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Gedman GL, Kimball TH, Atkinson LL, Factor D, Vojtova G, Farias-Virgens M, Wright TF, White SA. CHIRP-Seq: FoxP2 transcriptional targets in zebra finch brain include numerous speech and language-related genes. RESEARCH SQUARE 2024:rs.3.rs-4542378. [PMID: 38978588 PMCID: PMC11230500 DOI: 10.21203/rs.3.rs-4542378/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Background Vocal learning is a rare, convergent trait that is fundamental to both human speech and birdsong. The Forkhead Box P2 (FoxP2) transcription factor appears necessary for both types of learned signals, as human mutations in FoxP2 result in speech deficits, and disrupting its expression in zebra finches impairs male-specific song learning. In juvenile and adult male finches, striatal FoxP2 mRNA and protein decline acutely within song-dedicated neurons during singing, indicating that its transcriptional targets are also behaviorally regulated. The identities of these targets in songbirds, and whether they differ across sex, development and/or behavioral conditions, are largely unknown. Results Here we used chromatin immunoprecipitation followed by sequencing (ChIP-Seq) to identify genomic sites bound by FoxP2 in male and female, juvenile and adult, and singing and non-singing birds. Our results suggest robust FoxP2 binding concentrated in putative promoter regions of genes. The number of genes likely to be bound by FoxP2 varied across conditions, suggesting specialized roles of the candidate targets related to sex, age, and behavioral state. We validated these binding targets both bioinformatically, with comparisons to previous studies and biochemically, with immunohistochemistry using an antibody for a putative target gene. Gene ontology analyses revealed enrichment for human speech- and language-related functions in males only, consistent with the sexual dimorphism of song learning in this species. Fewer such targets were found in juveniles relative to adults, suggesting an expansion of this regulatory network with maturation. The fewest speech-related targets were found in the singing condition, consistent with the well-documented singing-driven down-regulation of FoxP2 in the songbird striatum. Conclusions Overall, these data provide an initial catalog of the regulatory landscape of FoxP2 in an avian vocal learner, offering dozens of target genes for future study and providing insight into the molecular underpinnings of vocal learning.
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2
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Kaposi's sarcoma-associated herpesvirus induces specialised ribosomes to efficiently translate viral lytic mRNAs. Nat Commun 2023; 14:300. [PMID: 36653366 PMCID: PMC9849454 DOI: 10.1038/s41467-023-35914-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 01/06/2023] [Indexed: 01/19/2023] Open
Abstract
Historically, ribosomes were viewed as unchanged homogeneous macromolecular machines with no regulatory capacity for mRNA translation. An emerging concept is that heterogeneity of ribosomal composition exists, exerting a regulatory function or specificity in translational control. This is supported by recent discoveries identifying compositionally distinct specialised ribosomes that actively regulate mRNA translation. Viruses lack their own translational machinery and impose high translational demands on the host during replication. We explore the possibility that KSHV manipulates ribosome biogenesis producing specialised ribosomes which preferentially translate viral transcripts. Quantitative proteomic analysis identified changes in the stoichiometry and composition of precursor ribosomal complexes during the switch from latent to lytic replication. We demonstrate the enhanced association of ribosomal biogenesis factors BUD23 and NOC4L, and the KSHV ORF11 protein, with small ribosomal subunit precursor complexes during lytic replication. BUD23 depletion resulted in significantly reduced viral gene expression, culminating in dramatic reduction of infectious virion production. Ribosome profiling demonstrated BUD23 is essential for reduced association of ribosomes with KSHV uORFs in late lytic genes, required for the efficient translation of the downstream coding sequence. Results provide mechanistic insights into KSHV-mediated manipulation of cellular ribosome composition inducing a population of specialised ribosomes facilitating efficient translation of viral mRNAs.
