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Cai H, Zhang H, Guo DH, Wang Y, Gu J. Genomic Data Mining Reveals Abundant Uncharacterized Transporters in Coccidioides immitis and Coccidioides posadasii. J Fungi (Basel) 2022; 8:jof8101064. [PMID: 36294626 PMCID: PMC9604845 DOI: 10.3390/jof8101064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/01/2022] [Accepted: 10/08/2022] [Indexed: 11/16/2022] Open
Abstract
Coccidioides immitis and Coccidioides posadasii are causative agents of coccidioidomycosis, commonly known as Valley Fever. The increasing Valley Fever cases in the past decades, the expansion of endemic regions, and the rising azole drug-resistant strains have underscored an urgent need for a better understanding of Coccidioides biology and new antifungal strategies. Transporters play essential roles in pathogen survival, growth, infection, and adaptation, and are considered as potential drug targets. However, the composition and roles of transport machinery in Coccidioides remain largely unknown. In this study, genomic data mining revealed an abundant, uncharacterized repertoire of transporters in Coccidioides genomes. The catalog included 1288 and 1235 transporter homologs in C. immitis and C. posadasii, respectively. They were further annotated to class, subclass, family, subfamily and range of substrates based on the Transport Classification (TC) system. They may play diverse roles in nutrient uptake, metabolite secretion, ion homeostasis, drug efflux, or signaling. This study represents an initial effort for a systems-level characterization of the transport machinery in these understudied fungal pathogens.
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Affiliation(s)
- Hong Cai
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA
- South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Hao Zhang
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA
- South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Daniel H. Guo
- Strake Jesuit College Preparatory, Houston, TX 77036, USA
| | - Yufeng Wang
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA
- South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, San Antonio, TX 78249, USA
- Correspondence: (Y.W.); (J.G.)
| | - Jianying Gu
- Department of Biology, College of Staten Island, City University of New York, Staten Island, New York, NY 10314, USA
- Correspondence: (Y.W.); (J.G.)
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Komachi K, Burgess SM. The Nup2 meiotic-autonomous region relieves inhibition of Nup60 to promote progression of meiosis and sporulation in Saccharomyces cerevisiae. Genetics 2022; 221:6550504. [PMID: 35302609 PMCID: PMC9071577 DOI: 10.1093/genetics/iyac045] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 03/10/2022] [Indexed: 11/22/2022] Open
Abstract
During meiosis, chromosomes undergo dramatic changes in structural organization, nuclear positioning, and motion. Although the nuclear pore complex has been shown to affect genome organization and function in vegetative cells, its role in meiotic chromosome dynamics has remained largely unexplored. Recent work in the budding yeast Saccharomyces cerevisiae demonstrated that the mobile nucleoporin Nup2 is required for normal progression through meiosis I prophase and sporulation in strains where telomere-led chromosome movement has been compromised. The meiotic-autonomous region, a short fragment of Nup2 responsible for its role in meiosis, was shown to localize to the nuclear envelope via Nup60 and to bind to meiotic chromosomes. To understand the relative contribution these 2 activities have on meiotic-autonomous region function, we first carried out a screen for meiotic-autonomous region mutants defective in sporulation and found that all the mutations disrupt interaction with both Nup60 and meiotic chromosomes. Moreover, nup60 mutants phenocopy nup2 mutants, exhibiting similar nuclear division kinetics, sporulation efficiencies, and genetic interactions with mutations that affect the telomere bouquet. Although full-length Nup60 requires Nup2 for function, removal of Nup60's C-terminus allows Nup60 to bind meiotic chromosomes and promotes sporulation without Nup2. In contrast, binding of the meiotic-autonomous region to meiotic chromosomes is completely dependent on Nup60. Our findings uncover an inhibitory function for the Nup60 C-terminus and suggest that Nup60 mediates recruitment of meiotic chromosomes to the nuclear envelope, while Nup2 plays a secondary role counteracting the inhibitory function in Nup60's C-terminus.
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Affiliation(s)
- Kelly Komachi
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Sean M Burgess
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA,Corresponding author: Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
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Chemudupati M, Johns M, Osmani SA. The mode of mitosis is dramatically modified by deletion of a single nuclear pore complex gene in Aspergillus nidulans. Fungal Genet Biol 2019; 130:72-81. [PMID: 31026588 DOI: 10.1016/j.fgb.2019.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 02/06/2023]
Abstract
Nuclear pore complex (NPC) proteins (Nups) play multiple roles during mitosis. In this study we expand these roles and reveal that in Aspergillus nidulans, compromising the core Nup84-120 subcomplex of the NPC modifies the mitotic behavior of the nuclear envelope (NE). In wildtype cells, the NE undergoes simultaneous double pinching events to separate daughter nuclei during mitotic exit, whereas in Nup84-120 complex mutants, only one restriction of the NE is observed. Investigating the basis for this modified behavior of the NE in Nup deleted cells uncovered previously unrealized roles for core Nups in mitotic exit. During wildtype anaphase, the NE surrounds the two separating daughter DNA masses which typically flank the central nucleolus, to form three distinct nuclear compartments. In contrast, deletion of core Nups frequently results in early nucleolar eviction from the mitotic nucleus, in turn causing an uncharacteristic dumbbell-shaped NE morphology of anaphase nuclei with a nuclear membrane bridge connecting the two forming G1 nuclei. Importantly, the absence of the nucleolus between the separating daughter nuclei during anaphase delays chromosome segregation and progression into G1 as nuclei remain connected by chromatin bridges. Proteins localizing to late segregating chromosome arms are observed between forming daughter nuclei, and the mitotic spindle fails to resolve in a timely manner. These chromatin bridges are occupied by the Aurora kinase until nuclei have fully separated, suggesting involvement of Aurora in monitoring mitotic spindle and nuclear membrane resolution during mitotic exit. Our findings thus reveal a novel requirement for core Nups in mediating nucleolar positioning during mitosis, which dictates the pattern of NE fissions during karyokinesis and facilitates normal chromosome segregation. The findings additionally demonstrate that the mode of mitosis can be dramatically modified by deletion of a single NPC gene and reveals surprising fluidity in mitotic mechanisms.
