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Zhu L, Su Y, Ma S, Guo L, Yang S, Yu H. Comparative Proteomic Analysis Reveals Candidate Pathways Related to the Effect of Different Light Qualities on the Development of Mycelium and Fruiting Body of Pleurotus ostreatus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:1361-1375. [PMID: 38166381 DOI: 10.1021/acs.jafc.3c06083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Light affects the morphology and physiology of Pleurotus ostreatus. However, the underlying molecular mechanism of this effect remains unclear. In this study, a label-free comparative proteomic analysis was conducted to investigate the global protein expression profile of the mycelia and fruiting bodies of P. ostreatus PH11 growing under four different light quality treatments. Among all the 2234 P. ostreatus proteins, 1349 were quantifiable under all tested conditions. A total of 1100 differentially expressed proteins were identified by comparing the light group data with those of the darkness group. GO and KEGG enrichment analyses indicated that the oxidative phosphorylation, proteasome, and mRNA surveillance pathways were the most related pathways under the light condition. qRT-PCR verified that the expression of the white collar 1 protein was significantly enhanced under white light. Additionally, glutamine synthetase and aldehyde dehydrogenase played important roles during light exposure. This study provides valuable insight into the P. ostreatus light response mechanism, which will lay the foundation for improved cultivation.
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Affiliation(s)
- Liping Zhu
- Shandong Provincial Key Laboratory of Applied Mycology, School of Life Sciences, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District, Qingdao, Shandong Province266109, People's Republic of China
| | - Yao Su
- Shandong Provincial Key Laboratory of Applied Mycology, School of Life Sciences, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District, Qingdao, Shandong Province266109, People's Republic of China
| | - Shunan Ma
- Shandong Provincial Key Laboratory of Applied Mycology, School of Life Sciences, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District, Qingdao, Shandong Province266109, People's Republic of China
| | - Lizhong Guo
- Shandong Provincial Key Laboratory of Applied Mycology, School of Life Sciences, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District, Qingdao, Shandong Province266109, People's Republic of China
| | - Song Yang
- Shandong Provincial Key Laboratory of Applied Mycology, School of Life Sciences, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District, Qingdao, Shandong Province266109, People's Republic of China
| | - Hao Yu
- Shandong Provincial Key Laboratory of Applied Mycology, School of Life Sciences, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District, Qingdao, Shandong Province266109, People's Republic of China
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2
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Agrotis A, Lamoliatte F, Williams TD, Black A, Horberry R, Rousseau A. Multiple phosphorylation of the Cdc48/p97 cofactor protein Shp1/p47 occurs upon cell stress in budding yeast. Life Sci Alliance 2023; 6:e202201642. [PMID: 36693698 PMCID: PMC9874129 DOI: 10.26508/lsa.202201642] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 01/16/2023] [Accepted: 01/16/2023] [Indexed: 01/26/2023] Open
Abstract
The homohexameric p97 complex, composed of Cdc48 subunits in yeast, is a crucial component of protein quality control pathways including ER-associated degradation. The complex acts to segregate protein complexes in an ATP-dependent manner, requiring the engagement of cofactor proteins that determine substrate specificity. The function of different Cdc48 cofactors and how they are regulated remains relatively poorly understood. In this study, we assess the phosphorylation of Cdc48 adaptor proteins, revealing a unique and distinctive phosphorylation pattern of Shp1/p47 that changed in response to TORC1 inhibition. Site-directed mutagenesis confirmed that this pattern corresponded to phosphorylation at residues S108 and S315 of Shp1, with the double-phosphorylated form becoming predominant upon TORC1 inhibition, ER-stress, and oxidative stress. Finally, we assessed candidate kinases and phosphatases responsible for Shp1 phosphorylation and identified two regulators. We found that cells lacking the kinase Mpk1/Slt2 show reduced Shp1 phosphorylation, whereas impaired PP1 phosphatase catalytic subunit (Glc7) activity resulted in increased Shp1 phosphorylation. Overall, these findings identify a phosphoregulation of Shp1 at multiple sites by Mpk1 kinase and PP1 phosphatase upon various stresses.
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Affiliation(s)
- Alexander Agrotis
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Frederic Lamoliatte
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Thomas D Williams
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Ailsa Black
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Rhuari Horberry
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Adrien Rousseau
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
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3
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Kocakaplan D, Karabürk H, Dilege C, Kirdök I, Bektas SN, Caydasi AK. Protein phosphatase 1 in association with Bud14 inhibits mitotic exit in Saccharomyces cerevisiae. eLife 2021; 10:72833. [PMID: 34633288 PMCID: PMC8577847 DOI: 10.7554/elife.72833] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/08/2021] [Indexed: 11/18/2022] Open
Abstract
Mitotic exit in budding yeast is dependent on correct orientation of the mitotic spindle along the cell polarity axis. When accurate positioning of the spindle fails, a surveillance mechanism named the spindle position checkpoint (SPOC) prevents cells from exiting mitosis. Mutants with a defective SPOC become multinucleated and lose their genomic integrity. Yet, a comprehensive understanding of the SPOC mechanism is missing. In this study, we identified the type 1 protein phosphatase, Glc7, in association with its regulatory protein Bud14 as a novel checkpoint component. We further showed that Glc7-Bud14 promotes dephosphorylation of the SPOC effector protein Bfa1. Our results suggest a model in which two mechanisms act in parallel for a robust checkpoint response: first, the SPOC kinase Kin4 isolates Bfa1 away from the inhibitory kinase Cdc5, and second, Glc7-Bud14 dephosphorylates Bfa1 to fully activate the checkpoint effector.