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3
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Pócsi I, Szigeti ZM, Emri T, Boczonádi I, Vereb G, Szöllősi J. Use of red, far-red, and near-infrared light in imaging of yeasts and filamentous fungi. Appl Microbiol Biotechnol 2022; 106:3895-3912. [PMID: 35599256 PMCID: PMC9200671 DOI: 10.1007/s00253-022-11967-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/02/2022] [Accepted: 05/07/2022] [Indexed: 11/30/2022]
Abstract
Abstract While phototoxicity can be a useful therapeutic modality not only for eliminating malignant cells but also in treating fungal infections, mycologists aiming to observe morphological changes or molecular events in fungi, especially when long observation periods or high light fluxes are warranted, encounter problems owed to altered regulatory pathways or even cell death caused by various photosensing mechanisms. Consequently, the ever expanding repertoire of visible fluorescent protein toolboxes and high-resolution microscopy methods designed to investigate fungi in vitro and in vivo need to comply with an additional requirement: to decrease the unwanted side effects of illumination. In addition to optimizing exposure, an obvious solution is red-shifted illumination, which, however, does not come without compromises. This review summarizes the interactions of fungi with light and the various molecular biology and technology approaches developed for exploring their functions on the molecular, cellular, and in vivo microscopic levels, and outlines the progress towards reducing phototoxicity through applying far-red and near-infrared light. Key points • Fungal biological processes alter upon illumination, also under the microscope • Red shifted fluorescent protein toolboxes decrease interference by illumination • Innovations like two-photon, lightsheet, and near IR microscopy reduce phototoxicity
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Affiliation(s)
- István Pócsi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.
| | - Zsuzsa M Szigeti
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - Tamás Emri
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - Imre Boczonádi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - György Vereb
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.,MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.,Faculty of Pharmacy, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - János Szöllősi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.,MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
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4
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Hopes T, Norris K, Agapiou M, McCarthy CGP, Lewis PA, O'Connell MJ, Fontana J, Aspden JL. Ribosome heterogeneity in Drosophila melanogaster gonads through paralog-switching. Nucleic Acids Res 2021; 50:2240-2257. [PMID: 34283226 PMCID: PMC8887423 DOI: 10.1093/nar/gkab606] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/23/2021] [Accepted: 07/02/2021] [Indexed: 12/02/2022] Open
Abstract
Ribosomes have long been thought of as homogeneous macromolecular machines, but recent evidence suggests they are heterogeneous and could be specialised to regulate translation. Here, we have characterised ribosomal protein heterogeneity across 4 tissues of Drosophila melanogaster. We find that testes and ovaries contain the most heterogeneous ribosome populations, which occurs through a combination of paralog-enrichment and paralog-switching. We have solved structures of ribosomes purified from in vivo tissues by cryo-EM, revealing differences in precise ribosomal arrangement for testis and ovary 80S ribosomes. Differences in the amino acid composition of paralog pairs and their localisation on the ribosome exterior indicate paralog-switching could alter the ribosome surface, enabling different proteins to regulate translation. One testis-specific paralog-switching pair is also found in humans, suggesting this is a conserved site of ribosome heterogeneity. Overall, this work allows us to propose that mRNA translation might be regulated in the gonads through ribosome heterogeneity, providing a potential means of ribosome specialisation.
