked to both archaellins, building blocks of the archaeal swimming device (the archaellum), and the S-layer glycoprotein that comprises the protein shell surrounding the Hbt. salinarum cell as β-GlcA(2S)-(1 → 4)-α-IdoA(3S)-(1 → 4)-β-GlcA-(1 → 4)-β-Glc-Asn. The structure of this tetrasaccharide fills gaps remaining from previous studies, including confirmation of the first known inclusion of iduronic acid in an archaeal N-linked glycan. At the same time, the sulfation of this iduronic acid at the O-3 position has not, to the best of our knowledge, been previously seen. As such, this may represent yet another unique facet of N-glycosylation in Archaea.
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Affiliation(s)
- Anna Notaro
- Department of Agricultural Sciences, University of Napoli Federico II, Portici, Italy
| | - Zlata Vershinin
- Department of Life Sciences, Ben-Gurion University of the Negev, Beersheva, Israel
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Beersheva, Israel.
| | - Cristina De Castro
- Department of Agricultural Sciences, University of Napoli Federico II, Portici, Italy.
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Abstract
Oxidative stress causes cellular damage, including DNA mutations, protein dysfunction, and loss of membrane integrity. Here, we discovered that a TrmB (transcription regulator of mal operon) family protein (Pfam PF01978) composed of a single winged-helix DNA binding domain (InterPro IPR002831) can function as thiol-based transcriptional regulator of oxidative stress response. Using the archaeon Haloferax volcanii as a model system, we demonstrate that the TrmB-like OxsR is important for recovery of cells from hypochlorite stress. OxsR is shown to bind specific regions of genomic DNA, particularly during hypochlorite stress. OxsR-bound intergenic regions were found proximal to oxidative stress operons, including genes associated with thiol relay and low molecular weight thiol biosynthesis. Further analysis of a subset of these sites revealed OxsR to function during hypochlorite stress as a transcriptional activator and repressor. OxsR was shown to require a conserved cysteine (C24) for function and to use a CG-rich motif upstream of conserved BRE/TATA box promoter elements for transcriptional activation. Protein modeling suggested the C24 is located at a homodimer interface formed by antiparallel α helices, and that oxidation of this cysteine would result in the formation of an intersubunit disulfide bond. This covalent linkage may promote stabilization of an OxsR homodimer with the enhanced DNA binding properties observed in the presence of hypochlorite stress. The phylogenetic distribution TrmB family proteins, like OxsR, that have a single winged-helix DNA binding domain and conserved cysteine residue suggests this type of redox signaling mechanism is widespread in Archaea.
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6
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Reconstruction and analysis of transcriptome regulatory network of Methanobrevibacter ruminantium M1. GENE REPORTS 2022. [DOI: 10.1016/j.genrep.2021.101489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Vershinin Z, Zaretsky M, Guan Z, Eichler J. Identifying Components of a Halobacterium salinarum N-Glycosylation Pathway. Front Microbiol 2021; 12:779599. [PMID: 34925283 PMCID: PMC8674786 DOI: 10.3389/fmicb.2021.779599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 10/27/2021] [Indexed: 11/13/2022] Open
Abstract
Whereas N-glycosylation is a seemingly universal process in Archaea, pathways of N-glycosylation have only been experimentally verified in a mere handful of species. Toward expanding the number of delineated archaeal N-glycosylation pathways, the involvement of the putative Halobacterium salinarum glycosyltransferases VNG1067G, VNG1066C, and VNG1062G in the assembly of an N-linked tetrasaccharide decorating glycoproteins in this species was addressed. Following deletion of each encoding gene, the impact on N-glycosylation of the S-layer glycoprotein and archaellins, major glycoproteins in this organism, was assessed by mass spectrometry. Likewise, the pool of dolichol phosphate, the lipid upon which this glycan is assembled, was also considered in each deletion strain. Finally, the impacts of such deletions were characterized in a series of biochemical, structural and physiological assays. The results revealed that VNG1067G, VNG1066C, and VNG1062G, renamed Agl25, Agl26, and Agl27 according to the nomenclature used for archaeal N-glycosylation pathway components, are responsible for adding the second, third and fourth sugars of the N-linked tetrasaccharide decorating Hbt. salinarum glycoproteins. Moreover, this study demonstrated how compromised N-glycosylation affects various facets of Hbt. salinarum cell behavior, including the transcription of archaellin-encoding genes.