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Affiliation(s)
- Mahesh Chemudupati
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, United States; Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, United States
| | - Matthew Johns
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, United States
| | - Stephen A Osmani
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, United States; Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, United States.
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Pfeifer MA, Khang CH. A nuclear contortionist: the mitotic migration of Magnaporthe oryzae nuclei during plant infection. Mycology 2018; 9:202-210. [PMID: 30181926 PMCID: PMC6115875 DOI: 10.1080/21501203.2018.1482966] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 05/25/2018] [Indexed: 01/22/2023] Open
Abstract
Magnaporthe oryzae is a filamentous fungus, which causes significant destruction to cereal crops worldwide. To infect plant cells, the fungus develops specialised constricted structures such as the penetration peg and the invasive hyphal peg. Live-cell imaging of M. oryzae during plant infection reveals that nuclear migration occurs during intermediate mitosis, in which the nuclear envelope neither completely disassembles nor remains entirely intact. Remarkably, in M. oryzae, mitotic nuclei show incredible malleability while undergoing confined migration through the constricted penetration and invasive hyphal pegs. Here, we review early events in plant infection, discuss intermediate mitosis, and summarise current knowledge of intermediate mitotic nuclear migration in M. oryzae.
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Affiliation(s)
- Mariel A Pfeifer
- Department of Plant Biology, University of Georgia, Athens, GA30602, USA
| | - Chang Hyun Khang
- Department of Plant Biology, University of Georgia, Athens, GA30602, USA
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Zhou L, Obhof T, Schneider K, Feldbrügge M, Nienhaus GU, Kämper J. Cytoplasmic Transport Machinery of the SPF27 Homologue Num1 in Ustilago maydis. Sci Rep 2018; 8:3611. [PMID: 29483520 PMCID: PMC5832149 DOI: 10.1038/s41598-018-21628-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 02/07/2018] [Indexed: 01/15/2023] Open
Abstract
In the phytopathogenic basidiomycete Ustilago maydis, the Num1 protein has a pivotal function in hyphal morphogenesis. Num1 functions as a core component of the spliceosome-associated Prp19/CDC5 complex (NTC). The interaction of Num1 with the kinesin motor Kin1 suggests a connection between a component of the splicing machinery and cytoplasmic trafficking processes. Previously it was shown that Num1 localizes predominantly in the nucleus; however, due to the diffraction-limited spatial resolution of conventional optical microscopy, it was not possible to attribute the localization to specific structures within the cytoplasm. We have now employed super-resolution localization microscopy to visualize Num1 in the cytoplasm by fusing it to a tandem dimeric Eos fluorescent protein (tdEosFP). The Num1 protein is localized within the cytoplasm with an enhanced density in the vicinity of microtubules. Num1 movement is found predominantly close to the nucleus. Movement is dependent on its interaction partner Kin1, but independent of Kin3. Our results provide strong evidence that, in addition to its involvement in splicing in the nucleus, Num1 has an additional functional role in the cytosol connected to the Kin1 motor protein.
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Affiliation(s)
- Lu Zhou
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Theresa Obhof
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Karina Schneider
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Michael Feldbrügge
- Institute of Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine-University, Düsseldorf, Germany
| | - G Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. .,Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. .,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA. .,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany.
| | - Jörg Kämper
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
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6
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Nuclear pore complex tethers to the cytoskeleton. Semin Cell Dev Biol 2017; 68:52-58. [PMID: 28676424 DOI: 10.1016/j.semcdb.2017.06.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 06/23/2017] [Indexed: 12/21/2022]
Abstract
The nuclear envelope is tethered to the cytoskeleton. The best known attachments of all elements of the cytoskeleton are via the so-called LINC complex. However, the nuclear pore complexes, which mediate the transport of soluble and membrane bound molecules, are also linked to the microtubule network, primarily via motor proteins (dynein and kinesins) which are linked, most importantly, to the cytoplasmic filament protein of the nuclear pore complex, Nup358, by the adaptor BicD2. The evidence for such linkages and possible roles in nuclear migration, cell cycle control, nuclear transport and cell architecture are discussed.
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7
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Jiang C, Kaul N, Campbell J, Meyhofer E. A novel dual-color bifocal imaging system for single-molecule studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:053705. [PMID: 28571404 DOI: 10.1063/1.4983648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, we report the design and implementation of a dual-color bifocal imaging (DBI) system that is capable of acquiring two spectrally distinct, spatially registered images of objects located in either same or two distinct focal planes. We achieve this by separating an image into two channels with distinct chromatic properties and independently focusing both images onto a single CCD camera. The two channels in our device are registered with subpixel accuracy, and long-term stability of the registered images with nanometer-precision was accomplished by reducing the drift of the images to ∼5 nm. We demonstrate the capabilities of our DBI system by imaging biomolecules labeled with spectrally distinct dyes and micro- and nano-sized spheres located in different focal planes.