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Affiliation(s)
- Dilara Kocakaplan
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Hüseyin Karabürk
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Cansu Dilege
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Idil Kirdök
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Seyma Nur Bektas
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Ayse Koca Caydasi
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
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4
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Berkes C, Franco J, Lawson M, Brann K, Mermelstein J, Laverty D, Connors A. Kinase Inhibitor Library Screening Identifies the Cancer Therapeutic Sorafenib and Structurally Similar Compounds as Strong Inhibitors of the Fungal Pathogen Histoplasma capsulatum. Antibiotics (Basel) 2021; 10:antibiotics10101223. [PMID: 34680804 PMCID: PMC8532743 DOI: 10.3390/antibiotics10101223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/17/2021] [Accepted: 09/24/2021] [Indexed: 12/01/2022] Open
Abstract
Histoplasma capsulatum is a dimorphic fungal pathogen endemic to the midwestern and southern United States. It causes mycoses ranging from subclinical respiratory infections to severe systemic disease, and is of particular concern for immunocompromised patients in endemic areas. Clinical management of histoplasmosis relies on protracted regimens of antifungal drugs whose effectiveness can be limited by toxicity. In this study, we hypothesize that conserved biochemical signaling pathways in the eukaryotic domain can be leveraged to repurpose kinase inhibitors as antifungal compounds. We conducted a screen of two kinase inhibitor libraries to identify compounds inhibiting the growth of Histoplasma capsulatum in the pathogenic yeast form. Our approach identified seven compounds with an elongated hydrophobic polyaromatic structure, five of which share a molecular motif including a urea unit linking a halogenated benzene ring and a para-substituted polyaromatic group. The top hits include the cancer therapeutic Sorafenib, which inhibits growth of Histoplasma in vitro and in a macrophage infection model with low host cell cytotoxicity. Our results reveal the possibility of repurposing Sorafenib or derivatives thereof as therapy for histoplasmosis, and suggest that repurposing of libraries developed for human cellular targets may be a fruitful source of antifungal discovery.
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Affiliation(s)
- Charlotte Berkes
- Department of Biology, Merrimack College, North Andover, MA 01845, USA; (M.L.); (K.B.); (J.M.); (D.L.)
- Correspondence:
| | - Jimmy Franco
- Department of Chemistry and Biochemistry, Merrimack College, North Andover, MA 01845, USA; (J.F.); (A.C.)
| | - Maxx Lawson
- Department of Biology, Merrimack College, North Andover, MA 01845, USA; (M.L.); (K.B.); (J.M.); (D.L.)
| | - Katelynn Brann
- Department of Biology, Merrimack College, North Andover, MA 01845, USA; (M.L.); (K.B.); (J.M.); (D.L.)
| | - Jessica Mermelstein
- Department of Biology, Merrimack College, North Andover, MA 01845, USA; (M.L.); (K.B.); (J.M.); (D.L.)
| | - Daniel Laverty
- Department of Biology, Merrimack College, North Andover, MA 01845, USA; (M.L.); (K.B.); (J.M.); (D.L.)
- Department of Chemistry and Biochemistry, Merrimack College, North Andover, MA 01845, USA; (J.F.); (A.C.)
| | - Allison Connors
- Department of Chemistry and Biochemistry, Merrimack College, North Andover, MA 01845, USA; (J.F.); (A.C.)
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Transcriptional regulatory proteins in central carbon metabolism of Pichia pastoris and Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2020; 104:7273-7311. [PMID: 32651601 DOI: 10.1007/s00253-020-10680-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 05/04/2020] [Accepted: 05/10/2020] [Indexed: 01/21/2023]
Abstract
System-wide interactions in living cells and discovery of the diverse roles of transcriptional regulatory proteins that are mediator proteins with catalytic domains and regulatory subunits and transcription factors in the cellular pathways have become crucial for understanding the cellular response to environmental conditions. This review provides information for future metabolic engineering strategies through analyses on the highly interconnected regulatory networks in Saccharomyces cerevisiae and Pichia pastoris and identifying their components. We discuss the current knowledge on the carbon catabolite repression (CCR) mechanism, interconnecting regulatory system of the central metabolic pathways that regulate cell metabolism based on nutrient availability in the industrial yeasts. The regulatory proteins and their functions in the CCR signalling pathways in both yeasts are presented and discussed. We highlight the importance of metabolic signalling networks by signifying ways on how effective engineering strategies can be designed for generating novel regulatory circuits, furthermore to activate pathways that reconfigure the network architecture. We summarize the evidence that engineering of multilayer regulation is needed for directed evolution of the cellular network by putting the transcriptional control into a new perspective for the regulation of central carbon metabolism of the industrial yeasts; furthermore, we suggest research directions that may help to enhance production of recombinant products in the widely used, creatively engineered, but relatively less studied P. pastoris through de novo metabolic engineering strategies based on the discovery of components of signalling pathways in CCR metabolism. KEY POINTS: • Transcriptional regulation and control is the key phenomenon in the cellular processes. • Designing de novo metabolic engineering strategies depends on the discovery of signalling pathways in CCR metabolism. • Crosstalk between pathways occurs through essential parts of transcriptional machinery connected to specific catalytic domains. • In S. cerevisiae, a major part of CCR metabolism is controlled through Snf1 kinase, Glc7 phosphatase, and Srb10 kinase. • In P. pastoris, signalling pathways in CCR metabolism have not yet been clearly known yet. • Cellular regulations on the transcription of promoters are controlled with carbon sources.
