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Guiza Beltran D, Wan T, Zhang L. WhiB-like proteins: Diversity of structure, function and mechanism. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119787. [PMID: 38879133 PMCID: PMC11365794 DOI: 10.1016/j.bbamcr.2024.119787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/20/2024] [Accepted: 06/11/2024] [Indexed: 06/22/2024]
Abstract
The WhiB-Like (Wbl) proteins are a large family of iron-sulfur (Fe-S) cluster-containing transcription factors exclusively found in the phylum Actinobacteria, including the notable genera like Mycobacteria, Streptomycetes and Corynebacteria. These proteins play pivotal roles in diverse biological processes, such as cell development, redox stress response and antibiotic resistance. Members of the Wbl family exhibit remarkable diversity in their sequences, structures and functions, attracting great attention since their first discovery. This review highlights the most recent breakthroughs in understanding the structural and mechanistic aspects of Wbl-dependent transcriptional regulation.
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Affiliation(s)
- Daisy Guiza Beltran
- Department of Biochemistry, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA
| | - Tao Wan
- Department of Biochemistry, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA
| | - LiMei Zhang
- Department of Biochemistry, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA; Redox Biology Center, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA; Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA.
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2
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Bohorquez LC, de Sousa J, Garcia-Garcia T, Dugar G, Wang B, Jonker MJ, Noirot-Gros MF, Lalk M, Hamoen LW. Metabolic and chromosomal changes in a Bacillus subtilis whiA mutant. Microbiol Spectr 2023; 11:e0179523. [PMID: 37916812 PMCID: PMC10714963 DOI: 10.1128/spectrum.01795-23] [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: 04/28/2023] [Accepted: 10/10/2023] [Indexed: 11/03/2023] Open
Abstract
IMPORTANCE WhiA is a conserved DNA-binding protein that influences cell division in many Gram-positive bacteria and, in B. subtilis, also chromosome segregation. How WhiA works in Bacillus subtilis is unknown. Here, we tested three hypothetical mechanisms using metabolomics, fatty acid analysis, and chromosome confirmation capture experiments. This revealed that WhiA does not influence cell division and chromosome segregation by modulating either central carbon metabolism or fatty acid composition. However, the inactivation of WhiA reduces short-range chromosome interactions. These findings provide new avenues to study the molecular mechanism of WhiA in the future.
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Affiliation(s)
- Laura C. Bohorquez
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Joana de Sousa
- Institute of Biochemistry, University of Greifswald, Greifswald, Germany
| | - Transito Garcia-Garcia
- Laboratoire de Genetique Microbienne, Domaine de Vilvert, Institut National de la Recherche Agronomique, Jouy-en-Josas, France
| | - Gaurav Dugar
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Biwen Wang
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Martijs J. Jonker
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Marie-Françoise Noirot-Gros
- Laboratoire de Genetique Microbienne, Domaine de Vilvert, Institut National de la Recherche Agronomique, Jouy-en-Josas, France
| | - Michael Lalk
- Institute of Biochemistry, University of Greifswald, Greifswald, Germany
| | - Leendert W. Hamoen
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
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3
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Lilic M, Holmes NA, Bush MJ, Marti AK, Widdick DA, Findlay KC, Choi YJ, Froom R, Koh S, Buttner MJ, Campbell EA. Structural basis of dual activation of cell division by the actinobacterial transcription factors WhiA and WhiB. Proc Natl Acad Sci U S A 2023; 120:e2220785120. [PMID: 36888660 PMCID: PMC10243135 DOI: 10.1073/pnas.2220785120] [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: 12/06/2022] [Accepted: 01/26/2023] [Indexed: 03/09/2023] Open
Abstract
Studies of transcriptional initiation in different bacterial clades reveal diverse molecular mechanisms regulating this first step in gene expression. The WhiA and WhiB factors are both required to express cell division genes in Actinobacteria and are essential in notable pathogens such as Mycobacterium tuberculosis. The WhiA/B regulons and binding sites have been elucidated in Streptomyces venezuelae (Sven), where they coordinate to activate sporulation septation. However, how these factors cooperate at the molecular level is not understood. Here we present cryoelectron microscopy structures of Sven transcriptional regulatory complexes comprising RNA polymerase (RNAP) σA-holoenzyme and WhiA and WhiB, in complex with the WhiA/B target promoter sepX. These structures reveal that WhiB binds to domain 4 of σA (σA4) of the σA-holoenzyme, bridging an interaction with WhiA while making non-specific contacts with the DNA upstream of the -35 core promoter element. The N-terminal homing endonuclease-like domain of WhiA interacts with WhiB, while the WhiA C-terminal domain (WhiA-CTD) makes base-specific contacts with the conserved WhiA GACAC motif. Notably, the structure of the WhiA-CTD and its interactions with the WhiA motif are strikingly similar to those observed between σA4 housekeeping σ-factors and the -35 promoter element, suggesting an evolutionary relationship. Structure-guided mutagenesis designed to disrupt these protein-DNA interactions reduces or abolishes developmental cell division in Sven, confirming their significance. Finally, we compare the architecture of the WhiA/B σA-holoenzyme promoter complex with the unrelated but model CAP Class I and Class II complexes, showing that WhiA/WhiB represent a new mechanism in bacterial transcriptional activation.