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Affiliation(s)
- Chang Jiang
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Neha Kaul
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jenna Campbell
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Edgar Meyhofer
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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8
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Co-delivery of cell-wall-forming enzymes in the same vesicle for coordinated fungal cell wall formation. Nat Microbiol 2016; 1:16149. [DOI: 10.1038/nmicrobiol.2016.149] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 07/21/2016] [Indexed: 11/09/2022]
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Martins TV, Evans MJ, Wysham DB, Morris RJ. Nuclear pores enable sustained perinuclear calcium oscillations. BMC SYSTEMS BIOLOGY 2016; 10:55. [PMID: 27449670 PMCID: PMC4957432 DOI: 10.1186/s12918-016-0289-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 06/14/2016] [Indexed: 11/16/2022]
Abstract
Background Calcium signalling relies on the flux of calcium ions across membranes yet how signals in different compartments are related remains unclear. In particular, similar calcium signals on both sides of the nuclear envelope have been reported and attributed to passive diffusion through nuclear pores. However, observed differing cytosolic and nucleosolic calcium signatures suggest that the signalling machinery in these compartments can act independently. Results We adapt the fire-diffuse-fire model to investigate the generation of perinuclear calcium oscillations. We demonstrate that autonomous spatio-temporal calcium patterns are still possible in the presence of nuclear and cytosolic coupling via nuclear pores. The presence or absence of this autonomy is dependent upon the strength of the coupling and the maximum firing rate of an individual calcium channel. In all cases, coupling through the nuclear pores enables robust signalling with respect to changes in the diffusion constant. Conclusions We show that contradictory interpretations of experimental data with respect to the autonomy of nuclear calcium oscillations can be reconciled within one model, with different observations being a consequence of varying nuclear pore permeabilities for calcium and refractory conditions of channels. Furthermore, our results provide an explanation for why calcium oscillations on both sides of the nuclear envelope may be beneficial for sustained perinuclear signaling. Electronic supplementary material The online version of this article (doi:10.1186/s12918-016-0289-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Teresa Vaz Martins
- Computational & Systems Biology and Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK.
| | - Matthew J Evans
- Computational & Systems Biology and Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK
| | - Derin B Wysham
- Mathematics Department, Wenatchee Valley College, Wenatchee, USA
| | - Richard J Morris
- Computational & Systems Biology and Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK
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10
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Kilaru S, Steinberg G. Yeast recombination-based cloning as an efficient way of constructing vectors for Zymoseptoria tritici. Fungal Genet Biol 2016; 79:76-83. [PMID: 26092792 PMCID: PMC4502459 DOI: 10.1016/j.fgb.2015.03.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/13/2015] [Accepted: 03/21/2015] [Indexed: 11/28/2022]
Abstract
Yeast recombination-based cloning (YRBC) is a reliable and inexpensive way of generating plasmids. We provide 4 vectors for YRBC that a cover different resistance genes. Using this technique promises rapid generation of molecular tools to study Z. tritici.
Many pathogenic fungi are genetically tractable. Analysis of their cellular organization and invasion mechanisms underpinning virulence determinants profits from exploiting such molecular tools as fluorescent fusion proteins or conditional mutant protein alleles. Generation of these tools requires efficient cloning methods, as vector construction is often a rate-limiting step. Here, we introduce an efficient yeast recombination-based cloning (YRBC) method to construct vectors for the fungus Zymoseptoria tritici. This method is of low cost and avoids dependency on the availability of restriction enzyme sites in the DNA sequence, as needed in more conventional restriction/ligation-based cloning procedures. Furthermore, YRBC avoids modification of the DNA of interest, indeed this potential risk limits the use of site-specific recombination systems, such as Gateway cloning. Instead, in YRBC, multiple DNA fragments, with 30 bp overlap sequences, are transformed into Saccharomyces cerevisiae, whereupon homologous recombination generates the vector in a single step. Here, we provide a detailed experimental protocol and four vectors, each encoding a different dominant selectable marker cassette, that enable YRBC of constructs to be used in the wheat pathogen Z. tritici.
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Affiliation(s)
- S Kilaru
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK.
| | - G Steinberg
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
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Asakawa H, Yang HJ, Hiraoka Y, Haraguchi T. Virtual Nuclear Envelope Breakdown and Its Regulators in Fission Yeast Meiosis. Front Cell Dev Biol 2016; 4:5. [PMID: 26870731 PMCID: PMC4735346 DOI: 10.3389/fcell.2016.00005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 01/15/2016] [Indexed: 11/24/2022] Open
Abstract
Ran, a small GTPase, is required for the spindle formation and nuclear envelope (NE) formation. After NE breakdown (NEBD) during mitosis in metazoan cells, the Ran-GTP gradient across the NE is lost and Ran-GTP becomes concentrated around chromatin, thus affecting the stability of microtubules and promoting the assembly of spindle microtubules and segregation of chromosomes. Mitosis in which chromosomes are segregated subsequent to NEBD is called “open mitosis.” In contrast, many fungi undergo a process termed “closed mitosis” in which chromosome segregation and spindle formation occur without NEBD. Although the fission yeast Schizosaccharomyces pombe undergoes a closed mitosis, it exhibits a short period during meiosis (anaphase of the second meiosis; called “anaphase II”) when nuclear and cytoplasmic proteins are mixed in the presence of intact NE and nuclear pore complexes (NPC). This “virtual” nuclear envelope breakdown (vNEBD) involves changes in the localization of RanGAP1, an activator of Ran-GTP hydrolysis. Recently, Nup132, a component of the structural core Nup107-160 subcomplex of the NPC, has been shown to be involved in the maintenance of the nuclear cytoplasmic barrier in yeast meiosis. In this review, we highlight the possible roles of RanGAP1 and Nup132 in vNEBD and discuss the biological significance of vNEBD in S. pombe meiosis.