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6
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Ruggiero A, Katou Y, Shirahige K, Séveno M, Piatti S. The Phosphatase PP1 Promotes Mitotic Slippage through Mad3 Dephosphorylation. Curr Biol 2020; 30:335-343.e5. [PMID: 31928870 DOI: 10.1016/j.cub.2019.11.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 10/04/2019] [Accepted: 11/18/2019] [Indexed: 11/17/2022]
Abstract
Accurate chromosome segregation requires bipolar attachment of kinetochores to spindle microtubules. A conserved surveillance mechanism, the spindle assembly checkpoint (SAC), responds to lack of kinetochore-microtubule connections and delays anaphase onset until all chromosomes are bipolarly attached [1]. SAC signaling fires at kinetochores and involves a soluble mitotic checkpoint complex (MCC) that inhibits the anaphase-promoting complex (APC) [2, 3]. The mitotic delay imposed by SAC, however, is not everlasting. If kinetochores fail to establish bipolar connections, cells can escape from the SAC-induced mitotic arrest through a process called mitotic slippage [4]. Mitotic slippage occurs in the presence of SAC signaling at kinetochores [5, 6], but whether and how MCC stability and APC inhibition are actively controlled during slippage is unknown. The PP1 phosphatase has emerged as a key factor in SAC silencing once all kinetochores are bipolarly attached [7, 8]. PP1 turns off SAC signaling through dephosphorylation of the SAC scaffold Knl1/Blinkin at kinetochores [9-11]. Here, we show that, in budding yeast, PP1 is also required for mitotic slippage. However, its involvement in this process is not linked to kinetochores but rather to MCC stability. We identify S268 of Mad3 as a critical target of PP1 in this process. Mad3 S268 dephosphorylation destabilizes the MCC without affecting the initial SAC-induced mitotic arrest. Conversely, it accelerates mitotic slippage and overcomes the slippage defect of PP1 mutants. Thus, slippage is not the mere consequence of incomplete APC inactivation that brings about mitotic exit, as originally proposed, but involves the exertive antagonism between kinases and phosphatases.
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Affiliation(s)
- Antonella Ruggiero
- CRBM, University of Montpellier, CNRS, 1919 Route de Mende, 34293 Montpellier, France
| | - Yuki Katou
- Research Center for Epigenetic Disease, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-0032 Tokyo, Japan
| | - Katsuhiko Shirahige
- Research Center for Epigenetic Disease, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-0032 Tokyo, Japan
| | - Martial Séveno
- BioCampus Montpellier, CNRS, INSERM, University of Montpellier, 34000 Montpellier, France
| | - Simonetta Piatti
- CRBM, University of Montpellier, CNRS, 1919 Route de Mende, 34293 Montpellier, France.
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7
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Kedziora S, Gali VK, Wilson RHC, Clark KRM, Nieduszynski CA, Hiraga SI, Donaldson AD. Rif1 acts through Protein Phosphatase 1 but independent of replication timing to suppress telomere extension in budding yeast. Nucleic Acids Res 2018; 46:3993-4003. [PMID: 29529242 PMCID: PMC5934629 DOI: 10.1093/nar/gky132] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 02/09/2018] [Accepted: 02/23/2018] [Indexed: 12/24/2022] Open
Abstract
The Rif1 protein negatively regulates telomeric TG repeat length in the budding yeast Saccharomyces cerevisiae, but how it prevents telomere over-extension is unknown. Rif1 was recently shown to control DNA replication by acting as a Protein Phosphatase 1 (PP1)-targeting subunit. Therefore, we investigated whether Rif1 controls telomere length by targeting PP1 activity. We find that a Rif1 mutant defective for PP1 interaction causes a long-telomere phenotype, similar to that of rif1Δ cells. Tethering PP1 at a specific telomere partially substitutes for Rif1 in limiting TG repeat length, confirming the importance of PP1 in telomere length control. Ablating Rif1-PP1 interaction is known to cause precocious activation of telomere-proximal replication origins and aberrantly early telomere replication. However, we find that Rif1 still limits telomere length even if late replication is forced through deletion of nearby replication origins, indicating that Rif1 can control telomere length independent of replication timing. Moreover we find that, even at a de novo telomere created after DNA synthesis during a mitotic block, Rif1-PP1 interaction is required to suppress telomere lengthening and prevent inappropriate recruitment of Tel1 kinase. Overall, our results show that Rif1 controls telomere length by recruiting PP1 to directly suppress telomerase-mediated TG repeat lengthening.