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Affiliation(s)
- Mirjana Lilic
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - Neil A. Holmes
- Department of Molecular Microbiology, John Innes Centre, NorwichNR4 7UH, UK
| | - Matthew J. Bush
- Department of Molecular Microbiology, John Innes Centre, NorwichNR4 7UH, UK
| | - Alexandra K. Marti
- Department of Molecular Microbiology, John Innes Centre, NorwichNR4 7UH, UK
| | - David A. Widdick
- Department of Molecular Microbiology, John Innes Centre, NorwichNR4 7UH, UK
| | - Kim C. Findlay
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, UK
| | - Young Joo Choi
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - Ruby Froom
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - Steven Koh
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - Mark J. Buttner
- Department of Molecular Microbiology, John Innes Centre, NorwichNR4 7UH, UK
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Centeno-Leija S, Espinosa-Barrera L, Velazquez-Cruz B, Cárdenas-Conejo Y, Virgen-Ortíz R, Valencia-Cruz G, Saenz RA, Marín-Tovar Y, Gómez-Manzo S, Hernández-Ochoa B, Rocha-Ramirez LM, Zataraín-Palacios R, Osuna-Castro JA, López-Munguía A, Serrano-Posada H. Mining for novel cyclomaltodextrin glucanotransferases unravels the carbohydrate metabolism pathway via cyclodextrins in Thermoanaerobacterales. Sci Rep 2022; 12:730. [PMID: 35031648 PMCID: PMC8760340 DOI: 10.1038/s41598-021-04569-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/20/2021] [Indexed: 11/21/2022] Open
Abstract
Carbohydrate metabolism via cyclodextrins (CM-CD) is an uncommon starch-converting pathway that thoroughly depends on extracellular cyclomaltodextrin glucanotransferases (CGTases) to transform the surrounding starch substrate to α-(1,4)-linked oligosaccharides and cyclodextrins (CDs). The CM-CD pathway has emerged as a convenient microbial adaptation to thrive under extreme temperatures, as CDs are functional amphipathic toroids with higher heat-resistant values than linear dextrins. Nevertheless, although the CM-CD pathway has been described in a few mesophilic bacteria and archaea, it remains obscure in extremely thermophilic prokaryotes (Topt ≥ 70 °C). Here, a new monophyletic group of CGTases with an exceptional three-domain ABC architecture was detected by (meta)genome mining of extremely thermophilic Thermoanaerobacterales living in a wide variety of hot starch-poor environments on Earth. Functional studies of a representative member, CldA, showed a maximum activity in a thermoacidophilic range (pH 4.0 and 80 °C) with remarkable product diversification that yielded a mixture of α:β:γ-CDs (34:62:4) from soluble starch, as well as G3-G7 linear dextrins and fermentable sugars as the primary products. Together, comparative genomics and predictive functional analysis, combined with data of the functionally characterized key proteins of the gene clusters encoding CGTases, revealed the CM-CD pathway in Thermoanaerobacterales and showed that it is involved in the synthesis, transportation, degradation, and metabolic assimilation of CDs.
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Affiliation(s)
- Sara Centeno-Leija
- Consejo Nacional de Ciencia y Tecnología, Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico.
| | - Laura Espinosa-Barrera
- Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Beatriz Velazquez-Cruz
- Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Yair Cárdenas-Conejo
- Consejo Nacional de Ciencia y Tecnología, Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Raúl Virgen-Ortíz
- Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico
| | - Georgina Valencia-Cruz
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Avenida 25 de julio 965, Colonia Villa de San Sebastián, 28045, Colima, Colima, Mexico
| | - Roberto A Saenz
- Facultad de Ciencias, Universidad de Colima, Bernal Díaz del Castillo 340, 28045, Colima, Colima, Mexico
| | - Yerli Marín-Tovar
- Laboratorio de Bioquímica Estructural, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210, Cuernavaca, Mexico
| | - Saúl Gómez-Manzo
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, 04530, Mexico City, Mexico
| | - Beatriz Hernández-Ochoa
- Laboratorio de Inmunoquímica y Biología Celular, Hospital Infantil de México Federico Gómez, Secretaría de Salud, 06720, Mexico City, Mexico
| | - Luz María Rocha-Ramirez
- Unidad de Investigación en Enfermedades Infecciosas, Hospital Infantil de México Federico Gómez, Dr. Márquez No. 162, Colonia Doctores, 06720, Delegación Cuauhtémoc, Mexico
| | - Rocío Zataraín-Palacios
- Escuela de Medicina General, Universidad José Martí, Bosques del Decán 351, 28089, Colima, Colima, México
| | - Juan A Osuna-Castro
- Facultad de Ciencias Biológicas y Agropecuarias, Universidad de Colima, Autopista Colima-Manzanillo, 28100, Tecomán, Colima, Mexico
| | - Agustín López-Munguía
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210, Cuernavaca, Morelos, Mexico
| | - Hugo Serrano-Posada
- Consejo Nacional de Ciencia y Tecnología, Laboratorio de Biología Sintética, Estructural y Molecular, Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera Los Limones-Loma de Juárez, 28627, Colima, Colima, Mexico.
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Jeong H, Lee JH, Kim Y, Lee HS. Thiol-specific oxidant diamide downregulates whiA gene of Corynebacterium glutamicum, thereby suppressing cell division and metabolism. Res Microbiol 2020; 171:331-340. [PMID: 32750493 DOI: 10.1016/j.resmic.2020.07.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 11/24/2022]
Abstract
The whiA (NCgl1527) gene from Corynebacterium glutamicum plays a crucial role during cell growth, and WhiA is recognized as the transcription factor for genes involved in cell division. In this study, we assessed the regulatory role of the gene in cell physiology. Transcription of the gene was specifically downregulated by the thiol-specific oxidant, diamide, and by heat stress. Cells exposed to diamide showed decreased transcription of genes involved in cell division and these effects were more profound in ΔwhiA cells. In addition, the ΔwhiA cells showed sensitivity to thiol-specific oxidants, DNA-damaging agents, and high temperature. Further, downregulation of sigH (NCgl0733), the central regulator in stress responses, along with master regulatory genes in cell metabolism, was observed in the ΔwhiA strain. Moreover, the amount of cAMP in the ΔwhiA cells in the early stationary phase was only at 30% level of that for the wild-type strain. Collectively, our data indicate that the role of whiA is to downregulate genes associated with cell division in response to heat or thiol-specific oxidative stress, and may suggest a role for the gene in downshifting cell metabolism by downregulating global regulatory genes when growth condition is not optimal for cells.
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Affiliation(s)
- Haeri Jeong
- Department of Biotechnology and Bioinformatics, Korea University, Sejong, Republic of Korea.
| | - Jae-Hyun Lee
- Department of Biotechnology and Bioinformatics, Korea University, Sejong, Republic of Korea.
| | - Younhee Kim
- Department of Korean Medicine, Semyung University, Jecheon, Chungbuk, Republic of Korea.
| | - Heung-Shick Lee
- Department of Biotechnology and Bioinformatics, Korea University, Sejong, Republic of Korea.