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Affiliation(s)
- Haruhiko Asakawa
- Graduate School of Frontier Biosciences, Osaka University Suita, Japan
| | - Hui-Ju Yang
- Graduate School of Frontier Biosciences, Osaka University Suita, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan; Cell Biology Group, Advanced ICT Research Institute Kobe, National Institute of Information and Communications TechnologyKobe, Japan; Graduate School of Science, Department of Biology, Osaka UniversityToyonaka, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan; Cell Biology Group, Advanced ICT Research Institute Kobe, National Institute of Information and Communications TechnologyKobe, Japan; Graduate School of Science, Department of Biology, Osaka UniversityToyonaka, Japan
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12
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Spichal M, Brion A, Herbert S, Cournac A, Marbouty M, Zimmer C, Koszul R, Fabre E. Evidence for a dual role of actin in regulating chromosome organization and dynamics in yeast. J Cell Sci 2016; 129:681-92. [PMID: 26763908 DOI: 10.1242/jcs.175745] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 01/05/2016] [Indexed: 01/07/2023] Open
Abstract
Eukaryotic chromosomes undergo movements that are involved in the regulation of functional processes such as DNA repair. To better understand the origin of these movements, we used fluorescence microscopy, image analysis and chromosome conformation capture to quantify the actin contribution to chromosome movements and interactions in budding yeast. We show that both the cytoskeletal and nuclear actin drive local chromosome movements, independently of Csm4, a putative LINC protein. Inhibition of actin polymerization reduces subtelomere dynamics, resulting in more confined territories and enrichment in subtelomeric contacts. Artificial tethering of actin to nuclear pores increased both nuclear pore complex (NPC) and subtelomere motion. Chromosome loci that were positioned away from telomeres exhibited reduced motion in the presence of an actin polymerization inhibitor but were unaffected by the lack of Csm4. We further show that actin was required for locus mobility that was induced by targeting the chromatin-remodeling protein Ino80. Correlated with this, DNA repair by homologous recombination was less efficient. Overall, interphase chromosome dynamics are modulated by the additive effects of cytoskeletal actin through forces mediated by the nuclear envelope and nuclear actin, probably through the function of actin in chromatin-remodeling complexes.
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Affiliation(s)
- Maya Spichal
- INSERM UMR 944, Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, Hôpital St. Louis 1, Avenue Claude Vellefaux, Paris 75010, France CNRS, UMR 7212, Paris 75010, France Université Paris Diderot, Sorbonne Paris Cité, Paris 75010, France Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France Sorbonne Universités, UPMC Université Paris 6, Paris 75005, France
| | - Alice Brion
- INSERM UMR 944, Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, Hôpital St. Louis 1, Avenue Claude Vellefaux, Paris 75010, France CNRS, UMR 7212, Paris 75010, France Université Paris Diderot, Sorbonne Paris Cité, Paris 75010, France
| | - Sébastien Herbert
- Institut Pasteur, Unité Imagerie et Modélisation, Paris 75015, France CNRS, URA 2582, Paris 75015, France
| | - Axel Cournac
- Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
| | - Martial Marbouty
- Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
| | - Christophe Zimmer
- Institut Pasteur, Unité Imagerie et Modélisation, Paris 75015, France CNRS, URA 2582, Paris 75015, France
| | - Romain Koszul
- Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
| | - Emmanuelle Fabre
- INSERM UMR 944, Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, Hôpital St. Louis 1, Avenue Claude Vellefaux, Paris 75010, France CNRS, UMR 7212, Paris 75010, France Université Paris Diderot, Sorbonne Paris Cité, Paris 75010, France Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
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Tenorio-Gómez M, de Sena-Tomás C, Pérez-Martín J. MRN- and 9-1-1-Independent Activation of the ATR-Chk1 Pathway during the Induction of the Virulence Program in the Phytopathogen Ustilago maydis. PLoS One 2015; 10:e0137192. [PMID: 26367864 PMCID: PMC4573213 DOI: 10.1371/journal.pone.0137192] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 07/24/2015] [Indexed: 11/18/2022] Open
Abstract
DNA damage response (DDR) leads to DNA repair, and depending on the extent of the
damage, to further events, including cell death. Evidence suggests that cell
differentiation may also be a consequence of the DDR. During the formation of
the infective hypha in the phytopathogenic fungus Ustilago
maydis, two DDR kinases, Atr1 and Chk1, are required to induce a G2
cell cycle arrest, which in turn is essential to display the virulence program.
However, the triggering factor of DDR in this process has remained elusive. In
this report we provide data suggesting that no DNA damage is associated with the
activation of the DDR during the formation of the infective filament in
U. maydis. We have analyzed bulk DNA
replication during the formation of the infective filament, and we found no
signs of impaired DNA replication. Furthermore, using RPA-GFP fusion as a
surrogate marker of the presence of DNA damage, we were unable to detect any
sign of DNA damage at the cellular level. In addition, neither MRN nor 9-1-1
complexes, both instrumental to transmit the DNA damage signal, are required for
the induction of the above mentioned cell cycle arrest, as well as for
virulence. In contrast, we have found that the claspin-like protein Mrc1, which
in other systems serves as scaffold for Atr1 and Chk1, was required for both
processes. We discuss possible alternative ways to trigger the DDR, independent
of DNA damage, in U. maydis during virulence
program activation.