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Affiliation(s)
- Sylwia Kedziora
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Vamsi K Gali
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Rosemary HC Wilson
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Kate RM Clark
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Conrad A Nieduszynski
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Shin-ichiro Hiraga
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Anne D Donaldson
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
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8
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Mischo HE, Chun Y, Harlen KM, Smalec BM, Dhir S, Churchman LS, Buratowski S. Cell-Cycle Modulation of Transcription Termination Factor Sen1. Mol Cell 2018; 70:312-326.e7. [PMID: 29656924 PMCID: PMC5919780 DOI: 10.1016/j.molcel.2018.03.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 06/26/2017] [Accepted: 03/08/2018] [Indexed: 01/14/2023]
Abstract
Many non-coding transcripts (ncRNA) generated by RNA polymerase II in S. cerevisiae are terminated by the Nrd1-Nab3-Sen1 complex. However, Sen1 helicase levels are surprisingly low compared with Nrd1 and Nab3, raising questions regarding how ncRNA can be terminated in an efficient and timely manner. We show that Sen1 levels increase during the S and G2 phases of the cell cycle, leading to increased termination activity of NNS. Overexpression of Sen1 or failure to modulate its abundance by ubiquitin-proteasome-mediated degradation greatly decreases cell fitness. Sen1 toxicity is suppressed by mutations in other termination factors, and NET-seq analysis shows that its overexpression leads to a decrease in ncRNA production and altered mRNA termination. We conclude that Sen1 levels are carefully regulated to prevent aberrant termination. We suggest that ncRNA levels and coding gene transcription termination are modulated by Sen1 to fulfill critical cell cycle-specific functions. Transcription termination factor Sen1 levels fluctuate throughout the cell cycle APC targets Sen1 for degradation during G1 Reduced Sen1 levels lower efficiency of Sen1-mediated termination Sen1 overexpression reduces cell viability because of excessive termination
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Affiliation(s)
- Hannah E Mischo
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Sir William Dunn School of Pathology, Oxford University, South Parks Road, Oxford OX1 3RE, UK; Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, UK.
| | - Yujin Chun
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Kevin M Harlen
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Brendan M Smalec
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Somdutta Dhir
- Sir William Dunn School of Pathology, Oxford University, South Parks Road, Oxford OX1 3RE, UK
| | | | - Stephen Buratowski
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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9
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Yurko NM, Manley JL. The RNA polymerase II CTD "orphan" residues: Emerging insights into the functions of Tyr-1, Thr-4, and Ser-7. Transcription 2017; 9:30-40. [PMID: 28771071 DOI: 10.1080/21541264.2017.1338176] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The C-terminal domain (CTD) of the RNA polymerase II largest subunit consists of a unique repeated heptad sequence of the consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. An important function of the CTD is to couple transcription with RNA processing reactions that occur during the initiation, elongation, and termination phases of transcription. During this transcription cycle, the CTD is subject to extensive modification, primarily phosphorylation, on its non-proline residues. Reversible phosphorylation of Ser2 and Ser5 is well known to play important and general functions during transcription in all eukaryotes. More recent studies have enhanced our understanding of Tyr1, Thr4, and Ser7, and what have been previously characterized as unknown or specialized functions for these residues has changed to a more fine-detailed map of transcriptional regulation that highlights similarities as well as significant differences between organisms. Here, we review recent findings on the function and modification of these three residues, which further illustrate the importance of the CTD in precisely modulating gene expression.
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Affiliation(s)
- Nathan M Yurko
- a Department of Biological Sciences , Columbia University , New York , NY , USA
| | - James L Manley
- a Department of Biological Sciences , Columbia University , New York , NY , USA
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10
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Xie JL, Qin L, Miao Z, Grys BT, Diaz JDLC, Ting K, Krieger JR, Tong J, Tan K, Leach MD, Ketela T, Moran MF, Krysan DJ, Boone C, Andrews BJ, Selmecki A, Ho Wong K, Robbins N, Cowen LE. The Candida albicans transcription factor Cas5 couples stress responses, drug resistance and cell cycle regulation. Nat Commun 2017; 8:499. [PMID: 28894103 PMCID: PMC5593949 DOI: 10.1038/s41467-017-00547-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 07/06/2017] [Indexed: 12/16/2022] Open
Abstract
The capacity to coordinate environmental sensing with initiation of cellular responses underpins microbial survival and is crucial for virulence and stress responses in microbial pathogens. Here we define circuitry that enables the fungal pathogen Candida albicans to couple cell cycle dynamics with responses to cell wall stress induced by echinocandins, a front-line class of antifungal drugs. We discover that the C. albicans transcription factor Cas5 is crucial for proper cell cycle dynamics and responses to echinocandins, which inhibit β-1,3-glucan synthesis. Cas5 has distinct transcriptional targets under basal and stress conditions, is activated by the phosphatase Glc7, and can regulate the expression of target genes in concert with the transcriptional regulators Swi4 and Swi6. Thus, we illuminate a mechanism of transcriptional control that couples cell wall integrity with cell cycle regulation, and uncover circuitry governing antifungal drug resistance.Cas5 is a transcriptional regulator of responses to cell wall stress in the fungal pathogen Candida albicans. Here, Xie et al. show that Cas5 also modulates cell cycle dynamics and responses to antifungal drugs.