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Affiliation(s)
- Tayah Hopes
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.,LeedsOmics, University of Leeds, Leeds, UK
| | - Karl Norris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.,LeedsOmics, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Michaela Agapiou
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.,LeedsOmics, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Charley G P McCarthy
- School of Life Sciences, Faculty of Medicine and Health Sciences, The University of Nottingham, Nottingham NG7 2RD, UK
| | - Philip A Lewis
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Mary J O'Connell
- School of Life Sciences, Faculty of Medicine and Health Sciences, The University of Nottingham, Nottingham NG7 2RD, UK
| | - Juan Fontana
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Julie L Aspden
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.,LeedsOmics, University of Leeds, Leeds, UK
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5
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Norris K, Hopes T, Aspden JL. Ribosome heterogeneity and specialization in development. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1644. [PMID: 33565275 PMCID: PMC8647923 DOI: 10.1002/wrna.1644] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 12/13/2022]
Abstract
Regulation of protein synthesis is a vital step in controlling gene expression, especially during development. Over the last 10 years, it has become clear that rather than being homogeneous machines responsible for mRNA translation, ribosomes are highly heterogeneous and can play an active part in translational regulation. These "specialized ribosomes" comprise of specific protein and/or rRNA components, which are required for the translation of particular mRNAs. However, while there is extensive evidence for ribosome heterogeneity, support for specialized functions is limited. Recent work in a variety of developmental model organisms has shed some light on the biological relevance of ribosome heterogeneity. Tissue-specific expression of ribosomal components along with phenotypic analysis of ribosomal gene mutations indicate that ribosome heterogeneity and potentially specialization are common in key development processes like embryogenesis, spermatogenesis, oogenesis, body patterning, and neurogenesis. Several examples of ribosome specialization have now been proposed but strong links between ribosome heterogeneity, translation of specific mRNAs by defined mechanisms, and role of these translation events remain elusive. Furthermore, several studies have indicated that heterogeneous ribosome populations are a product of tissue-specific expression rather than specialized function and that ribosomal protein phenotypes are the result of extra-ribosomal function or overall reduced ribosome levels. Many important questions still need to be addressed in order to determine the functional importance of ribosome heterogeneity to development and disease, which is likely to vary across systems. It will be essential to dissect these issues to fully understand diseases caused by disruptions to ribosomal composition, such as ribosomopathies. This article is categorized under: Translation > Translation Regulation Translation > Ribosome Structure/Function RNA in Disease and Development > RNA in Development.
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Affiliation(s)
- Karl Norris
- Faculty of Biological Sciences, School of Molecular and Cellular BiologyUniversity of LeedsLeedsUK
- Leeds OmicsUniversity of LeedsLeedsUK
| | - Tayah Hopes
- Faculty of Biological Sciences, School of Molecular and Cellular BiologyUniversity of LeedsLeedsUK
- Leeds OmicsUniversity of LeedsLeedsUK
| | - Julie Louise Aspden
- Faculty of Biological Sciences, School of Molecular and Cellular BiologyUniversity of LeedsLeedsUK
- Leeds OmicsUniversity of LeedsLeedsUK
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6
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Ahern ME, Bafaro EM, Cowan A, Dempski RE. Quantifying the Oligomeric State of hZIP4 on the Surface of Cells. Biochemistry 2019; 58:1705-1708. [PMID: 30874431 DOI: 10.1021/acs.biochem.9b00131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human (h) zinc transporter ZIP4 is expressed on the plasma membrane and functions to increase cytosolic zinc levels. Mutations in hZIP4 cause the disease acrodermatitis enteropathica. Dysfunction in the regulation of hZIP4 has also been indicated in solid tissue cancers, including pancreatic and prostate cancer. Although structural studies of the extracellular domain and computational modeling of the membrane domain suggest hZIP4 exists as a dimer, the oligomerization status of hZIP4 in the plasma membrane of mammalian cells has not been directly quantified in vivo. Here, the oligomeric state of hZIP4 expressed in HEK293 cells was quantified using fluorescence correlation spectroscopy. hZIP4 was tagged with eGFP, and by comparing brightness values (ε) of monomer and tandem eGFP constructs to that of an hZIP4/eGFP, we show that hZIP4 is a dimer. Determining that hZIP4 is a dimer is an important step toward understanding the function and processing of the protein, which can provide more insight into how diseases affected by hZIP4 occur and can be managed.