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Affiliation(s)
| | | | - Jose Pérez-Martín
- Instituto de Biología Funcional y Genómica
(CSIC), Salamanca, Spain
- * E-mail:
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14
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Maizels Y, Gerlitz G. Shaping of interphase chromosomes by the microtubule network. FEBS J 2015; 282:3500-24. [PMID: 26040675 DOI: 10.1111/febs.13334] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/11/2015] [Accepted: 06/01/2015] [Indexed: 12/31/2022]
Abstract
It is well established that microtubule dynamics play a major role in chromosome condensation and localization during mitosis. During interphase, however, it is assumed that the metazoan nuclear envelope presents a physical barrier, which inhibits interaction between the microtubules located in the cytoplasm and the chromatin fibers located in the nucleus. In recent years, it has become apparent that microtubule dynamics alter chromatin structure and function during interphase as well. Microtubule motor proteins transport several transcription factors and exogenous DNA (such as plasmid DNA) from the cytoplasm to the nucleus. Various soluble microtubule components are able to translocate into the nucleus, where they bind various chromatin elements leading to transcriptional alterations. In addition, microtubules may apply force on the nuclear envelope, which is transmitted into the nucleus, leading to changes in chromatin structure. Thus, microtubule dynamics during interphase may affect chromatin spatial organization, as well as transcription, replication and repair.
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Affiliation(s)
- Yael Maizels
- Department of Molecular Biology, Faculty of Natural Sciences, Ariel University, Israel
| | - Gabi Gerlitz
- Department of Molecular Biology, Faculty of Natural Sciences, Ariel University, Israel
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15
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Fluorescence-Based Methods for the Study of Protein Localization, Interaction, and Dynamics in Filamentous Fungi. Fungal Biol 2015. [DOI: 10.1007/978-3-319-22437-4_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Denoth-Lippuner A, Krzyzanowski MK, Stober C, Barral Y. Role of SAGA in the asymmetric segregation of DNA circles during yeast ageing. eLife 2014; 3. [PMID: 25402830 PMCID: PMC4232608 DOI: 10.7554/elife.03790] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 10/14/2014] [Indexed: 12/18/2022] Open
Abstract
In eukaryotes, intra-chromosomal recombination generates DNA circles, but little is known about how cells react to them. In yeast, partitioning of such circles to the mother cell at mitosis ensures their loss from the population but promotes replicative ageing. Nevertheless, the mechanisms of partitioning are debated. In this study, we show that the SAGA complex mediates the interaction of non-chromosomal DNA circles with nuclear pore complexes (NPCs) and thereby promotes their confinement in the mother cell. Reciprocally, this causes retention and accumulation of NPCs, which affects the organization of ageing nuclei. Thus, SAGA prevents the spreading of DNA circles by linking them to NPCs, but unavoidably causes accumulation of circles and NPCs in the mother cell, and thereby promotes ageing. Together, our data provide a unifying model for the asymmetric segregation of DNA circles and how age affects nuclear organization. DOI:http://dx.doi.org/10.7554/eLife.03790.001 Budding yeast is a microorganism that has been widely studied to understand how it and many other organisms, including animals, age over time. This yeast is so named because it proliferates by ‘budding’ daughter cells out of the surface of a mother cell. For each daughter cell that buds, the mother cell loses some fitness and eventually dies after a certain number of budding events. This process is called ‘replicative ageing’, and it also resembles the way that stem cells age. In contrast, the newly formed daughters essentially have their age ‘reset to zero’ and grow until they turn into mother cells themselves. Several molecules or factors have been linked to replicative ageing. These are retained in the mother cell during budding, rather than being passed on to the daughters. Non-chromosomal DNA circles, for example, are rings of DNA that detach from chromosomes during DNA repair and that accumulate inside the ageing mother cell over time. How the mother cells retain these circles of DNA is an on-going topic of debate. Similar to plants and animals, chromosomes in yeast cells are confined in a membrane-bound structure known as the cell nucleus. The nuclear membrane is perforated by channels called nuclear pore complexes that ensure the transport of molecules into, and out of, the nucleus. Now, Denoth-Lippuner et al. establish that for the non-chromosomal DNA circles to be efficiently confined in the mother cell, the DNA circles must be anchored to the nuclear pore complexes. Denoth-Lippuner et al. next asked how the DNA circles were anchored to these complexes; and found that another complex of proteins known as SAGA is involved. When components of the SAGA complex were deleted in budding yeast cells, non-chromosomal DNA circles spread into the daughters as well. On the other hand, artificially anchoring these DNA circles to the nuclear pore complex alleviated the need for the SAGA complex, in order to retain these molecules in the mother cell. Denoth-Lippuner et al. also show that SAGA-dependent attachment of the DNA circles to the nuclear pore complexes causes these complexes to remain in the mother cell. As a consequence, these nuclear pore complexes accumulate in the mother cells as they age. The number of nuclear pore complexes in the daughter cells, however, remained fairly constant. Together these data raise the question of whether the effects of DNA circles on the number and activity of the nuclear pores might account for their contribution to ageing, perhaps by affecting the workings of the nucleus. DOI:http://dx.doi.org/10.7554/eLife.03790.002
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Affiliation(s)
| | | | - Catherine Stober
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Yves Barral
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
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17
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Bielska E, Schuster M, Roger Y, Berepiki A, Soanes DM, Talbot NJ, Steinberg G. Hook is an adapter that coordinates kinesin-3 and dynein cargo attachment on early endosomes. ACTA ACUST UNITED AC 2014; 204:989-1007. [PMID: 24637326 PMCID: PMC3998801 DOI: 10.1083/jcb.201309022] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The Ustilago maydis Hook protein Hok1 is part of an evolutionarily conserved protein complex that regulates bidirectional early endosome trafficking by controlling attachment of both kinesin-3 and dynein. Bidirectional membrane trafficking along microtubules is mediated by kinesin-1, kinesin-3, and dynein. Several organelle-bound adapters for kinesin-1 and dynein have been reported that orchestrate their opposing activity. However, the coordination of kinesin-3/dynein-mediated transport is not understood. In this paper, we report that a Hook protein, Hok1, is essential for kinesin-3– and dynein-dependent early endosome (EE) motility in the fungus Ustilago maydis. Hok1 binds to EEs via its C-terminal region, where it forms a complex with homologues of human fused toes (FTS) and its interactor FTS- and Hook-interacting protein. A highly conserved N-terminal region is required to bind dynein and kinesin-3 to EEs. To change the direction of EE transport, kinesin-3 is released from organelles, and dynein binds subsequently. A chimaera of human Hook3 and Hok1 rescues the hok1 mutant phenotype, suggesting functional conservation between humans and fungi. We conclude that Hok1 is part of an evolutionarily conserved protein complex that regulates bidirectional EE trafficking by controlling attachment of both kinesin-3 and dynein.