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Affiliation(s)
- Jinglin L Xie
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
| | - Longguang Qin
- Faculty of Health Sciences, University of Macau, Macau SAR, 999078, China
| | - Zhengqiang Miao
- Faculty of Health Sciences, University of Macau, Macau SAR, 999078, China
| | - Ben T Grys
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada, M5S 3E1
| | - Jacinto De La Cruz Diaz
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, 14642, USA
| | - Kenneth Ting
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
| | - Jonathan R Krieger
- The Hospital for Sick Children, SPARC Biocentre, Toronto, ON, Canada, M5G 0A4
| | - Jiefei Tong
- The Hospital for Sick Children, Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada, M5G 0A4
| | - Kaeling Tan
- Faculty of Health Sciences, University of Macau, Macau SAR, 999078, China
| | - Michelle D Leach
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Abderdeen, AB252ZD, UK
| | - Troy Ketela
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
| | - Michael F Moran
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
- The Hospital for Sick Children, SPARC Biocentre, Toronto, ON, Canada, M5G 0A4
- The Hospital for Sick Children, Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada, M5G 0A4
| | - Damian J Krysan
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, 14642, USA
- Department of Pediatrics and Microbiology/Immunology, University of Rochester, Rochester, NY, 14642, USA
| | - Charles Boone
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada, M5S 3E1
| | - Brenda J Andrews
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada, M5S 3E1
| | - Anna Selmecki
- Department of Medical Microbiology and Immunology, Creighton University School of Medicine, Omaha, NE, 68178, USA
| | - Koon Ho Wong
- Faculty of Health Sciences, University of Macau, Macau SAR, 999078, China
| | - Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5G 1M1.
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11
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De Carvalho FO, Silva ÉR, Felipe FA, Teixeira LGB, Zago LBS, Nunes PS, Shanmugam S, Serafini MR, Araújo AADS. Natural and synthetic products used for the treatment of smoke inhalation: a patent review. Expert Opin Ther Pat 2017; 27:877-886. [DOI: 10.1080/13543776.2017.1339790] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | - Érika Ramos Silva
- Post-graduate Program in Health Sciences, Federal University of Sergipe, São Cristóvão, Brazil
| | - Fernanda Araújo Felipe
- Post-graduate Program in Health Sciences, Federal University of Sergipe, São Cristóvão, Brazil
| | | | | | - Paula Santos Nunes
- Department of Morphology, Federal University of Sergipe, São Cristóvão, Brazil
| | - Saravanan Shanmugam
- Department of Pharmacy, Federal University of Sergipe, São Cristóvão, Brazil
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12
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Jöhnk B, Bayram Ö, Abelmann A, Heinekamp T, Mattern DJ, Brakhage AA, Jacobsen ID, Valerius O, Braus GH. SCF Ubiquitin Ligase F-box Protein Fbx15 Controls Nuclear Co-repressor Localization, Stress Response and Virulence of the Human Pathogen Aspergillus fumigatus. PLoS Pathog 2016; 12:e1005899. [PMID: 27649508 PMCID: PMC5029927 DOI: 10.1371/journal.ppat.1005899] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 08/26/2016] [Indexed: 01/27/2023] Open
Abstract
F-box proteins share the F-box domain to connect substrates of E3 SCF ubiquitin RING ligases through the adaptor Skp1/A to Cul1/A scaffolds. F-box protein Fbx15 is part of the general stress response of the human pathogenic mold Aspergillus fumigatus. Oxidative stress induces a transient peak of fbx15 expression, resulting in 3x elevated Fbx15 protein levels. During non-stress conditions Fbx15 is phosphorylated and F-box mediated interaction with SkpA preferentially happens in smaller subpopulations in the cytoplasm. The F-box of Fbx15 is required for an appropriate oxidative stress response, which results in rapid dephosphorylation of Fbx15 and a shift of the cellular interaction with SkpA to the nucleus. Fbx15 binds SsnF/Ssn6 as part of the RcoA/Tup1-SsnF/Ssn6 co-repressor and is required for its correct nuclear localization. Dephosphorylated Fbx15 prevents SsnF/Ssn6 nuclear localization and results in the derepression of gliotoxin gene expression. fbx15 deletion mutants are unable to infect immunocompromised mice in a model for invasive aspergillosis. Fbx15 has a novel dual molecular function by controlling transcriptional repression and being part of SCF E3 ubiquitin ligases, which is essential for stress response, gliotoxin production and virulence in the opportunistic human pathogen A. fumigatus. The opportunistic human fungal pathogen Aspergillus fumigatus is the most prevalent cause for severe fungal infections in immunocompromised hosts. A major virulence factor of A. fumigatus is its ability to rapidly adapt to host conditions during infection. The rapid response to environmental changes underlies a well-balanced system of production and degradation of proteins. The degradation of specific target proteins is mediated by ubiquitin-protein ligases (E3), which mark their target proteins with ubiquitin for proteasomal degradation. Multisubunit SCF Cullin1 Ring ligases (CRL) are E3 ligases where the F-box subunit functions as a substrate-specificity determining adaptor. A comprehensive control of protein production includes global co-repressors as the conserved Ssn6(SsnF)-Tup1(RcoA) complex, which reduces transcription on multiple levels. We have identified a novel connection between protein degradation and synthesis through an F-box protein. Fbx15 can be incorporated into SCF E3 ubiquitin ligases and controls upon stress the nuclear localization of the SsnF. Fbx15 plays a critical role for A. fumigatus adaptation and is essential for virulence in a murine infection model. Fbx15 is a fungal-specific protein and therefore a potential target for future drug development.