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Affiliation(s)
- Zlata Vershinin
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Marianna Zaretsky
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel
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8
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Midani FS, Collins J, Britton RA. AMiGA: Software for Automated Analysis of Microbial Growth Assays. mSystems 2021; 6:e0050821. [PMID: 34254821 PMCID: PMC8409736 DOI: 10.1128/msystems.00508-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/16/2021] [Indexed: 12/18/2022] Open
Abstract
The analysis of microbial growth is one of the central methods in the field of microbiology. Microbial growth dynamics can be characterized by meaningful parameters, including carrying capacity, exponential growth rate, and growth lag. However, microbial assays with clinical isolates, fastidious organisms, or microbes under stress often produce atypical growth shapes that do not follow the classical microbial growth pattern. Here, we introduce the analysis of microbial growth assays (AMiGA) software, which streamlines the analysis of growth curves without any assumptions about their shapes. AMiGA can pool replicates of growth curves and infer summary statistics for biologically meaningful growth parameters. In addition, AMiGA can quantify death phases and characterize diauxic shifts. It can also statistically test for differential growth under distinct experimental conditions. Altogether, AMiGA streamlines the organization, analysis, and visualization of microbial growth assays. IMPORTANCE Our current understanding of microbial physiology relies on the simple method of measuring microbial populations' sizes over time and under different conditions. Many advances have increased the throughput of those assays and enabled the study of nonlab-adapted microbes under diverse conditions that widely affect their growth dynamics. Our software provides an all-in-one tool for estimating the growth parameters of microbial cultures and testing for differential growth in a high-throughput and user-friendly fashion without any underlying assumptions about how microbes respond to their growth conditions.
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Affiliation(s)
- Firas S. Midani
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
| | - James Collins
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
| | - Robert A. Britton
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
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9
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Grünberger F, Reichelt R, Waege I, Ned V, Bronner K, Kaljanac M, Weber N, El Ahmad Z, Knauss L, Madej MG, Ziegler C, Grohmann D, Hausner W. CopR, a Global Regulator of Transcription to Maintain Copper Homeostasis in Pyrococcus furiosus. Front Microbiol 2021; 11:613532. [PMID: 33505379 PMCID: PMC7830388 DOI: 10.3389/fmicb.2020.613532] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/09/2020] [Indexed: 11/24/2022] Open
Abstract
Although copper is in many cases an essential micronutrient for cellular life, higher concentrations are toxic. Therefore, all living cells have developed strategies to maintain copper homeostasis. In this manuscript, we have analyzed the transcriptome-wide response of Pyrococcus furiosus to increased copper concentrations and described the essential role of the putative copper-sensing metalloregulator CopR in the detoxification process. To this end, we employed biochemical and biophysical methods to characterize the role of CopR. Additionally, a copR knockout strain revealed an amplified sensitivity in comparison to the parental strain towards increased copper levels, which designates an essential role of CopR for copper homeostasis. To learn more about the CopR-regulated gene network, we performed differential gene expression and ChIP-seq analysis under normal and 20 μM copper-shock conditions. By integrating the transcriptome and genome-wide binding data, we found that CopR binds to the upstream regions of many copper-induced genes. Negative-stain transmission electron microscopy and 2D class averaging revealed an octameric assembly formed from a tetramer of dimers for CopR, similar to published crystal structures from the Lrp family. In conclusion, we propose a model for CopR-regulated transcription and highlight the regulatory network that enables Pyrococcus to respond to increased copper concentrations.