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Affiliation(s)
- Ewa Bielska
- School of Biosciences, University of Exeter, Exeter EX4 4QD, England, UK
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18
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Higuchi Y, Ashwin P, Roger Y, Steinberg G. Early endosome motility spatially organizes polysome distribution. ACTA ACUST UNITED AC 2014; 204:343-57. [PMID: 24493587 PMCID: PMC3912533 DOI: 10.1083/jcb.201307164] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To distribute the protein translation machinery throughout the cytoplasm, polysomes in the fungus Ustilago maydis associate with mobile early endosomes, resulting in long-range motility along microtubules. Early endosomes (EEs) mediate protein sorting, and their cytoskeleton-dependent motility supports long-distance signaling in neurons. Here, we report an unexpected role of EE motility in distributing the translation machinery in a fungal model system. We visualize ribosomal subunit proteins and show that the large subunits diffused slowly throughout the cytoplasm (Dc,60S = 0.311 µm2/s), whereas entire polysomes underwent long-range motility along microtubules. This movement was mediated by “hitchhiking” on kinesin-3 and dynein-driven EEs, where the polysomes appeared to translate EE-associated mRNA into proteins. Modeling indicates that this motor-driven transport is required for even cellular distribution of newly formed ribosomes. Indeed, impaired EE motility in motor mutants, or their inability to bind EEs in mutants lacking the RNA-binding protein Rrm4, reduced ribosome transport and induced ribosome aggregation near the nucleus. As a consequence, cell growth was severely restricted. Collectively, our results indicate that polysomes associate with moving EEs and that “off- and reloading” distributes the protein translation machinery.
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Affiliation(s)
- Yujiro Higuchi
- Biosciences and 2 Mathematics Research Institute, University of Exeter, Exeter EX4 4QD, England, UK
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19
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Lusk CP, Colombi P. Toward a consensus on the mechanism of nuclear pore complex inheritance. Nucleus 2014; 5:97-102. [PMID: 24637838 DOI: 10.4161/nucl.28314] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Nuclear compartmentalization is achieved through the enclosure of the genome by the nuclear envelope; the nuclear envelope is perforated by nuclear pore complexes (NPCs), which form portals that control molecular exchange between the nucleus and cytoplasm. The number of NPCs per nucleus establishes a limit to the flux of molecules across the nuclear envelope and might directly impact genome organization and gene expression in a cell type specific manner. Mechanisms that control NPC number remain ill defined. Our recent study implicates a cytoplasmic pool of the nucleoporin Nsp1 as a factor that controls NPC number during the asymmetric division of budding yeast; Nsp1 acts to ensure that daughters inherit NPCs. We place our data within an emerging model of NPC inheritance in yeast and consider potential analogous mechanisms in multicellular eukaryotes, including the functional conservation of a cytoplasmic pool of Nsp1.