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Affiliation(s)
- Bastian Jöhnk
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Özgür Bayram
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
- Department of Biology, Maynooth University, National University of Ireland, Maynooth, County Kildare, Ireland
| | - Anja Abelmann
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Thorsten Heinekamp
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Derek J. Mattern
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Axel A. Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Ilse D. Jacobsen
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
- * E-mail:
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Orii M, Kono K, Wen HI, Nakanishi M. PP1-Dependent Formin Bnr1 Dephosphorylation and Delocalization from a Cell Division Site. PLoS One 2016; 11:e0146941. [PMID: 26771880 PMCID: PMC4714816 DOI: 10.1371/journal.pone.0146941] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/23/2015] [Indexed: 02/07/2023] Open
Abstract
Cell cycle ends with cytokinesis that is the physical separation of a cell into two daughter cells. For faithful cytokinesis, cells integrate multiple processes, such as actomyosin ring formation, contraction and plasma membrane closure, into coherent responses. Linear actin assembly by formins is essential for formation and maintenance of actomyosin ring. Although budding yeast’s two formins, Bni1 and Bnr1, are known to switch their subcellular localization at the division site prior to cytokinesis, the underlying mechanisms were not completely understood. Here, we provide evidence showing that Bnr1 is dephosphorylated concomitant with its release from the division site. Impaired PP1/Glc7 activity delayed Bnr1 release and dephosphorylation, Bni1 recruitment and actomyosin ring formation at the division site. These results suggest the involvement of Glc7 in this regulation. Further, we identified Ref2 as the PP1 regulatory subunit responsible for this regulation. Taken together, Glc7 and Ref2 may have a role in actomyosin ring formation by modulating the localization of formins during cytokinesis.
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Affiliation(s)
- Minami Orii
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
| | - Keiko Kono
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
- * E-mail: (MN); (KK)
| | - Hsin-I Wen
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
| | - Makoto Nakanishi
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
- * E-mail: (MN); (KK)
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14
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Albataineh MT, Kadosh D. Regulatory roles of phosphorylation in model and pathogenic fungi. Med Mycol 2015; 54:333-52. [PMID: 26705834 PMCID: PMC4818690 DOI: 10.1093/mmy/myv098] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 11/01/2015] [Indexed: 12/25/2022] Open
Abstract
Over the past 20 years, considerable advances have been made toward our understanding
of how post-translational modifications affect a wide variety of biological
processes, including morphology and virulence, in medically important fungi.
Phosphorylation stands out as a key molecular switch and regulatory modification that
plays a critical role in controlling these processes. In this article, we first
provide a comprehensive and up-to-date overview of the regulatory roles that both
Ser/Thr and non-Ser/Thr kinases and phosphatases play in model and pathogenic fungi.
Next, we discuss the impact of current global approaches that are being used to
define the complete set of phosphorylation targets (phosphoproteome) in medically
important fungi. Finally, we provide new insights and perspectives into the potential
use of key regulatory kinases and phosphatases as targets for the development of
novel and more effective antifungal strategies.
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Affiliation(s)
- Mohammad T Albataineh
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - David Kadosh
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
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15
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Pérez P, Portales E, Santos B. Rho4 interaction with exocyst and septins regulates cell separation in fission yeast. MICROBIOLOGY-SGM 2015; 161:948-959. [PMID: 25724972 DOI: 10.1099/mic.0.000062] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/18/2015] [Indexed: 12/17/2022]
Abstract
Rho GTPases are small proteins present in all eukaryotic cells, from yeast to mammals, with a function in actin organization and morphogenetic processes. Schizosaccharomyces pombe Rho4 is not essential but it displays a role during cell separation at high temperature. In fact, Rho4 is involved in the secretion of the hydrolytic enzymes that are required for cell septum degradation during this process. In rho4Δ cells, vesicles accumulate in the septum area and the glucanases Eng1 and Agn1 are not secreted to the culture medium. The localization of Eng1 and Agn1 depends on the exocyst and the septins. The exocyst is a conserved multiprotein complex important for the targeting and fusion of Golgi-derived vesicles with the plasma membrane. Septins are a family of GTP-binding proteins conserved in eukaryotes that function during cytokinesis. Here we show that Rho4 is required for the proper localization of the exocyst and septins at high temperature. Moreover, pull-down experiments demonstrate that Rho4 can interact with exocyst subunits, such as Sec8 and Exo70, and septin proteins, such as Spn3. We observe that Sec8 preferentially binds to activated GTP-Rho4, suggesting that Sec8 could be an effector of this GTPase. We propose that the interaction of Rho4 with the exocyst and septins confers a precise regulation for the secretion of glucanases at the appropriate place and time during the cell cycle.