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Affiliation(s)
- Felix Grünberger
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Robert Reichelt
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Ingrid Waege
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Verena Ned
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Korbinian Bronner
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Marcell Kaljanac
- Department of Structural Biology, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Regensburg, Germany
| | - Nina Weber
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Zubeir El Ahmad
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Lena Knauss
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - M. Gregor Madej
- Department of Structural Biology, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Regensburg, Germany
| | - Christine Ziegler
- Department of Structural Biology, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Regensburg, Germany
| | - Dina Grohmann
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
| | - Winfried Hausner
- Institute of Microbiology and Archaea Centre, University of Regensburg, Regensburg, Germany
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10
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Tonner PD, Darnell CL, Bushell FML, Lund PA, Schmid AK, Schmidler SC. A Bayesian non-parametric mixed-effects model of microbial growth curves. PLoS Comput Biol 2020; 16:e1008366. [PMID: 33104703 PMCID: PMC7644099 DOI: 10.1371/journal.pcbi.1008366] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 11/05/2020] [Accepted: 08/30/2020] [Indexed: 11/19/2022] Open
Abstract
Substantive changes in gene expression, metabolism, and the proteome are manifested in overall changes in microbial population growth. Quantifying how microbes grow is therefore fundamental to areas such as genetics, bioengineering, and food safety. Traditional parametric growth curve models capture the population growth behavior through a set of summarizing parameters. However, estimation of these parameters from data is confounded by random effects such as experimental variability, batch effects or differences in experimental material. A systematic statistical method to identify and correct for such confounding effects in population growth data is not currently available. Further, our previous work has demonstrated that parametric models are insufficient to explain and predict microbial response under non-standard growth conditions. Here we develop a hierarchical Bayesian non-parametric model of population growth that identifies the latent growth behavior and response to perturbation, while simultaneously correcting for random effects in the data. This model enables more accurate estimates of the biological effect of interest, while better accounting for the uncertainty due to technical variation. Additionally, modeling hierarchical variation provides estimates of the relative impact of various confounding effects on measured population growth.
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Affiliation(s)
- Peter D. Tonner
- Program in Computational Biology and Bioinformatics, Duke University, Durham, NC, USA
- Biology Department, Duke University, Durham, NC, USA
| | | | - Francesca M. L. Bushell
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Peter A. Lund
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Amy K. Schmid
- Program in Computational Biology and Bioinformatics, Duke University, Durham, NC, USA
- Biology Department, Duke University, Durham, NC, USA
- Center for Computational Biology and Bioinformatics, Duke University, Durham, NC, USA
| | - Scott C. Schmidler
- Program in Computational Biology and Bioinformatics, Duke University, Durham, NC, USA
- Department of Statistical Science, Duke University, Durham, USA
- Department of Computer Science, Duke University, Durham, USA
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11
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Wenck BR, Santangelo TJ. Archaeal transcription. Transcription 2020; 11:199-210. [PMID: 33112729 PMCID: PMC7714419 DOI: 10.1080/21541264.2020.1838865] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 12/15/2022] Open
Abstract
Increasingly sophisticated biochemical and genetic techniques are unraveling the regulatory factors and mechanisms that control gene expression in the Archaea. While some similarities in regulatory strategies are universal, archaeal-specific regulatory strategies are emerging to complement a complex patchwork of shared archaeal-bacterial and archaeal-eukaryotic regulatory mechanisms employed in the archaeal domain. The prokaryotic archaea encode core transcription components with homology to the eukaryotic transcription apparatus and also share a simplified eukaryotic-like initiation mechanism, but also deploy tactics common to bacterial systems to regulate promoter usage and influence elongation-termination decisions. We review the recently established complete archaeal transcription cycle, highlight recent findings of the archaeal transcription community and detail the expanding post-initiation regulation imposed on archaeal transcription.