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Affiliation(s)
- Meghan E Ahern
- Department of Chemistry and Biochemistry , Worcester Polytechnic Institute , Worcester , Massachusetts 01609-2247 , United States
| | - Elizabeth M Bafaro
- Department of Chemistry and Biochemistry , Worcester Polytechnic Institute , Worcester , Massachusetts 01609-2247 , United States
| | - Ann Cowan
- Department of Molecular Biology and Biophysics and Center for Cell Analysis and Modeling , University of Connecticut Health Center , Farmington , Connecticut 06030 , United States
| | - Robert E Dempski
- Department of Chemistry and Biochemistry , Worcester Polytechnic Institute , Worcester , Massachusetts 01609-2247 , United States
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7
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Gunther G, Jameson DM, Aguilar J, Sánchez SA. Scanning fluorescence correlation spectroscopy comes full circle. Methods 2018; 140-141:52-61. [DOI: 10.1016/j.ymeth.2018.01.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/23/2018] [Accepted: 01/30/2018] [Indexed: 11/26/2022] Open
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8
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Papini C, Royer CA. Scanning number and brightness yields absolute protein concentrations in live cells: a crucial parameter controlling functional bio-molecular interaction networks. Biophys Rev 2018; 10:87-96. [PMID: 29383593 DOI: 10.1007/s12551-017-0394-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 12/29/2017] [Indexed: 12/27/2022] Open
Abstract
Biological function results from properly timed bio-molecular interactions that transduce external or internal signals, resulting in any number of cellular fates, including triggering of cell-state transitions (division, differentiation, transformation, apoptosis), metabolic homeostasis and adjustment to changing physical or nutritional environments, amongst many more. These bio-molecular interactions can be modulated by chemical modifications of proteins, nucleic acids, lipids and other small molecules. They can result in bio-molecular transport from one cellular compartment to the other and often trigger specific enzyme activities involved in bio-molecular synthesis, modification or degradation. Clearly, a mechanistic understanding of any given high level biological function requires a quantitative characterization of the principal bio-molecular interactions involved and how these may change dynamically. Such information can be obtained using fluctation analysis, in particular scanning number and brightness, and used to build and test mechanistic models of the functional network to define which characteristics are the most important for its regulation.
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Affiliation(s)
- Christina Papini
- Program in Biochemistry and Biophysics, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Catherine A Royer
- Program in Biochemistry and Biophysics, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
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9
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Functional divergence between the two P1-P2 stalk dimers on the ribosome in their interaction with ricin A chain. Biochem J 2014; 460:59-67. [PMID: 24576056 DOI: 10.1042/bj20140014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The eukaryotic stalk, which is responsible for the recruitment of translation factors, is a pentamer containing two P1-P2 dimers with unclear modes of action. In Saccharomyces cerevisiae, P1/P2 proteins (individual P1 and P2 proteins) are organized into two distinct dimers, P1A-P2B and P1B-P2A. To investigate the functional contribution of each dimer on the ribosome, RTA (ricin A chain), which binds to the stalk to depurinate the SRL (sarcin/ricin loop), was used as a molecular probe in yeast mutants in which the binding site for one or the other dimer on P0 was deleted. Ribosome depurination and toxicity of RTA were greatly reduced in mutants containing only P1A-P2B on the ribosome, whereas those with only P1B-P2A were reduced less in depurination and were unaffected in toxicity. Ribosomes bearing P1B-P2A were depurinated by RTA at a similar level as wild-type, but ribosomes bearing P1A-P2B were depurinated at a much lower level in vitro. The latter ribosomes showed the lowest association and almost no dissociation with RTA by surface plasmon resonance. These results indicate that the P1B-P2A dimer is more critical for facilitating the access of RTA to the SRL, providing the first in vivo evidence for functional divergence between the two stalk dimers on the ribosome.
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10
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May KL, Yan Q, Tumer NE. Targeting ricin to the ribosome. Toxicon 2013; 69:143-51. [PMID: 23454625 DOI: 10.1016/j.toxicon.2013.02.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/01/2013] [Accepted: 02/06/2013] [Indexed: 12/15/2022]
Abstract
The plant toxin ricin is highly toxic for mammalian cells and is of concern for bioterrorism. Ricin belongs to a family of functionally related toxins, collectively referred to as ribosome inactivating proteins (RIPs), which disable ribosomes and halt protein synthesis. Currently there are no specific antidotes against ricin or related RIPs. The catalytic subunit of ricin is an N-glycosidase that depurinates a universally conserved adenine residue within the sarcin/ricin loop (SRL) of the 28S rRNA. This depurination activity inhibits translation and its biochemistry has been intensively studied. Yet, recent developments paint a more complex picture of toxicity, with ribosomal proteins and cellular signaling pathways contributing to the potency of ricin. In particular, several studies have now established the importance of the ribosomal stalk structure in facilitating the depurination activity and ribosome specificity of ricin and other RIPs. This review highlights recent developments defining toxin-ribosome interactions and examines the significance of these interactions for toxicity and therapeutic intervention.