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Coughlan AY, Lombardi L, Braun-Galleani S, Martos AA, Galeote V, Bigey F, Dequin S, Byrne KP, Wolfe KH. The yeast mating-type switching endonuclease HO is a domesticated member of an unorthodox homing genetic element family. eLife 2020; 9:55336. [PMID: 32338594 PMCID: PMC7282813 DOI: 10.7554/elife.55336] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/24/2020] [Indexed: 01/07/2023] Open
Abstract
The mating-type switching endonuclease HO plays a central role in the natural life cycle of Saccharomyces cerevisiae, but its evolutionary origin is unknown. HO is a recent addition to yeast genomes, present in only a few genera close to Saccharomyces. Here we show that HO is structurally and phylogenetically related to a family of unorthodox homing genetic elements found in Torulaspora and Lachancea yeasts. These WHO elements home into the aldolase gene FBA1, replacing its 3' end each time they integrate. They resemble inteins but they operate by a different mechanism that does not require protein splicing. We show that a WHO protein cleaves Torulaspora delbrueckii FBA1 efficiently and in an allele-specific manner, leading to DNA repair by gene conversion or NHEJ. The DNA rearrangement steps during WHO element homing are very similar to those during mating-type switching, and indicate that HO is a domesticated WHO-like element. In the same way as a sperm from a male and an egg from a female join together to form an embryo in most animals, yeast cells have two sexes that coordinate how they reproduce. These are called “mating types” and, rather than male or female, an individual yeast cell can either be mating type “a” or “alpha”. Every yeast cell contains the genes for both mating types, and each cell’s mating type is determined by which of those genes it has active. Only one mating type gene can be ‘on’ at a time, but some yeast species can swap mating type on demand by switching the corresponding genes ‘on’ or ‘off’. This switch is unusual. Rather than simply activate one of the genes it already has, the yeast cell keeps an inactive version of each mating type gene tucked away, makes a copy of the gene it wants to be active and pastes that copy into a different location in its genome. To do all of this yeast need another gene called HO. This gene codes for an enzyme that cuts the DNA at the location of the active mating type gene. This makes an opening that allows the cell to replace the ‘a’ gene with the ‘alpha’ gene, or vice versa. This system allows yeast cells to continue mating even if all the cells in a colony start off as the same mating type. But, cutting into the DNA is risky, and can damage the health of the cell. So, why did yeast cells evolve a system that could cause them harm? To find out where the HO gene came from, Coughlan et al. searched through all the available genomes from yeast species for other genes with similar sequences and identified a cluster which they nicknamed “weird HO” genes, or WHO genes for short. Testing these genes revealed that they also code for enzymes that make cuts in the yeast genome, but the way the cell repairs the cuts is different. The WHO genes are jumping genes. When the enzyme encoded by a WHO gene makes a cut in the genome, the yeast cell copies the gene into the gap, allowing the gene to ‘jump’ from one part of the genome to another. It is possible that this was the starting point for the evolution of the HO gene. Changes to a WHO gene could have allowed it to cut into the mating type region of the yeast genome, giving the yeast an opportunity to ‘domesticate’ it. Over time, the yeast cell stopped the WHO gene from jumping into the gap and started using the cut to change its mating type. Understanding how cells adapt genes for different purposes is a key question in evolutionary biology. There are many other examples of domesticated jumping genes in other organisms, including in the human immune system. Understanding the evolution of HO not only sheds light on how yeast mating type switching evolved, but on how other species might harness and adapt their genes.
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Affiliation(s)
- Aisling Y Coughlan
- UCD Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
| | - Lisa Lombardi
- UCD Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
| | | | - Alexandre Ar Martos
- UCD Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
| | - Virginie Galeote
- SPO, INRAE, Université Montpellier, Montpellier SupAgro, Montpellier, France
| | - Frédéric Bigey
- SPO, INRAE, Université Montpellier, Montpellier SupAgro, Montpellier, France
| | - Sylvie Dequin
- SPO, INRAE, Université Montpellier, Montpellier SupAgro, Montpellier, France
| | - Kevin P Byrne
- UCD Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
| | - Kenneth H Wolfe
- UCD Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
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Lee JH, Jeong H, Kim Y, Lee HS. Corynebacterium glutamicum whiA plays roles in cell division, cell envelope formation, and general cell physiology. Antonie van Leeuwenhoek 2019; 113:629-641. [DOI: 10.1007/s10482-019-01370-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/30/2019] [Indexed: 10/25/2022]
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Abstract
SIGNIFICANCE Iron-sulfur cluster proteins carry out multiple functions, including as regulators of gene transcription/translation in response to environmental stimuli. In all known cases, the cluster acts as the sensory module, where the inherent reactivity/fragility of iron-sulfur clusters with small/redox-active molecules is exploited to effect conformational changes that modulate binding to DNA regulatory sequences. This promotes an often substantial reprogramming of the cellular proteome that enables the organism or cell to adapt to, or counteract, its changing circumstances. Recent Advances: Significant progress has been made recently in the structural and mechanistic characterization of iron-sulfur cluster regulators and, in particular, the O2 and NO sensor FNR, the NO sensor NsrR, and WhiB-like proteins of Actinobacteria. These are the main focus of this review. CRITICAL ISSUES Striking examples of how the local environment controls the cluster sensitivity and reactivity are now emerging, but the basis for this is not yet fully understood for any regulatory family. FUTURE DIRECTIONS Characterization of iron-sulfur cluster regulators has long been hampered by a lack of high-resolution structural data. Although this still presents a major future challenge, recent advances now provide a firm foundation for detailed understanding of how a signal is transduced to effect gene regulation. This requires the identification of often unstable intermediate species, which are difficult to detect and may be hard to distinguish using traditional techniques. Novel approaches will be required to solve these problems.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia , Norwich Research Park, Norwich, United Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia , Norwich Research Park, Norwich, United Kingdom
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Bush MJ. The actinobacterial WhiB-like (Wbl) family of transcription factors. Mol Microbiol 2018; 110:663-676. [PMID: 30179278 PMCID: PMC6282962 DOI: 10.1111/mmi.14117] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/29/2018] [Accepted: 08/30/2018] [Indexed: 02/06/2023]
Abstract
The WhiB‐like (Wbl) family of proteins are exclusively found in Actinobacteria. Wbls have been shown to play key roles in virulence and antibiotic resistance in Mycobacteria and Corynebacteria, reflecting their importance during infection by the human pathogens Mycobacterium tuberculosis, Mycobacterium leprae and Corynebacterium diphtheriae. In the antibiotic‐producing Streptomyces, several Wbls have important roles in the regulation of morphological differentiation, including WhiB, a protein that controls the initiation of sporulation septation and the founding member of the Wbl family. In recent years, genome sequencing has revealed the prevalence of Wbl paralogues in species throughout the Actinobacteria. Wbl proteins are small (generally ~80–140 residues) and each contains four invariant cysteine residues that bind an O2‐ and NO‐sensitive [4Fe–4S] cluster, raising the question as to how they can maintain distinct cellular functions within a given species. Despite their discovery over 25 years ago, the Wbl protein family has largely remained enigmatic. Here I summarise recent research in Mycobacteria, Corynebacteria and Streptomyces that sheds light on the biochemical function of Wbls as transcription factors and as potential sensors of O2 and NO. I suggest that Wbl evolution has created diversity in protein–protein interactions, [4Fe–4S] cluster‐sensitivity and the ability to bind DNA.