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Affiliation(s)
- Breanna R. Wenck
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Thomas J. Santangelo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
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12
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Darnell CL, Zheng J, Wilson S, Bertoli RM, Bisson-Filho AW, Garner EC, Schmid AK. The Ribbon-Helix-Helix Domain Protein CdrS Regulates the Tubulin Homolog ftsZ2 To Control Cell Division in Archaea. mBio 2020; 11:e01007-20. [PMID: 32788376 PMCID: PMC7439475 DOI: 10.1128/mbio.01007-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/06/2020] [Indexed: 11/24/2022] Open
Abstract
Precise control of the cell cycle is central to the physiology of all cells. In prior work we demonstrated that archaeal cells maintain a constant size; however, the regulatory mechanisms underlying the cell cycle remain unexplored in this domain of life. Here, we use genetics, functional genomics, and quantitative imaging to identify and characterize the novel CdrSL gene regulatory network in a model species of archaea. We demonstrate the central role of these ribbon-helix-helix family transcription factors in the regulation of cell division through specific transcriptional control of the gene encoding FtsZ2, a putative tubulin homolog. Using time-lapse fluorescence microscopy in live cells cultivated in microfluidics devices, we further demonstrate that FtsZ2 is required for cell division but not elongation. The cdrS-ftsZ2 locus is highly conserved throughout the archaeal domain, and the central function of CdrS in regulating cell division is conserved across hypersaline adapted archaea. We propose that the CdrSL-FtsZ2 transcriptional network coordinates cell division timing with cell growth in archaea.IMPORTANCE Healthy cell growth and division are critical for individual organism survival and species long-term viability. However, it remains unknown how cells of the domain Archaea maintain a healthy cell cycle. Understanding the archaeal cell cycle is of paramount evolutionary importance given that an archaeal cell was the host of the endosymbiotic event that gave rise to eukaryotes. Here, we identify and characterize novel molecular players needed for regulating cell division in archaea. These molecules dictate the timing of cell septation but are dispensable for growth between divisions. Timing is accomplished through transcriptional control of the cell division ring. Our results shed light on mechanisms underlying the archaeal cell cycle, which has thus far remained elusive.
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Affiliation(s)
| | - Jenny Zheng
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Sean Wilson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Ryan M Bertoli
- Biology Department, Duke University, Durham, North Carolina, USA
| | - Alexandre W Bisson-Filho
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Amy K Schmid
- Biology Department, Duke University, Durham, North Carolina, USA
- Center for Genomics and Computational Biology, Duke University, Durham, North Carolina, USA
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13
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Prathiviraj R, Chellapandi P. Modeling a global regulatory network of Methanothermobacter thermautotrophicus strain ∆H. ACTA ACUST UNITED AC 2020. [DOI: 10.1007/s13721-020-0223-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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14
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Watson A, Habib M, Bapteste E. Phylosystemics: Merging Phylogenomics, Systems Biology, and Ecology to Study Evolution. Trends Microbiol 2020; 28:176-190. [DOI: 10.1016/j.tim.2019.10.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 11/28/2022]
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15
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Hwang S, Chavarria NE, Hackley RK, Schmid AK, Maupin-Furlow JA. Gene Expression of Haloferax volcanii on Intermediate and Abundant Sources of Fixed Nitrogen. Int J Mol Sci 2019; 20:ijms20194784. [PMID: 31561502 PMCID: PMC6801745 DOI: 10.3390/ijms20194784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 09/20/2019] [Indexed: 12/17/2022] Open
Abstract
Haloferax volcanii, a well-developed model archaeon for genomic, transcriptomic, and proteomic analyses, can grow on a defined medium of abundant and intermediate levels of fixed nitrogen. Here we report a global profiling of gene expression of H. volcanii grown on ammonium as an abundant source of fixed nitrogen compared to l-alanine, the latter of which exemplifies an intermediate source of nitrogen that can be obtained from dead cells in natural habitats. By comparing the two growth conditions, 30 genes were found to be differentially expressed, including 16 genes associated with amino acid metabolism and transport. The gene expression profiles contributed to mapping ammonium and l-alanine usage with respect to transporters and metabolic pathways. In addition, conserved DNA motifs were identified in the putative promoter regions and transcription factors were found to be in synteny with the differentially expressed genes, leading us to propose regulons of transcriptionally co-regulated operons. This study provides insight to how H. volcanii responds to and utilizes intermediate vs. abundant sources of fixed nitrogen for growth, with implications for conserved functions in related halophilic archaea.