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Affiliation(s)
- Kerrie L May
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901-8520, USA
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11
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Cárdenas D, Revuelta-Cervantes J, Jiménez-Díaz A, Camargo H, Remacha M, Ballesta JPG. P1 and P2 protein heterodimer binding to the P0 protein of Saccharomyces cerevisiae is relatively non-specific and a source of ribosomal heterogeneity. Nucleic Acids Res 2012; 40:4520-9. [PMID: 22275522 PMCID: PMC3378876 DOI: 10.1093/nar/gks036] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 01/09/2012] [Accepted: 01/09/2012] [Indexed: 11/18/2022] Open
Abstract
The ribosomal stalk is formed by four acidic phosphoproteins in Saccharomyces cerevisiae, P1α, P1β, P2α and P2β, which form two heterodimers, P1α/P2β and P1β/P2α, that preferentially bind to sites A and B of the P0 protein, respectively. Using mutant strains carrying only one of the four possible P1/P2 combinations, we found a specific phenotype associated to each P1/P2 pair, indicating that not all acidic P proteins play the same role. The absence of one P1/P2 heterodimer reduced the rate of cell growth by varying degrees, depending on the proteins missing. Synthesis of the 60S ribosomal subunit also decreased, particularly in strains carrying the unusual P1α-P2α or P1β-P2β heterodimers, although the distinct P1/P2 dimers are bound with similar affinity to the mutant ribosome. While in wild-type strains the B site bound P1β/P2α in a highly specific manner and the A site bound the four P proteins similarly, both the A and B binding sites efficiently bound practically any P1/P2 pair in mutant strains expressing truncated P0 proteins. The reported results support that while most ribosomes contain a P1α/P2β-P0-P1β/P2α structure in normal conditions, the stalk assembly mechanism can generate alternative compositions, which have been previously detected in the cell.
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Affiliation(s)
| | | | | | | | - Miguel Remacha
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Juan P. G. Ballesta
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain
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12
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Laurdan generalized polarization fluctuations measures membrane packing micro-heterogeneity in vivo. Proc Natl Acad Sci U S A 2012; 109:7314-9. [PMID: 22529342 DOI: 10.1073/pnas.1118288109] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cellular membranes are heterogeneous in composition, and the prevailing theory holds that the structures responsible for this heterogeneity in vivo are small structures (10-200 nm), sterol- and sphingolipid-enriched, of different sizes, highly dynamic denominated rafts. Rafts are postulated to be platforms, which by sequestering different membrane components can compartmentalize cellular processes and regulate signaling pathways. Despite an enormous effort in this area, the existence of these domains is still under debate due to the characteristics of the structures itself: small in size and highly mobile, which from the technical point of view implies using techniques with high spatial and temporal resolution. In this report we measured rapid fluctuations of the normalized ratio of the emission intensity at two wavelengths of Laurdan, a membrane fluorescent dye sensitive to local membrane packing. We observed generalized polarization fluctuations in the plasma membrane of intact rabbit erythrocytes and Chinese hamster ovary cells that can be explained by the existence of tightly packed micro-domains moving in a more fluid background phase. These structures, which display different lipid packing, have different sizes; they are found in the same cell and in the entire cell population. The small size and characteristic high lipid packing indicate that these micro-domains have properties that have been proposed for lipid rafts.