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20
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The SPF27 homologue Num1 connects splicing and kinesin 1-dependent cytoplasmic trafficking in Ustilago maydis. PLoS Genet 2014; 10:e1004046. [PMID: 24391515 PMCID: PMC3879195 DOI: 10.1371/journal.pgen.1004046] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 10/30/2013] [Indexed: 12/23/2022] Open
Abstract
The conserved NineTeen protein complex (NTC) is an integral subunit of the spliceosome and required for intron removal during pre-mRNA splicing. The complex associates with the spliceosome and participates in the regulation of conformational changes of core spliceosomal components, stabilizing RNA-RNA- as well as RNA-protein interactions. In addition, the NTC is involved in cell cycle checkpoint control, response to DNA damage, as well as formation and export of mRNP-particles. We have identified the Num1 protein as the homologue of SPF27, one of NTC core components, in the basidiomycetous fungus Ustilago maydis. Num1 is required for polarized growth of the fungal hyphae, and, in line with the described NTC functions, the num1 mutation affects the cell cycle and cell division. The num1 deletion influences splicing in U. maydis on a global scale, as RNA-Seq analysis revealed increased intron retention rates. Surprisingly, we identified in a screen for Num1 interacting proteins not only NTC core components as Prp19 and Cef1, but several proteins with putative functions during vesicle-mediated transport processes. Among others, Num1 interacts with the motor protein Kin1 in the cytoplasm. Similar phenotypes with respect to filamentous and polar growth, vacuolar morphology, as well as the motility of early endosomes corroborate the genetic interaction between Num1 and Kin1. Our data implicate a previously unidentified connection between a component of the splicing machinery and cytoplasmic transport processes. As the num1 deletion also affects cytoplasmic mRNA transport, the protein may constitute a novel functional interconnection between the two disparate processes of splicing and trafficking. In eukaryotic cells, nascent mRNA is processed by splicing to remove introns and to join the exon sequences. The processed mRNA is then transported out of the nucleus and employed by ribosomes to synthesize proteins. Splicing is achieved by the spliceosome and associated protein complexes, among them the so-called NineTeen complex (NTC). We have identified the Num1 protein as one of the core components of the NTC in the fungus Ustilago maydis, and could show that it is required for polarized growth of the filamentous fungal cells. Consistent with the NTC function, cells with a num1-deletion show reduced splicing of mRNA. Moreover, we uncover a novel cytoplasmic function of the Num1 protein: It physically interacts with the microtubule-associated Kinesin 1 motor protein, and phenotypic analyses corroborate that both proteins are functionally connected. Our findings reveal a yet unidentified role of a global splicing factor during intracellular trafficking processes. A possible connection between these disparate mechanisms presumably resides in mRNA-export out of the nucleus and/or the transport of mRNA within the cytoplasm.
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Makio T, Lapetina DL, Wozniak RW. Inheritance of yeast nuclear pore complexes requires the Nsp1p subcomplex. ACTA ACUST UNITED AC 2013; 203:187-96. [PMID: 24165935 PMCID: PMC3812975 DOI: 10.1083/jcb.201304047] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The presence of members of an NPC subcomplex containing Nsp1p is required for NPC movement into a daughter yeast cell, allowing intact NPCs to bypass a filter that prevents movement of defective complexes. In the yeast Saccharomyces cerevisiae, organelles and macromolecular complexes are delivered from the mother to the emerging daughter during cell division, thereby ensuring progeny viability. Here, we have shown that during mitosis nuclear pore complexes (NPCs) in the mother nucleus are actively delivered through the bud neck and into the daughter cell concomitantly with the nuclear envelope. Furthermore, we show that NPC movement into the daughter cell requires members of an NPC subcomplex containing Nsp1p and its interacting partners. NPCs lacking these nucleoporins (Nups) were blocked from entry into the daughter by a putative barrier at the bud neck. This selection process could be observed within individual cells such that NPCs containing Nup82p (an Nsp1p-interacting Nup) were transferred to the daughter cells while functionally compromised NPCs lacking Nup82p were retained in the mother. This mechanism is proposed to facilitate the inheritance of functional NPCs by daughter cells.
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Affiliation(s)
- Tadashi Makio
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
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22
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Colombi P, Webster BM, Fröhlich F, Lusk CP. The transmission of nuclear pore complexes to daughter cells requires a cytoplasmic pool of Nsp1. ACTA ACUST UNITED AC 2013; 203:215-32. [PMID: 24165936 PMCID: PMC3812967 DOI: 10.1083/jcb.201305115] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nuclear pore complexes (NPCs) are essential protein assemblies that span the nuclear envelope and establish nuclear-cytoplasmic compartmentalization. We have investigated mechanisms that control NPC number in mother and daughter cells during the asymmetric division of budding yeast. By simultaneously tracking existing NPCs and newly synthesized NPC protomers (nups) through anaphase, we uncovered a pool of the central channel nup Nsp1 that is actively targeted to the bud in association with endoplasmic reticulum. Bud targeting required an intact actin cytoskeleton and the class V myosin, Myo2. Selective inhibition of cytoplasmic Nsp1 or inactivation of Myo2 reduced the inheritance of NPCs in daughter cells, leading to a daughter-specific loss of viability. Our data are consistent with a model in which Nsp1 releases a barrier that otherwise prevents NPC passage through the bud neck. It further supports the finding that NPC inheritance, not de novo NPC assembly, is primarily responsible for controlling NPC number in daughter cells.
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Affiliation(s)
- Paolo Colombi
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
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23
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Walters AD, Cohen-Fix O. Nuclear division: giving daughters their fair share. Curr Biol 2013; 23:R1045-7. [PMID: 24309281 DOI: 10.1016/j.cub.2013.10.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
How do nuclear components, apart from chromosomes, partition equally to daughter nuclei during mitosis? In Schizosaccharomyces japonicus, the conserved LEM-domain nuclear envelope protein Man1 ensures the formation of identical daughter nuclei by coupling nuclear pore complexes to the segregating chromosomes.
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Affiliation(s)
- Alison D Walters
- The Laboratory of Cell and Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA.
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24
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Roberts AJ, Kon T, Knight PJ, Sutoh K, Burgess SA. Functions and mechanics of dynein motor proteins. Nat Rev Mol Cell Biol 2013; 14:713-26. [PMID: 24064538 DOI: 10.1038/nrm3667] [Citation(s) in RCA: 346] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Fuelled by ATP hydrolysis, dyneins generate force and movement on microtubules in a wealth of biological processes, including ciliary beating, cell division and intracellular transport. The large mass and complexity of dynein motors have made elucidating their mechanisms a sizable task. Yet, through a combination of approaches, including X-ray crystallography, cryo-electron microscopy, single-molecule assays and biochemical experiments, important progress has been made towards understanding how these giant motor proteins work. From these studies, a model for the mechanochemical cycle of dynein is emerging, in which nucleotide-driven flexing motions within the AAA+ ring of dynein alter the affinity of its microtubule-binding stalk and reshape its mechanical element to generate movement.