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Affiliation(s)
- Pilar Pérez
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
| | - Elvira Portales
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
| | - Beatriz Santos
- Departamento de Microbiología y Genética, Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain.,Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
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16
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Liesche J, Marek M, Günther-Pomorski T. Cell wall staining with Trypan blue enables quantitative analysis of morphological changes in yeast cells. Front Microbiol 2015; 6:107. [PMID: 25717323 PMCID: PMC4324143 DOI: 10.3389/fmicb.2015.00107] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 01/27/2015] [Indexed: 11/13/2022] Open
Abstract
Yeast cells are protected by a cell wall that plays an important role in the exchange of substances with the environment. The cell wall structure is dynamic and can adapt to different physiological states or environmental conditions. For the investigation of morphological changes, selective staining with fluorescent dyes is a valuable tool. Furthermore, cell wall staining is used to facilitate sub-cellular localization experiments with fluorescently-labeled proteins and the detection of yeast cells in non-fungal host tissues. Here, we report staining of Saccharomyces cerevisiae cell wall with Trypan Blue, which emits strong red fluorescence upon binding to chitin and yeast glucan; thereby, it facilitates cell wall analysis by confocal and super-resolution microscopy. The staining pattern of Trypan Blue was similar to that of the widely used UV-excitable, blue fluorescent cell wall stain Calcofluor White. Trypan Blue staining facilitated quantification of cell size and cell wall volume when utilizing the optical sectioning capacity of a confocal microscope. This enabled the quantification of morphological changes during growth under anaerobic conditions and in the presence of chemicals, demonstrating the potential of this approach for morphological investigations or screening assays.
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Affiliation(s)
- Johannes Liesche
- Department of Plant and Environmental Sciences, University of Copenhagen Copenhagen, Denmark
| | - Magdalena Marek
- Department of Plant and Environmental Sciences, University of Copenhagen Copenhagen, Denmark
| | - Thomas Günther-Pomorski
- Department of Plant and Environmental Sciences, University of Copenhagen Copenhagen, Denmark
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17
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Hiraga SI, Alvino GM, Chang F, Lian HY, Sridhar A, Kubota T, Brewer BJ, Weinreich M, Raghuraman MK, Donaldson AD. Rif1 controls DNA replication by directing Protein Phosphatase 1 to reverse Cdc7-mediated phosphorylation of the MCM complex. Genes Dev 2014; 28:372-83. [PMID: 24532715 PMCID: PMC3937515 DOI: 10.1101/gad.231258.113] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Initiation of eukaryotic DNA replication requires phosphorylation of the MCM complex by Dbf4-dependent kinase (DDK), composed of Cdc7 kinase and its activator, Dbf4. We report here that budding yeast Rif1 (Rap1-interacting factor 1) controls DNA replication genome-wide and describe how Rif1 opposes DDK function by directing Protein Phosphatase 1 (PP1)-mediated dephosphorylation of the MCM complex. Deleting RIF1 partially compensates for the limited DDK activity in a cdc7-1 mutant strain by allowing increased, premature phosphorylation of Mcm4. PP1 interaction motifs within the Rif1 N-terminal domain are critical for its repressive effect on replication. We confirm that Rif1 interacts with PP1 and that PP1 prevents premature Mcm4 phosphorylation. Remarkably, our results suggest that replication repression by Rif1 is itself also DDK-regulated through phosphorylation near the PP1-interacting motifs. Based on our findings, we propose that Rif1 is a novel PP1 substrate targeting subunit that counteracts DDK-mediated phosphorylation during replication. Fission yeast and mammalian Rif1 proteins have also been implicated in regulating DNA replication. Since PP1 interaction sites are evolutionarily conserved within the Rif1 sequence, it is likely that replication control by Rif1 through PP1 is a conserved mechanism.
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Affiliation(s)
- Shin-Ichiro Hiraga
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
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18
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Biochemical properties and possible roles of ectophosphatase activities in fungi. Int J Mol Sci 2014; 15:2289-304. [PMID: 24509700 PMCID: PMC3958851 DOI: 10.3390/ijms15022289] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/27/2013] [Accepted: 01/14/2014] [Indexed: 12/31/2022] Open
Abstract
Ectophosphatases are surface membrane-bound proteins whose active sites face the extracellular medium. These enzymes have been reported in several microorganisms including a large number of medically relevant fungal species. An effective technique for identifying ectophosphatases is performing phosphatase activity assays using living intact cells. Biochemical characterization of these activities has shown their differential modulation by classical phosphatase inhibitors, divalent metals and pH range. The physiological roles of ectophosphatases are not well established; however, it has been suggested that these enzymes play important roles in nutrition, proliferation, differentiation, adhesion, virulence and infection. Adhesion to host cells is the first step in establishing a fungal infection and ectophosphatases may be one of the first parasite proteins that come into contact with the host cells. Several results indicate that ectophosphatase activities increase the capacity of fungi to adhere to the host cells. In this context, the present review provides an overview of recent discoveries related to the occurrence and possible roles of ectophosphatase activities in fungal cells.