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Affiliation(s)
- Matthew J Bush
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
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10
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The Conserved DNA Binding Protein WhiA Influences Chromosome Segregation in Bacillus subtilis. J Bacteriol 2018; 200:JB.00633-17. [PMID: 29378890 DOI: 10.1128/jb.00633-17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/22/2018] [Indexed: 11/20/2022] Open
Abstract
The DNA binding protein WhiA is conserved in Gram-positive bacteria and is present in the genetically simple cell wall-lacking mycoplasmas. The protein shows homology to eukaryotic homing endonucleases but lacks nuclease activity. WhiA was first characterized in streptomycetes, where it regulates the expression of key differentiation genes, including the cell division gene ftsZ, which is essential for sporulation. For Bacillus subtilis, it was shown that WhiA is essential when certain cell division genes are deleted. However, in B. subtilis, WhiA is not required for sporulation, and it does not seem to function as a transcription factor, despite its DNA binding activity. The exact function of B. subtilis WhiA remains elusive. We noticed that whiA mutants show an increased space between their nucleoids, and here, we describe the results of fluorescence microscopy, genetic, and transcriptional experiments to further investigate this phenomenon. It appeared that the deletion of whiA is synthetic lethal when either the DNA replication and segregation regulator ParB or the DNA replication inhibitor YabA is absent. However, WhiA does not seem to affect replication initiation. We found that a ΔwhiA mutant is highly sensitive for DNA-damaging agents. Further tests revealed that the deletion of parAB induces the SOS response, including the cell division inhibitor YneA. When yneA was inactivated, the viability of the synthetic lethal ΔwhiA ΔparAB mutant was restored. However, the nucleoid segregation phenotype remained. These findings underline the importance of WhiA for cell division and indicate that the protein also plays a role in DNA segregation.IMPORTANCE The conserved WhiA protein family can be found in most Gram-positive bacteria, including the genetically simple cell wall-lacking mycoplasmas, and these proteins play a role in cell division. WhiA has some homology with eukaryotic homing endonucleases but lacks nuclease activity. Because of its DNA binding activity, it is assumed that the protein functions as a transcription factor, but this is not the case in the model system B. subtilis The function of this protein in B. subtilis remains unclear. We noticed that a whiA mutant has a mild chromosome segregation defect. Further studies of this phenomenon provided new support for a functional role of WhiA in cell division and indicated that the protein is required for normal chromosome segregation.
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11
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Abstract
SIGNIFICANCE Iron-sulfur cluster proteins carry out a wide range of functions, including as regulators of gene transcription/translation in response to environmental stimuli. In all known cases, the cluster acts as the sensory module, where the inherent reactivity/fragility of iron-sulfur clusters towards small/redox active molecules is exploited to effect conformational changes that modulate binding to DNA regulatory sequences. This promotes an often substantial re-programming of the cellular proteome that enables the organism or cell to adapt to, or counteract, its changing circumstances. Recent Advances. Significant progress has been made recently in the structural and mechanistic characterization of iron-sulfur cluster regulators and, in particular, the O2 and NO sensor FNR, the NO sensor NsrR, and WhiB-like proteins of Actinobacteria. These are the main focus of this review. CRITICAL ISSUES Striking examples of how the local environment controls the cluster sensitivity and reactivity are now emerging, but the basis for this is not yet fully understood for any regulatory family. FUTURE DIRECTIONS Characterization of iron-sulfur cluster regulators has long been hampered by a lack of high resolution structural data. Though this still presents a major future challenge, recent advances now provide a firm foundation for detailed understanding of how a signal is transduced to effect gene regulation. This requires the identification of often unstable intermediate species, which are difficult to detect and may be hard to distinguish using traditional techniques. Novel approaches will be required to solve these problems.
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Affiliation(s)
- Jason C Crack
- School of Chemistry , University of East Anglia , Norwich, United Kingdom of Great Britain and Northern Ireland , NR4 7TJ ;
| | - Nick E Le Brun
- University of East Anglia, School of Chemistry , University plain , Norwich, United Kingdom of Great Britain and Northern Ireland , NR4 7TJ ;
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12
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Lee DS, Kim P, Kim ES, Kim Y, Lee HS. Corynebacterium glutamicum WhcD interacts with WhiA to exert a regulatory effect on cell division genes. Antonie van Leeuwenhoek 2017; 111:641-648. [DOI: 10.1007/s10482-017-0953-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 09/30/2017] [Indexed: 11/30/2022]
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Flärdh K, McCormick JR. The Streptomyces O-B one connection: a force within layered repression of a key developmental decision. Mol Microbiol 2017; 104:695-699. [PMID: 28387974 DOI: 10.1111/mmi.13688] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2017] [Indexed: 11/30/2022]
Abstract
The study of Streptomyces development has made significant advances in the past few years and ongoing work is poised to add even more. One key to advancing the field has been the application of genome-wide approaches using Streptomyces venezuelae, which is capable of fairly synchronous sporulation in submerged growth conditions. WhiA and WhiB are well-known transcriptional regulators governing the pathway for spore formation in aerial hyphae. Recent ChIP-seq and RNA expression analyses indicated that WhiA and WhiB regulate the same set of genes, each being dependent on the presence of the other to exert control. Functional WhiAB is believed to form when developmental accumulation of WhiB joins constitutive accumulation of WhiA, suggesting that an important developmental decision is the control of WhiB accumulation. Now, a new WhiAB-controlled gene called bldO has been described and characterized. Strikingly, BldO has one target for repression in the entire genome, whiB. BldO now joins pleiotropic repressor BldD to exert a multi-layer control of the temporal and spatial activity of WhiB. BldD activity is controlled by c-di-GMP concentration and BldO potentially responds to an unknown signal. Together BldO and BldD repress developmental genes from being expressed until the appropriate time.