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Affiliation(s)
- Sungmin Hwang
- Department of Biology, Duke University, Durham, NC 27708, USA.
| | - Nikita E Chavarria
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
| | - Rylee K Hackley
- Department of Biology, Duke University, Durham, NC 27708, USA.
- University Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA.
| | - Amy K Schmid
- Department of Biology, Duke University, Durham, NC 27708, USA.
- University Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA.
- Center for Genomics and Computational Biology, Duke University, Duke University, Durham, NC 27708, USA.
| | - Julie A Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
- Genetics Institute, University of Florida, Gainesville, FL 32611, USA.
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16
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Hackley RK, Schmid AK. Global Transcriptional Programs in Archaea Share Features with the Eukaryotic Environmental Stress Response. J Mol Biol 2019; 431:4147-4166. [PMID: 31437442 PMCID: PMC7419163 DOI: 10.1016/j.jmb.2019.07.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/18/2019] [Accepted: 07/18/2019] [Indexed: 01/06/2023]
Abstract
The environmental stress response (ESR), a global transcriptional program originally identified in yeast, is characterized by a rapid and transient transcriptional response composed of large, oppositely regulated gene clusters. Genes induced during the ESR encode core components of stress tolerance, macromolecular repair, and maintenance of homeostasis. In this review, we investigate the possibility for conservation of the ESR across the eukaryotic and archaeal domains of life. We first re-analyze existing transcriptomics data sets to illustrate that a similar transcriptional response is identifiable in Halobacterium salinarum, an archaeal model organism. To substantiate the archaeal ESR, we calculated gene-by-gene correlations, gene function enrichment, and comparison of temporal dynamics. We note reported examples of variation in the ESR across fungi, then synthesize high-level trends present in expression data of other archaeal species. In particular, we emphasize the need for additional high-throughput time series expression data to further characterize stress-responsive transcriptional programs in the Archaea. Together, this review explores an open question regarding features of global transcriptional stress response programs shared across domains of life.
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Affiliation(s)
- Rylee K Hackley
- Department of Biology, Duke University, Durham, NC 27708, USA; University Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA
| | - Amy K Schmid
- Department of Biology, Duke University, Durham, NC 27708, USA; University Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA; Center for Genomics and Computational Biology, Duke University, Durham, NC 27708, USA.
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17
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Zaretsky M, Darnell CL, Schmid AK, Eichler J. N-Glycosylation Is Important for Halobacterium salinarum Archaellin Expression, Archaellum Assembly and Cell Motility. Front Microbiol 2019; 10:1367. [PMID: 31275283 PMCID: PMC6591318 DOI: 10.3389/fmicb.2019.01367] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 05/31/2019] [Indexed: 12/20/2022] Open
Abstract
Halobacterium salinarum are halophilic archaea that display directional swimming in response to various environmental signals, including light, chemicals and oxygen. In Hbt. salinarum, the building blocks (archaellins) of the archaeal swimming apparatus (the archaellum) are N-glycosylated. However, the physiological importance of archaellin N-glycosylation remains unclear. Here, a tetrasaccharide comprising a hexose and three hexuronic acids decorating the five archaellins was characterized by mass spectrometry. Such analysis failed to detect sulfation of the hexuronic acids, in contrast to earlier reports. To better understand the physiological significance of Hbt. salinarum archaellin N-glycosylation, a strain deleted of aglB, encoding the archaeal oligosaccharyltransferase, was generated. In this ΔaglB strain, archaella were not detected and only low levels of archaellins were released into the medium, in contrast to what occurs with the parent strain. Mass spectrometry analysis of the archaellins in ΔaglB cultures did not detect N-glycosylation. ΔaglB cells also showed a slight growth defect and were impaired for motility. Quantitative real-time PCR analysis revealed dramatically reduced transcript levels of archaellin-encoding genes in the mutant strain, suggesting that N-glycosylation is important for archaellin transcription, with downstream effects on archaellum assembly and function. Control of AglB-dependent post-translational modification of archaellins could thus reflect a previously unrecognized route for regulating Hbt. salinarum motility.