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13
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Sanchez S, Bakás L, Gratton E, Herlax V. Alpha hemolysin induces an increase of erythrocytes calcium: a FLIM 2-photon phasor analysis approach. PLoS One 2011; 6:e21127. [PMID: 21698153 PMCID: PMC3116868 DOI: 10.1371/journal.pone.0021127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 05/19/2011] [Indexed: 12/26/2022] Open
Abstract
α-Hemolysin (HlyA) from Escherichia coli is considered as the prototype of a family of toxins called RTX (repeat in toxin), a group of proteins that share genetic and structural features. HlyA is an important virulence factor in E. coli extraintestinal infections, such as meningitis, septicemia and urinary infections. High concentrations of the toxin cause the lysis of several cells such as erythrocytes, granulocytes, monocytes, endothelial and renal epithelial cells of different species. At low concentrations it induces the production of cytokines and apoptosis. Since many of the subcytolytic effects in other cells have been reported to be triggered by the increase of intracellular calcium, we followed the calcium concentration inside the erythrocytes while incubating with sublytic concentrations of HlyA. Calcium concentration was monitored using the calcium indicator Green 1, 2-photon excitation, and fluorescence lifetime imaging microscopy (FLIM). Data were analyzed using the phasor representation. In this report, we present evidence that, at sublytic concentrations, HlyA induces an increase of calcium concentration in rabbit erythrocytes in the first 10 s. Results are discussed in relation to the difficulties of measuring calcium concentrations in erythrocytes where hemoglobin is present, the contribution of the background and the heterogeneity of the response observed in individual cells.
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Affiliation(s)
- Susana Sanchez
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, California, United States of America
- Microscopy Unit, Fundación CNIC-Carlos III, Centro Nacional de Investigaciones Cardiovasculares, Madrid, España
| | - Laura Bakás
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
- Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, California, United States of America
| | - Vanesa Herlax
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
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Sánchez SA, Tricerri MA, Ossato G, Gratton E. Lipid packing determines protein-membrane interactions: challenges for apolipoprotein A-I and high density lipoproteins. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1798:1399-408. [PMID: 20347719 PMCID: PMC2883020 DOI: 10.1016/j.bbamem.2010.03.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Revised: 03/18/2010] [Accepted: 03/19/2010] [Indexed: 12/16/2022]
Abstract
Protein and protein-lipid interactions, with and within specific areas in the cell membrane, are critical in order to modulate the cell signaling events required to maintain cell functions and viability. Biological bilayers are complex, dynamic platforms, and thus in vivo observations usually need to be preceded by studies on model systems that simplify and discriminate the different factors involved in lipid-protein interactions. Fluorescence microscopy studies using giant unilamellar vesicles (GUVs) as membrane model systems provide a unique methodology to quantify protein binding, interaction, and lipid solubilization in artificial bilayers. The large size of lipid domains obtainable on GUVs, together with fluorescence microscopy techniques, provides the possibility to localize and quantify molecular interactions. Fluorescence Correlation Spectroscopy (FCS) can be performed using the GUV model to extract information on mobility and concentration. Two-photon Laurdan Generalized Polarization (GP) reports on local changes in membrane water content (related to membrane fluidity) due to protein binding or lipid removal from a given lipid domain. In this review, we summarize the experimental microscopy methods used to study the interaction of human apolipoprotein A-I (apoA-I) in lipid-free and lipid-bound conformations with bilayers and natural membranes. Results described here help us to understand cholesterol homeostasis and offer a methodological design suited to different biological systems.
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Affiliation(s)
- Susana A Sánchez
- Laboratory for Fluorescence Dynamics (LFD), University of California at Irvine, Biomedical Engineering Department, Irvine, CA 92697-2715, USA.