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Affiliation(s)
- Klas Flärdh
- Department of Biology, Lund University, Lund, 223 62, Sweden
| | - Joseph R McCormick
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA, 15282, USA
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Genome-Wide Chromatin Immunoprecipitation Sequencing Analysis Shows that WhiB Is a Transcription Factor That Cocontrols Its Regulon with WhiA To Initiate Developmental Cell Division in Streptomyces. mBio 2016; 7:e00523-16. [PMID: 27094333 PMCID: PMC4850268 DOI: 10.1128/mbio.00523-16] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
WhiB is the founding member of a family of proteins (the WhiB-like [Wbl] family) that carry a [4Fe-4S] iron-sulfur cluster and play key roles in diverse aspects of the biology of actinomycetes, including pathogenesis, antibiotic resistance, and the control of development. In Streptomyces, WhiB is essential for the process of developmentally controlled cell division that leads to sporulation. The biochemical function of Wbl proteins has been controversial; here, we set out to determine unambiguously if WhiB functions as a transcription factor using chromatin immunoprecipitation sequencing (ChIP-seq) in Streptomyces venezuelae. In the first demonstration of in vivo genome-wide Wbl binding, we showed that WhiB regulates the expression of key genes required for sporulation by binding upstream of ~240 transcription units. Strikingly, the WhiB regulon is identical to the previously characterized WhiA regulon, providing an explanation for the identical phenotypes of whiA and whiB mutants. Using ChIP-seq, we demonstrated that in vivo DNA binding by WhiA depends on WhiB and vice versa, showing that WhiA and WhiB function cooperatively to control expression of a common set of WhiAB target genes. Finally, we show that mutation of the cysteine residues that coordinate the [4Fe-4S] cluster in WhiB prevents DNA binding by both WhiB and WhiA in vivo. Despite the central importance of WhiB-like (Wbl) proteins in actinomycete biology, a conclusive demonstration of their biochemical function has been elusive, and they have been difficult to study, particularly in vitro, largely because they carry an oxygen-sensitive [4Fe-4S] cluster. Here we used genome-wide ChIP-seq to investigate the function of Streptomyces WhiB, the founding member of the Wbl family. The advantage of this approach is that the oxygen sensitivity of the [4Fe-4S] cluster becomes irrelevant once the protein has been cross-linked to DNA in vivo. Our data provide the most compelling in vivo evidence to date that WhiB, and, by extension, probably all Wbl proteins, function as transcription factors. Further, we show that WhiB does not act independently but rather coregulates its regulon of sporulation genes with a partner transcription factor, WhiA.
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c-di-GMP signalling and the regulation of developmental transitions in streptomycetes. Nat Rev Microbiol 2015; 13:749-60. [PMID: 26499894 DOI: 10.1038/nrmicro3546] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The complex life cycle of streptomycetes involves two distinct filamentous cell forms: the growing (or vegetative) hyphae and the reproductive (or aerial) hyphae, which differentiate into long chains of spores. Until recently, little was known about the signalling pathways that regulate the developmental transitions leading to sporulation. In this Review, we discuss important new insights into these pathways that have led to the emergence of a coherent regulatory network, focusing on the erection of aerial hyphae and the synchronous cell division event that produces dozens of unigenomic spores. In particular, we highlight the role of cyclic di-GMP (c-di-GMP) in controlling the initiation of development, and the role of the master regulator BldD in mediating c-di-GMP signalling.
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16
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Han Q, Zhou C, Wu S, Liu Y, Triplett L, Miao J, Tokuhisa J, Deblais L, Robinson H, Leach JE, Li J, Zhao B. Crystal Structure of Xanthomonas AvrRxo1-ORF1, a Type III Effector with a Polynucleotide Kinase Domain, and Its Interactor AvrRxo1-ORF2. Structure 2015; 23:1900-1909. [PMID: 26344722 DOI: 10.1016/j.str.2015.06.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 05/19/2015] [Accepted: 06/30/2015] [Indexed: 12/27/2022]
Abstract
Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak (BLS) disease on rice plants. Xoc delivers a type III effector AvrRxo1-ORF1 into rice plant cells that can be recognized by disease resistance (R) protein Rxo1, and triggers resistance to BLS disease. However, the mechanism and virulence role of AvrRxo1 is not known. In the genome of Xoc, AvrRxo1-ORF1 is adjacent to another gene AvrRxo1-ORF2, which was predicted to encode a molecular chaperone of AvrRxo1-ORF1. We report the co-purification and crystallization of the AvrRxo1-ORF1:AvrRxo1-ORF2 tetramer complex at 1.64 Å resolution. AvrRxo1-ORF1 has a T4 polynucleotide kinase domain, and expression of AvrRxo1-ORF1 suppresses bacterial growth in a manner dependent on the kinase motif. Although AvrRxo1-ORF2 binds AvrRxo1-ORF1, it is structurally different from typical effector-binding chaperones, in that it has a distinct fold containing a novel kinase-binding domain. AvrRxo1-ORF2 functions to suppress the bacteriostatic activity of AvrRxo1-ORF1 in bacterial cells.
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Affiliation(s)
- Qian Han
- Laboratory of Tropical Veterinary Medicine and Vector Biology, and Hainan Key Laboratory of Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University, Haikou 570228, Hainan, China; Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Changhe Zhou
- Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA
| | - Shuchi Wu
- Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA
| | - Yi Liu
- Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA
| | - Lindsay Triplett
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO 80523-1177, USA
| | - Jiamin Miao
- Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA
| | - James Tokuhisa
- Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA
| | - Loïc Deblais
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO 80523-1177, USA
| | - Howard Robinson
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Jan E Leach
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO 80523-1177, USA
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Bingyu Zhao
- Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA.
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Lluch-Senar M, Delgado J, Chen WH, Lloréns-Rico V, O'Reilly FJ, Wodke JA, Unal EB, Yus E, Martínez S, Nichols RJ, Ferrar T, Vivancos A, Schmeisky A, Stülke J, van Noort V, Gavin AC, Bork P, Serrano L. Defining a minimal cell: essentiality of small ORFs and ncRNAs in a genome-reduced bacterium. Mol Syst Biol 2015; 11:780. [PMID: 25609650 PMCID: PMC4332154 DOI: 10.15252/msb.20145558] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Identifying all essential genomic components is critical for the assembly of minimal artificial life. In the genome-reduced bacterium Mycoplasma pneumoniae, we found that small ORFs (smORFs; < 100 residues), accounting for 10% of all ORFs, are the most frequently essential genomic components (53%), followed by conventional ORFs (49%). Essentiality of smORFs may be explained by their function as members of protein and/or DNA/RNA complexes. In larger proteins, essentiality applied to individual domains and not entire proteins, a notion we could confirm by expression of truncated domains. The fraction of essential non-coding RNAs (ncRNAs) non-overlapping with essential genes is 5% higher than of non-transcribed regions (0.9%), pointing to the important functions of the former. We found that the minimal essential genome is comprised of 33% (269,410 bp) of the M. pneumoniae genome. Our data highlight an unexpected hidden layer of smORFs with essential functions, as well as non-coding regions, thus changing the focus when aiming to define the minimal essential genome.