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Affiliation(s)
- Marianna Zaretsky
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheba, Israel
| | | | - Amy K Schmid
- Department of Biology, Duke University, Durham, NC, United States.,Center for Genomics and Computational Biology, Duke University, Durham, NC, United States
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheba, Israel
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18
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Characterization of the transcriptome of Haloferax volcanii, grown under four different conditions, with mixed RNA-Seq. PLoS One 2019; 14:e0215986. [PMID: 31039177 PMCID: PMC6490895 DOI: 10.1371/journal.pone.0215986] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 04/11/2019] [Indexed: 12/21/2022] Open
Abstract
Haloferax volcanii is a well-established model species for haloarchaea. Small scale RNomics and bioinformatics predictions were used to identify small non-coding RNAs (sRNAs), and deletion mutants revealed that sRNAs have important regulatory functions. A recent dRNA-Seq study was used to characterize the primary transcriptome. Unexpectedly, it was revealed that, under optimal conditions, H. volcanii contains more non-coding sRNAs than protein-encoding mRNAs. However, the dRNA-Seq approach did not contain any length information. Therefore, a mixed RNA-Seq approach was used to determine transcript length and to identify additional transcripts, which are not present under optimal conditions. In total, 50 million paired end reads of 150 nt length were obtained. 1861 protein-coding RNAs (cdRNAs) were detected, which encoded 3092 proteins. This nearly doubled the coverage of cdRNAs, compared to the previous dRNA-Seq study. About 2/3 of the cdRNAs were monocistronic, and 1/3 covered more than one gene. In addition, 1635 non-coding sRNAs were identified. The highest fraction of non-coding RNAs were cis antisense RNAs (asRNAs). Analysis of the length distribution revealed that sRNAs have a median length of about 150 nt. Based on the RNA-Seq and dRNA-Seq results, genes were chosen to exemplify characteristics of the H. volcanii transcriptome by Northern blot analyses, e.g. 1) the transcript patterns of gene clusters can be straightforward, but also very complex, 2) many transcripts differ in expression level under the four analyzed conditions, 3) some genes are transcribed into RNA isoforms of different length, which can be differentially regulated, 4) transcripts with very long 5'-UTRs and with very long 3'-UTRs exist, and 5) about 30% of all cdRNAs have overlapping 3'-ends, which indicates, together with the asRNAs, that H. volcanii makes ample use of sense-antisense interactions. Taken together, this RNA-Seq study, together with a previous dRNA-Seq study, enabled an unprecedented view on the H. volcanii transcriptome.
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19
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Bushell FML, Tonner PD, Jabbari S, Schmid AK, Lund PA. Synergistic Impacts of Organic Acids and pH on Growth of Pseudomonas aeruginosa: A Comparison of Parametric and Bayesian Non-parametric Methods to Model Growth. Front Microbiol 2019; 9:3196. [PMID: 30671033 PMCID: PMC6331447 DOI: 10.3389/fmicb.2018.03196] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 12/10/2018] [Indexed: 01/05/2023] Open
Abstract
Different weak organic acids have significant potential as topical treatments for wounds infected by opportunistic pathogens that are recalcitrant to standard treatments. These acids have long been used as bacteriostatic compounds in the food industry, and in some cases are already being used in the clinic. The effects of different organic acids vary with pH, concentration, and the specific organic acid used, but no studies to date on any opportunistic pathogens have examined the detailed interactions between these key variables in a controlled and systematic way. We have therefore comprehensively evaluated the effects of several different weak organic acids on growth of the opportunistic pathogen Pseudomonas aeruginosa. We used a semi-automated plate reader to generate growth profiles for two different strains (model laboratory strain PAO1 and clinical isolate PA1054 from a hospital burns unit) in a range of organic acids at different concentrations and pH, with a high level of replication for a total of 162,960 data points. We then compared two different modeling approaches for the interpretation of this time-resolved dataset: parametric logistic regression (with or without a component to include lag phase) vs. non-parametric Gaussian process (GP) regression. Because GP makes no prior assumptions about the nature of the growth, this method proved to be superior in cases where growth did not follow a standard sigmoid functional form, as is common when bacteria grow under stress. Acetic, propionic and butyric acids were all more detrimental to growth than the other acids tested, and although PA1054 grew better than PAO1 under non-stress conditions, this difference largely disappeared as the levels of stress increased. As expected from knowledge of how organic acids behave, their effect was significantly enhanced in combination with low pH, with this interaction being greatest in the case of propionic acid. Our approach lends itself to the characterization of combinatorial interactions between stressors, especially in cases where their impacts on growth render logistic growth models unsuitable.