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Affiliation(s)
- Anthony J Roberts
- 1] Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK. [2] Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA
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25
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Dahan-Pasternak N, Nasereddin A, Kolevzon N, Pe'er M, Wong W, Shinder V, Turnbull L, Whitchurch CB, Elbaum M, Gilberger TW, Yavin E, Baum J, Dzikowski R. PfSec13 is an unusual chromatin-associated nucleoporin of Plasmodium falciparum that is essential for parasite proliferation in human erythrocytes. J Cell Sci 2013; 126:3055-69. [PMID: 23687383 DOI: 10.1242/jcs.122119] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Plasmodium falciparum, the deadliest form of human malaria, the nuclear periphery has drawn much attention due to its role as a sub-nuclear compartment involved in virulence gene expression. Recent data have implicated components of the nuclear envelope in regulating gene expression in several eukaryotes. Special attention has been given to nucleoporins that compose the nuclear pore complex (NPC). However, very little is known about components of the nuclear envelope in Plasmodium parasites. Here we characterize PfSec13, an unusual nucleoporin of P. falciparum, which shows unique structural similarities suggesting that it is a fusion between Sec13 and Nup145C of yeast. Using super resolution fluorescence microscopy (3D-SIM) and in vivo imaging, we show that the dynamic localization of PfSec13 during parasites' intra-erythrocytic development corresponds with that of the NPCs and that these dynamics are associated with microtubules rather than with F-actin. In addition, PfSec13 does not co-localize with the heterochormatin markers HP1 and H3K9me3, suggesting euchromatic location of the NPCs. The proteins associated with PfSec13 indicate that this unusual Nup is involved in several cellular processes. Indeed, ultrastructural and chromatin immunoprecipitation analyses revealed that, in addition to the NPCs, PfSec13 is found in the nucleoplasm where it is associated with chromatin. Finally, we used peptide nucleic acids (PNA) to downregulate PfSec13 and show that it is essential for parasite proliferation in human erythrocytes.
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Affiliation(s)
- Noa Dahan-Pasternak
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research Israel-Canada, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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26
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Abstract
In fungi, nuclear pore complexes are free to move through the nuclear envelope; however, little is known about how movement is regulated. New evidence reveals roles for molecular motors and potential impacts on genomic organization.
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Affiliation(s)
- Amanda K Casey
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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27
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Nuclear pores and perinuclear expression sites of var and ribosomal DNA genes correspond to physically distinct regions in Plasmodium falciparum. EUKARYOTIC CELL 2013; 12:697-702. [PMID: 23475702 DOI: 10.1128/ec.00023-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The human malaria parasite Plasmodium falciparum modifies the erythrocyte it infects by exporting variant proteins to the host cell surface. The var gene family that codes for a large, variant adhesive surface protein called P. falciparum erythrocyte membrane protein 1 (PfEMP1) plays a particular role in this process, which is linked to pathogenesis and immune evasion. A single member of this gene family is highly transcribed while the other 59 members remain silenced. Importantly, var gene transcription occurs at a spatially restricted, but yet undefined, perinuclear site that is distinct from repressed var gene clusters. To advance our understanding of monoallelic expression, we investigated whether nuclear pores associate with the var gene expression site. To this end, we studied the nuclear pore organization during the asexual blood stage using a specific antibody directed against a subunit of the nuclear pore, P. falciparum Nup116 (PfNup116). Ring and schizont stage parasites showed highly polarized nuclear pore foci, whereas in trophozoite stage nuclear pores redistributed over the entire nuclear surface. Colocalization studies of var transcripts and anti-PfNup116 antibodies showed clear dissociation between nuclear pores and the var gene expression site in ring stage. Similar results were obtained for another differentially transcribed perinuclear gene family, the ribosomal DNA units. Furthermore, we show that in the poised state, the var gene locus is not physically linked to nuclear pores. Our results indicate that P. falciparum does form compartments of high transcriptional activity at the nuclear periphery which are, unlike the case in yeast, devoid of nuclear pores.
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28
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Egan MJ, McClintock MA, Reck-Peterson SL. Microtubule-based transport in filamentous fungi. Curr Opin Microbiol 2012; 15:637-45. [PMID: 23127389 DOI: 10.1016/j.mib.2012.10.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/04/2012] [Accepted: 10/07/2012] [Indexed: 01/29/2023]
Abstract
Defects in microtubule-based transport are implicated in many neuropathologies. The filamentous fungi Aspergillus nidulans and Ustilago maydis are valuable models for studying transport owing to their yeast-like genetic and biochemical tractability and metazoan-like dependence on microtubule-based transport for cellular trafficking. In these organisms the role of microtubules in nuclear positioning is well studied, but recent work has expanded the range of cargos to include endosomes, messenger RNA, secretory vesicles, peroxisomes, and nuclear pore complexes, reflecting the diversity of metazoan systems. Furthermore, similarities in transport mechanisms exist between filamentous fungi and metazoan neurons, demonstrating the suitability of A. nidulans and U. maydis for studying the molecular basis of transport-related neuropathologies such as lissencephaly, motor neuron disease, and Perry syndrome.
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Affiliation(s)
- Martin J Egan
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States
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29
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Leslie M. Fungal pores feel the pull. J Biophys Biochem Cytol 2012. [PMCID: PMC3413359 DOI: 10.1083/jcb.1983iti1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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