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Affiliation(s)
- Maria Lluch-Senar
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Javier Delgado
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Wei-Hua Chen
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Verónica Lloréns-Rico
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | | | - Judith Ah Wodke
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain Theoretical Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - E Besray Unal
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Eva Yus
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Sira Martínez
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | | | - Tony Ferrar
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Ana Vivancos
- Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Arne Schmeisky
- Department of General Microbiology, Institute for Microbiology and Genetics, Göttingen, Germany
| | - Jörg Stülke
- Department of General Microbiology, Institute for Microbiology and Genetics, Göttingen, Germany
| | - Vera van Noort
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
| | | | - Peer Bork
- European Molecular Biology Laboratory, Heidelberg, Germany Max-Delbrück-Centre (MDC) for Molecular Medicine, Berlin, Germany
| | - Luis Serrano
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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18
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Chandra G, Chater KF. Developmental biology of Streptomyces from the perspective of 100 actinobacterial genome sequences. FEMS Microbiol Rev 2014; 38:345-79. [PMID: 24164321 PMCID: PMC4255298 DOI: 10.1111/1574-6976.12047] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 08/06/2013] [Accepted: 08/20/2013] [Indexed: 12/22/2022] Open
Abstract
To illuminate the evolution and mechanisms of actinobacterial complexity, we evaluate the distribution and origins of known Streptomyces developmental genes and the developmental significance of actinobacteria-specific genes. As an aid, we developed the Actinoblast database of reciprocal blastp best hits between the Streptomyces coelicolor genome and more than 100 other actinobacterial genomes (http://streptomyces.org.uk/actinoblast/). We suggest that the emergence of morphological complexity was underpinned by special features of early actinobacteria, such as polar growth and the coupled participation of regulatory Wbl proteins and the redox-protecting thiol mycothiol in transducing a transient nitric oxide signal generated during physiologically stressful growth transitions. It seems that some cell growth and division proteins of early actinobacteria have acquired greater importance for sporulation of complex actinobacteria than for mycelial growth, in which septa are infrequent and not associated with complete cell separation. The acquisition of extracellular proteins with structural roles, a highly regulated extracellular protease cascade, and additional regulatory genes allowed early actinobacterial stationary phase processes to be redeployed in the emergence of aerial hyphae from mycelial mats and in the formation of spore chains. These extracellular proteins may have contributed to speciation. Simpler members of morphologically diverse clades have lost some developmental genes.
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19
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Hausner G, Hafez M, Edgell DR. Bacterial group I introns: mobile RNA catalysts. Mob DNA 2014; 5:8. [PMID: 24612670 PMCID: PMC3984707 DOI: 10.1186/1759-8753-5-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 02/24/2014] [Indexed: 12/02/2022] Open
Abstract
Group I introns are intervening sequences that have invaded tRNA, rRNA and protein coding genes in bacteria and their phages. The ability of group I introns to self-splice from their host transcripts, by acting as ribozymes, potentially renders their insertion into genes phenotypically neutral. Some group I introns are mobile genetic elements due to encoded homing endonuclease genes that function in DNA-based mobility pathways to promote spread to intronless alleles. Group I introns have a limited distribution among bacteria and the current assumption is that they are benign selfish elements, although some introns and homing endonucleases are a source of genetic novelty as they have been co-opted by host genomes to provide regulatory functions. Questions regarding the origin and maintenance of group I introns among the bacteria and phages are also addressed.
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Affiliation(s)
- Georg Hausner
- Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2 N2, Canada
| | - Mohamed Hafez
- Department of Biochemistry, Faculty of Medicine, University of Montreal, Montréal, QC H3C 3 J7, Canada
- Department of Botany, Faculty of Science, Suez University, Suez, Egypt
| | - David R Edgell
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
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Abstract
Homing endonucleases are strong drivers of genetic exchange and horizontal transfer of both their own genes and their local genetic environment. The mechanisms that govern the function and evolution of these genetic oddities have been well documented over the past few decades at the genetic, biochemical, and structural levels. This wealth of information has led to the manipulation and reprogramming of the endonucleases and to their exploitation in genome editing for use as therapeutic agents, for insect vector control and in agriculture. In this chapter we summarize the molecular properties of homing endonucleases and discuss their strengths and weaknesses in genome editing as compared to other site-specific nucleases such as zinc finger endonucleases, TALEN, and CRISPR-derived endonucleases.
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Salerno P, Persson J, Bucca G, Laing E, Ausmees N, Smith CP, Flärdh K. Identification of new developmentally regulated genes involved in Streptomyces coelicolor sporulation. BMC Microbiol 2013; 13:281. [PMID: 24308424 PMCID: PMC3878966 DOI: 10.1186/1471-2180-13-281] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 11/26/2013] [Indexed: 11/10/2022] Open
Abstract
Background The sporulation of aerial hyphae of Streptomyces coelicolor is a complex developmental process. Only a limited number of the genes involved in this intriguing morphological differentiation programme are known, including some key regulatory genes. The aim of this study was to expand our knowledge of the gene repertoire involved in S. coelicolor sporulation. Results We report a DNA microarray-based investigation of developmentally controlled gene expression in S. coelicolor. By comparing global transcription patterns of the wild-type parent and two mutants lacking key regulators of aerial hyphal sporulation, we found a total of 114 genes that had significantly different expression in at least one of the two mutants compared to the wild-type during sporulation. A whiA mutant showed the largest effects on gene expression, while only a few genes were specifically affected by whiH mutation. Seven new sporulation loci were investigated in more detail with respect to expression patterns and mutant phenotypes. These included SCO7449-7451 that affect spore pigment biogenesis; SCO1773-1774 that encode an L-alanine dehydrogenase and a regulator-like protein and are required for maturation of spores; SCO3857 that encodes a protein highly similar to a nosiheptide resistance regulator and affects spore maturation; and four additional loci (SCO4421, SCO4157, SCO0934, SCO1195) that show developmental regulation but no overt mutant phenotype. Furthermore, we describe a new promoter-probe vector that takes advantage of the red fluorescent protein mCherry as a reporter of cell type-specific promoter activity. Conclusion Aerial hyphal sporulation in S. coelicolor is a technically challenging process for global transcriptomic investigations since it occurs only as a small fraction of the colony biomass and is not highly synchronized. Here we show that by comparing a wild-type to mutants lacking regulators that are specifically affecting processes in aerial hypha, it is possible to identify previously unknown genes with important roles in sporulation. The transcriptomic data reported here should also serve as a basis for identification of further developmentally important genes in future functional studies.