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Affiliation(s)
- Francesca M. L. Bushell
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Peter D. Tonner
- Department of Biology, Duke University, Durham, NC, United States
- Statistical Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, United States
| | - Sara Jabbari
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
- School of Mathematics, University of Birmingham, Birmingham, United Kingdom
| | - Amy K. Schmid
- Department of Biology, Duke University, Durham, NC, United States
- Center for Genomics and Computational Biology, Duke University, Durham, NC, United States
| | - Peter A. Lund
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
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20
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Stochasticity in transcriptional expression of a negative regulator of Arabidopsis ABA network. 3 Biotech 2019; 9:15. [PMID: 30622853 DOI: 10.1007/s13205-018-1542-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/16/2018] [Indexed: 10/27/2022] Open
Abstract
Stably heritable spatiotemporal co/over-expression of distinct transcriptional regulators across generations is a desired target as they signal traffic in the cell. Here, the stability and expression pattern of AtHB7 (Arabidopsis homeodomain-leucine zipper class I) cDNA was characterized in 220 random population of transformed tomato clones where no AtHB7 orthologous has been identified in to date. Integration of p35S::AtHB7 casette was tested by the amplification of the stretches (700/425 bp) in the target by NPT II/AtHB7 oligos. Transcriptional expression pattern for the amplicons of the specific transcripts in the leaf tissues of transformants were determined by qRT-PCR. Transgene copy number was negatively correlated with transgene expression level, yet a majority of transformants (78%) carried single-copy of transgene. About 1:3 of the lines containing two-copy inserts showed less transcript expression. Heterologous CaMV 35S promoter drove AtHB7, illuminated no penalty on transgene expression levels, stability or plant phenotype under drought stress. Integration and expression analysis of transcription factors is of great significance for reliable prediction of gene dosing/functions in plant genomes so as to sustain breeding under abiotic stress to guarantee food security.
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21
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Heat shock response in archaea. Emerg Top Life Sci 2018; 2:581-593. [DOI: 10.1042/etls20180024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 10/10/2018] [Accepted: 10/23/2018] [Indexed: 11/17/2022]
Abstract
An adequate response to a sudden temperature rise is crucial for cellular fitness and survival. While heat shock response (HSR) is well described in bacteria and eukaryotes, much less information is available for archaea, of which many characterized species are extremophiles thriving in habitats typified by large temperature gradients. Here, we describe known molecular aspects of archaeal heat shock proteins (HSPs) as key components of the protein homeostasis machinery and place this in a phylogenetic perspective with respect to bacterial and eukaryotic HSPs. Particular emphasis is placed on structure–function details of the archaeal thermosome, which is a major element of the HSR and of which subunit composition is altered in response to temperature changes. In contrast with the structural response, it is largely unclear how archaeal cells sense temperature fluctuations and which molecular mechanisms underlie the corresponding regulation. We frame this gap in knowledge by discussing emerging questions related to archaeal HSR and by proposing methodologies to address them. Additionally, as has been shown in bacteria and eukaryotes, HSR is expected to be relevant for the control of physiology and growth in various stress conditions beyond temperature stress. A better understanding of this essential cellular process in archaea will not only provide insights into the evolution of HSR and of its sensing and regulation, but also inspire the development of biotechnological applications, by enabling transfer of archaeal heat shock components to other biological systems and for the engineering of archaea as robust cell factories.