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15
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Francisco-Velilla R, Remacha M. In vivo formation of a stable pentameric (P2alpha/P1beta)-P0-(P1alpha/P2beta) ribosomal stalk complex in Saccharomyces cerevisiae. Yeast 2010; 27:693-704. [PMID: 20225338 DOI: 10.1002/yea.1765] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Heterodimers of acidic proteins P1alpha/P2beta and P1beta/P2alpha bind to P0 and are fundamental for the assembly of the ribosomal stalk. However, different inconsistencies are found in the literature regarding additional P protein heterodimer formations and their individual interactions with P0. Using the two-hybrid approach, we have found results that help to clarify these interactions. Thus, we have found that neither P1 nor P2 directly interact with P0 unless the endogenous heterodimer partner is being expressed in the cell. In addition, a P2-free amino end is a requisite in these heterodimers for binding to P0. With regard to the two-hybrid interactions between P1 and P2, the known canonical P1alpha-P2beta and P1beta-P2alpha interactions do not depend on either a free amino end or the presence of endogenous P0, P1 or P2 proteins. Furthermore, the non-canonical P1beta-P2beta pair also behaves similarly, although this interaction is weaker. Interestingly, P1alpha-P2alpha, P1alpha-P1beta and P2alpha-P2beta two-hybrid interactions were also detected, although in these cases the endogenous P proteins were involved. Thus, these positive interactions are the consequence of the interaction between two canonical heterodimers. As the ribosome anchorage protein P0 is also necessary, the results suggest that, in vivo, all five P proteins form a complex, independent of the ribosome, containing the two canonical heterodimers and P0. This complex has been isolated in cells expressing a P0 protein unable to bind to the ribosome.
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Grela P, Krokowski D, Gordiyenko Y, Krowarsch D, Robinson CV, Otlewski J, Grankowski N, Tchórzewski M. Biophysical Properties of the Eukaryotic Ribosomal Stalk. Biochemistry 2010; 49:924-33. [DOI: 10.1021/bi901811s] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Przemysław Grela
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Dawid Krokowski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Yuliya Gordiyenko
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB21EW, United Kingdom
| | - Daniel Krowarsch
- Laboratory of Protein Engineering, University of Wroclaw, Tamka 2, 50-137 Wroclaw, Poland
| | - Carol V. Robinson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB21EW, United Kingdom
| | - Jacek Otlewski
- Laboratory of Protein Engineering, University of Wroclaw, Tamka 2, 50-137 Wroclaw, Poland
| | - Nikodem Grankowski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Marek Tchórzewski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
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Abstract
Movements are implicit in the chromosome behaviors of bouquet formation, pairing and synapsis during meiotic prophase. In S. cerevisiae, the positions of chromosomes, specific structures, and individual chromosomal loci marked by fluorescent fusion proteins are easily visualized in living cells. Time-lapse analyses have revealed rapid and varied chromosome movements throughout meiotic prophase. To facilitate the analysis of these movements, we have developed a simple, inexpensive, and efficient method to prepare sporulating cells for fluorescence microscopy. This method produces a monolayer of cells that progress from meiosis through spore formation, allows visualization of hundreds of cells in a single high-resolution frame and is suitable for most methods of fluorescence microscopy.
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18
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Jameson DM, Ross JA, Albanesi JP. Fluorescence fluctuation spectroscopy: ushering in a new age of enlightenment for cellular dynamics. Biophys Rev 2009; 1:105-118. [PMID: 21547245 DOI: 10.1007/s12551-009-0013-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Originally developed for applications in physics and physical chemistry, fluorescence fluctuation spectroscopy is becoming widely used in cell biology. This review traces the development of the method and describes some of the more important applications. Specifically, the methods discussed include fluorescence correlation spectroscopy (FCS), scanning FCS, dual color cross-correlation FCS, the photon counting histogram and fluorescence intensity distribution analysis approaches, the raster scanning image correlation spectroscopy method, and the Number and Brightness technique. The physical principles underlying these approaches will be delineated, and each of the methods will be illustrated using examples from the literature.
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Affiliation(s)
- David M Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo St., BSB 222, Honolulu, HI 96813, USA
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Current awareness on yeast. Yeast 2008. [DOI: 10.1002/yea.1558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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20
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FUJIWARA K, HIROKAWA S, AOKI M. Comparison of Fluorescence Correlation Spectrometry with the Ordinary Fluorescence Optical Configuration with Flow Cytometry as a Tool for Micrometer-level Size Determination. ANAL SCI 2008; 24:1623-7. [DOI: 10.2116/analsci.24.1623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Kitao FUJIWARA
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences
| | - Shun HIROKAWA
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences
| | - Motohide AOKI
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences
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