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Affiliation(s)
| | | | | | | | | | | | - Klas Flärdh
- Department of Biology, Lund University, Sölvegatan 35, 22362 Lund, Sweden.
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22
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The conserved DNA-binding protein WhiA is involved in cell division in Bacillus subtilis. J Bacteriol 2013; 195:5450-60. [PMID: 24097947 DOI: 10.1128/jb.00507-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial cell division is a highly coordinated process that begins with the polymerization of the tubulin-like protein FtsZ at midcell. FtsZ polymerization is regulated by a set of conserved cell division proteins, including ZapA. However, a zapA mutation does not result in a clear phenotype in Bacillus subtilis. In this study, we used a synthetic-lethal screen to find genes that become essential when ZapA is mutated. Three transposon insertions were found in yvcL. The deletion of yvcL in a wild-type background had only a mild effect on growth, but a yvcL zapA double mutant is very filamentous and sick. This filamentation is caused by a strong reduction in FtsZ-ring assembly, suggesting that YvcL is involved in an early stage of cell division. YvcL is 25% identical and 50% similar to the Streptomyces coelicolor transcription factor WhiA, which induces ftsZ and is required for septation of aerial hyphae during sporulation. Using green fluorescent protein fusions, we show that YvcL localizes at the nucleoid. Surprisingly, transcriptome analyses in combination with a ChIP-on-chip assay gave no indication that YvcL functions as a transcription factor. To gain more insight into the function of YvcL, we searched for suppressors of the filamentous phenotype of a yvcL zapA double mutant. Transposon insertions in gtaB and pgcA restored normal cell division of the double mutant. The corresponding proteins have been implicated in the metabolic sensing of cell division. We conclude that YvcL (WhiA) is involved in cell division in B. subtilis through an as-yet-unknown mechanism.
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Bush MJ, Bibb MJ, Chandra G, Findlay KC, Buttner MJ. Genes required for aerial growth, cell division, and chromosome segregation are targets of WhiA before sporulation in Streptomyces venezuelae. mBio 2013; 4:e00684-13. [PMID: 24065632 PMCID: PMC3781837 DOI: 10.1128/mbio.00684-13] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 08/23/2013] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED WhiA is a highly unusual transcriptional regulator related to a family of eukaryotic homing endonucleases. WhiA is required for sporulation in the filamentous bacterium Streptomyces, but WhiA homologues of unknown function are also found throughout the Gram-positive bacteria. To better understand the role of WhiA in Streptomyces development and its function as a transcription factor, we identified the WhiA regulon through a combination of chromatin immunoprecipitation-sequencing (ChIP-seq) and microarray transcriptional profiling, exploiting a new model organism for the genus, Streptomyces venezuelae, which sporulates in liquid culture. The regulon encompasses ~240 transcription units, and WhiA appears to function almost equally as an activator and as a repressor. Bioinformatic analysis of the upstream regions of the complete regulon, combined with DNase I footprinting, identified a short but highly conserved asymmetric sequence, GACAC, associated with the majority of WhiA targets. Construction of a null mutant showed that whiA is required for the initiation of sporulation septation and chromosome segregation in S. venezuelae, and several genes encoding key proteins of the Streptomyces cell division machinery, such as ftsZ, ftsW, and ftsK, were found to be directly activated by WhiA during development. Several other genes encoding proteins with important roles in development were also identified as WhiA targets, including the sporulation-specific sigma factor σ(WhiG) and the diguanylate cyclase CdgB. Cell division is tightly coordinated with the orderly arrest of apical growth in the sporogenic cell, and filP, encoding a key component of the polarisome that directs apical growth, is a direct target for WhiA-mediated repression during sporulation. IMPORTANCE Since the initial identification of the genetic loci required for Streptomyces development, all of the bld and whi developmental master regulators have been cloned and characterized, and significant progress has been made toward understanding the cell biological processes that drive morphogenesis. A major challenge now is to connect the cell biological processes and the developmental master regulators by dissecting the regulatory networks that link the two. Studies of these regulatory networks have been greatly facilitated by the recent introduction of Streptomyces venezuelae as a new model system for the genus, a species that sporulates in liquid culture. Taking advantage of S. venezuelae, we have characterized the regulon of genes directly under the control of one of these master regulators, WhiA. Our results implicate WhiA in the direct regulation of key steps in sporulation, including the cessation of aerial growth, the initiation of cell division, and chromosome segregation.
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Affiliation(s)
- Matthew J Bush
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom.
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Barzantny H, Schröder J, Strotmeier J, Fredrich E, Brune I, Tauch A. The transcriptional regulatory network of Corynebacterium jeikeium K411 and its interaction with metabolic routes contributing to human body odor formation. J Biotechnol 2012; 159:235-48. [DOI: 10.1016/j.jbiotec.2012.01.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 01/12/2012] [Accepted: 01/17/2012] [Indexed: 01/08/2023]
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25
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Taylor GK, Stoddard BL. Structural, functional and evolutionary relationships between homing endonucleases and proteins from their host organisms. Nucleic Acids Res 2012; 40:5189-200. [PMID: 22406833 PMCID: PMC3384342 DOI: 10.1093/nar/gks226] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Homing endonucleases (HEs) are highly specific DNA-cleaving enzymes that are encoded by invasive DNA elements (usually mobile introns or inteins) within the genomes of phage, bacteria, archea, protista and eukaryotic organelles. Six unique structural HE families, that collectively span four distinct nuclease catalytic motifs, have been characterized to date. Members of each family display structural homology and functional relationships to a wide variety of proteins from various organisms. The biological functions of those proteins are highly disparate and include non-specific DNA-degradation enzymes, restriction endonucleases, DNA-repair enzymes, resolvases, intron splicing factors and transcription factors. These relationships suggest that modern day HEs share common ancestors with proteins involved in genome fidelity, maintenance and gene expression. This review summarizes the results of structural studies of HEs and corresponding proteins from host organisms that have illustrated the manner in which these factors are related.