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22
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Dulmage KA, Darnell CL, Vreugdenhil A, Schmid AK. Copy number variation is associated with gene expression change in archaea. Microb Genom 2018; 4. [PMID: 30142055 PMCID: PMC6202454 DOI: 10.1099/mgen.0.000210] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Genomic instability, although frequently deleterious, is also an important mechanism for microbial adaptation to environmental change. Although widely studied in bacteria, in archaea the effect of genomic instability on organism phenotypes and fitness remains unclear. Here we use DNA segmentation methods to detect and quantify genome-wide copy number variation (CNV) in large compendia of high-throughput datasets in a model archaeal species, Halobacterium salinarum. CNV hotspots were identified throughout the genome. Some hotspots were strongly associated with changes in gene expression, suggesting a mechanism for phenotypic innovation. In contrast, CNV hotspots in other genomic loci left expression unchanged, suggesting buffering of certain phenotypes. The correspondence of CNVs with gene expression was validated with strain- and condition-matched transcriptomics and DNA quantification experiments at specific loci. Significant correlation of CNV hotspot locations with the positions of known insertion sequence (IS) elements suggested a mechanism for generating genomic instability. Given the efficient recombination capabilities in H. salinarum despite stability at the single nucleotide level, these results suggest that genomic plasticity mediated by IS element activity can provide a source of phenotypic innovation in extreme environments.
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Affiliation(s)
- Keely A Dulmage
- 1University Program in Genetics and Genomics, Duke University, Durham, NC, USA.,2Biology Department, Duke University, Durham, NC, USA
| | | | | | - Amy K Schmid
- 1University Program in Genetics and Genomics, Duke University, Durham, NC, USA.,2Biology Department, Duke University, Durham, NC, USA.,3Center for Genomics and Computational Biology, Duke University, Durham, NC 27708, USA
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23
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Martinez-Pastor M, Tonner PD, Darnell CL, Schmid AK. Transcriptional Regulation in Archaea: From Individual Genes to Global Regulatory Networks. Annu Rev Genet 2018; 51:143-170. [PMID: 29178818 DOI: 10.1146/annurev-genet-120116-023413] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Archaea are major contributors to biogeochemical cycles, possess unique metabolic capabilities, and resist extreme stress. To regulate the expression of genes encoding these unique programs, archaeal cells use gene regulatory networks (GRNs) composed of transcription factor proteins and their target genes. Recent developments in genetics, genomics, and computational methods used with archaeal model organisms have enabled the mapping and prediction of global GRN structures. Experimental tests of these predictions have revealed the dynamical function of GRNs in response to environmental variation. Here, we review recent progress made in this area, from investigating the mechanisms of transcriptional regulation of individual genes to small-scale subnetworks and genome-wide global networks. At each level, archaeal GRNs consist of a hybrid of bacterial, eukaryotic, and uniquely archaeal mechanisms. We discuss this theme from the perspective of the role of individual transcription factors in genome-wide regulation, how these proteins interact to compile GRN topological structures, and how these topologies lead to emergent, high-level GRN functions. We conclude by discussing how systems biology approaches are a fruitful avenue for addressing remaining challenges, such as discovering gene function and the evolution of GRNs.
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Affiliation(s)
| | - Peter D Tonner
- Department of Biology, Duke University, Durham, North Carolina 27708, USA.,Graduate Program in Computational Biology and Bioinformatics, Duke University, Durham, North Carolina 27708, USA
| | - Cynthia L Darnell
- Department of Biology, Duke University, Durham, North Carolina 27708, USA
| | - Amy K Schmid
- Department of Biology, Duke University, Durham, North Carolina 27708, USA.,Graduate Program in Computational Biology and Bioinformatics, Duke University, Durham, North Carolina 27708, USA.,Center for Genomic and Computational Biology, Duke University, Durham, North Carolina 27708, USA;
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