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Affiliation(s)
- Gregory K Taylor
- Graduate Program in Molecular and Cellular Biology, University of Washington and Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. A3-025, Seattle, WA 90109, USA
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26
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McCormick JR, Flärdh K. Signals and regulators that govern Streptomyces development. FEMS Microbiol Rev 2012; 36:206-31. [PMID: 22092088 PMCID: PMC3285474 DOI: 10.1111/j.1574-6976.2011.00317.x] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 10/29/2011] [Accepted: 10/30/2011] [Indexed: 12/16/2022] Open
Abstract
Streptomyces coelicolor is the genetically best characterized species of a populous genus belonging to the gram-positive Actinobacteria. Streptomycetes are filamentous soil organisms, well known for the production of a plethora of biologically active secondary metabolic compounds. The Streptomyces developmental life cycle is uniquely complex and involves coordinated multicellular development with both physiological and morphological differentiation of several cell types, culminating in the production of secondary metabolites and dispersal of mature spores. This review presents a current appreciation of the signaling mechanisms used to orchestrate the decision to undergo morphological differentiation, and the regulators and regulatory networks that direct the intriguing development of multigenomic hyphae first to form specialized aerial hyphae and then to convert them into chains of dormant spores. This current view of S. coelicolor development is destined for rapid evolution as data from '-omics' studies shed light on gene regulatory networks, new genetic screens identify hitherto unknown players, and the resolution of our insights into the underlying cell biological processes steadily improve.
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Affiliation(s)
| | - Klas Flärdh
- Department of Biology, Lund University, Lund, Sweden
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27
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DNA recognition and transcriptional regulation by the WhiA sporulation factor. Sci Rep 2011; 1:156. [PMID: 22355671 PMCID: PMC3240954 DOI: 10.1038/srep00156] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 10/27/2011] [Indexed: 01/23/2023] Open
Abstract
Sporulation in the filamentous bacteria Streptomyces coelicolor is a tightly regulated process involving aerial hyphae growth, chromosome segregation, septation and spore maturation. Genetic studies have identified numerous genes that regulate sporulation, including WhiA and the sigma factor WhiG. WhiA, which has been postulated to be a transcriptional regulator, contains two regions typically associated with DNA binding: an N-terminal domain similar to LAGLIDADG homing endonucleases, and a C-terminal helix-turn-helix domain. We characterized several in vitro activities displayed by WhiA. It binds at least two sporulation-specific promoters: its own and that of parABp2. DNA binding is primarily driven by its HTH domain, but requires full-length protein for maximum affinity. WhiA transcription is stimulated by WhiG, while the WhiA protein binds directly to WhiG (leading to inhibition of WhiG-dependent transcription). These separate activities, which resemble a possible feedback loop, may help coordinate the closely timed cessation of aerial growth and subsequent spore formation.
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Towards artificial metallonucleases for gene therapy: recent advances and new perspectives. Future Med Chem 2011; 3:1935-66. [DOI: 10.4155/fmc.11.139] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The process of DNA targeting or repair of mutated genes within the cell, induced by specifically positioned double-strand cleavage of DNA near the mutated sequence, can be applied for gene therapy of monogenic diseases. For this purpose, highly specific artificial metallonucleases are developed. They are expected to be important future tools of modern genetics. The present state of art and strategies of research are summarized, including protein engineering and artificial ‘chemical’ nucleases. From the results, we learn about the basic role of the metal ions and the various ligands, and about the DNA binding and cleavage mechanism. The results collected provide useful guidance for engineering highly controlled enzymes for use in gene therapy.
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Stoddard BL. Homing endonucleases: from microbial genetic invaders to reagents for targeted DNA modification. Structure 2011; 19:7-15. [PMID: 21220111 DOI: 10.1016/j.str.2010.12.003] [Citation(s) in RCA: 214] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 12/14/2010] [Accepted: 12/15/2010] [Indexed: 12/23/2022]
Abstract
Homing endonucleases are microbial DNA-cleaving enzymes that mobilize their own reading frames by generating double strand breaks at specific genomic invasion sites. These proteins display an economy of size, and yet recognize long DNA sequences (typically 20 to 30 base pairs). They exhibit a wide range of fidelity at individual nucleotide positions in a manner that is strongly influenced by host constraints on the coding sequence of the targeted gene. The activity of these proteins leads to site-specific recombination events that can result in the insertion, deletion, mutation, or correction of DNA sequences. Over the past fifteen years, the crystal structures of representatives from several homing endonuclease families have been solved, and methods have been described to create variants of these enzymes that cleave novel DNA targets. Engineered homing endonucleases proteins are now being used to generate targeted genomic modifications for a variety of biotech and medical applications.
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Affiliation(s)
- Barry L Stoddard
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., A3-025, Seattle, WA 98109, USA.
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Evolution of I-SceI homing endonucleases with increased DNA recognition site specificity. J Mol Biol 2010; 405:185-200. [PMID: 21029741 DOI: 10.1016/j.jmb.2010.10.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 10/14/2010] [Accepted: 10/18/2010] [Indexed: 12/22/2022]
Abstract
Elucidating how homing endonucleases undergo changes in recognition site specificity will facilitate efforts to engineer proteins for gene therapy applications. I-SceI is a monomeric homing endonuclease that recognizes and cleaves within an 18-bp target. It tolerates limited degeneracy in its target sequence, including substitution of a C:G(+4) base pair for the wild-type A:T(+4) base pair. Libraries encoding randomized amino acids at I-SceI residue positions that contact or are proximal to A:T(+4) were used in conjunction with a bacterial one-hybrid system to select I-SceI derivatives that bind to recognition sites containing either the A:T(+4) or the C:G(+4) base pairs. As expected, isolates encoding wild-type residues at the randomized positions were selected using either target sequence. All I-SceI proteins isolated using the C:G(+4) recognition site included small side-chain substitutions at G100 and either contained (K86R/G100T, K86R/G100S and K86R/G100C) or lacked (G100A, G100T) a K86R substitution. Interestingly, the binding affinities of the selected variants for the wild-type A:T(+4) target are 4- to 11-fold lower than that of wild-type I-SceI, whereas those for the C:G(+4) target are similar. The increased specificity of the mutant proteins is also evident in binding experiments in vivo. These differences in binding affinities account for the observed ∼36-fold difference in target preference between the K86R/G100T and wild-type proteins in DNA cleavage assays. An X-ray crystal structure of the K86R/G100T mutant protein bound to a DNA duplex containing the C:G(+4) substitution suggests how sequence specificity of a homing enzyme can increase. This biochemical and structural analysis defines one pathway by which site specificity is augmented for a homing endonuclease.
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