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19
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Freitas-Mesquita AL, Meyer-Fernandes JR. Ecto-nucleotidases and Ecto-phosphatases from Leishmania and Trypanosoma parasites. Subcell Biochem 2014; 74:217-252. [PMID: 24264248 DOI: 10.1007/978-94-007-7305-9_10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ecto-enzymes can be defined as membrane-bound proteins that have their active site facing the extracellular millieu. In trypanosomatids, the physiological roles of these enzymes remain to be completed elucidated; however, many important events have already been related to them, such as the survival of parasites during their complex life cycle and the successful establishment of host infection. This chapter focuses on two remarkable classes of ecto-enzymes: ecto-nucleotidases and ecto-phosphatases, summarizing their occurrence and possible physiological roles in Leishmania and Trypanosoma genera. Ecto-nucleotidases are characterized by their ability to hydrolyze extracellular nucleotides, playing an important role in purinergic signaling. By the action of these ecto-enzymes, parasites are capable of modulating the host immune system, which leads to a successful parasite infection. Furthermore, ecto-nucleotidases are also involved in the purine salvage pathway, acting in the generation of nucleosides that are able to cross plasma membrane via specialized transporters. Another important ecto-enzyme present in a vast number of pathogenic organisms is the ecto-phosphatase. These enzymes are able to hydrolyze extracellular phosphorylated substrates, releasing free inorganic phosphate that can be internalized by the cell, crossing the plasma membrane through a Pi-transporter. Ecto-phosphatases are also involved in the invasion and survival of parasite in the host cells. Several alternative functions have been suggested for these enzymes in parasites, such as participation in their proliferation, differentiation, nutrition and protection. In this context, the present chapter provides an overview of recent discoveries related to the occurrence of ecto-nucleotidase and ecto-phosphatase activities in Leishmania and Trypanosoma parasites.
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20
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Good PD, Kendall A, Ignatz-Hoover J, Miller EL, Pai DA, Rivera SR, Carrick B, Engelke DR. Silencing near tRNA genes is nucleosome-mediated and distinct from boundary element function. Gene 2013; 526:7-15. [PMID: 23707796 PMCID: PMC3745993 DOI: 10.1016/j.gene.2013.05.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 01/22/2023]
Abstract
Transfer RNA (tRNA) genes and other RNA polymerase III transcription units are dispersed in high copy throughout nuclear genomes, and can antagonize RNA polymerase II transcription in their immediate chromosomal locus. Previous work in Saccharomyces cerevisiae found that this local silencing required subnuclear clustering of the tRNA genes near the nucleolus. Here we show that the silencing also requires nucleosome participation, though the nature of the nucleosome interaction appears distinct from other forms of transcriptional silencing. Analysis of an extensive library of histone amino acid substitutions finds a large number of residues that affect the silencing, both in the histone N-terminal tails and on the nucleosome disk surface. The residues on the disk surfaces involved are largely distinct from those affecting other regulatory phenomena. Consistent with the large number of histone residues affecting tgm silencing, survey of chromatin modification mutations shows that several enzymes known to affect nucleosome modification and positioning are also required. The enzymes include an Rpd3 deacetylase complex, Hos1 deacetylase, Glc7 phosphatase, and the RSC nucleosome remodeling activity, but not multiple other activities required for other silencing forms or boundary element function at tRNA gene loci. Models for communication between the tRNA gene transcription complexes and local chromatin are discussed.
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Affiliation(s)
- Paul D. Good
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109-0600, USA
| | - Ann Kendall
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109-0600, USA
| | | | - Erin L. Miller
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109-0600, USA
| | - Dave A. Pai
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109-0600, USA
| | - Sara R. Rivera
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109-0600, USA
| | - Brian Carrick
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109-0600, USA
| | - David R. Engelke
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109-0600, USA
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21
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Golla U, Singh V, Azad GK, Singh P, Verma N, Mandal P, Chauhan S, Tomar RS. Sen1p contributes to genomic integrity by regulating expression of ribonucleotide reductase 1 (RNR1) in Saccharomyces cerevisiae. PLoS One 2013; 8:e64798. [PMID: 23741394 PMCID: PMC3669351 DOI: 10.1371/journal.pone.0064798] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 04/18/2013] [Indexed: 12/29/2022] Open
Abstract
Gene expression is a multi-step process which requires recruitment of several factors to promoters. One of the factors, Sen1p is an RNA/DNA helicase implicated in transcriptional termination and RNA processing in yeast. In the present study, we have identified a novel function of Sen1p that regulates the expression of ribonucleotide reductase RNR1 gene, which is essential for maintaining genomic integrity. Cells with mutation in the helicase domain or lacking N-terminal domain of Sen1p displayed a drastic decrease in the basal level transcription of RNR1 gene and showed enhanced sensitivity to various DNA damaging agents. Moreover, SEN1 mutants [Sen1-1 (G1747D), Sen1-2 (Δ1-975)] exhibited defects in DNA damage checkpoint activation. Surprisingly, CRT1 deletion in Sen1p mutants (Sen1-1, Sen1-2) was partly able to rescue the slow growth phenotype upon genotoxic stress. Altogether, our observations suggest that Sen1p is required for cell protection against DNA damage by regulating the expression of DNA repair gene RNR1. Thus, the misregulation of Sen1p regulated genes can cause genomic instability that may lead to neurological disorders and premature aging.
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Affiliation(s)
- Upendarrao Golla
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Vikash Singh
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Gajendra Kumar Azad
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Prabhat Singh
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Naveen Verma
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Papita Mandal
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Sakshi Chauhan
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Raghuvir S. Tomar
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
- * E-mail:
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22
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Marquina M, Queralt E, Casamayor A, Ariño J. Lack of the Glc7 phosphatase regulatory subunit Ypi1 activates the morphogenetic checkpoint. Int J Biochem Cell Biol 2012; 44:1862-71. [DOI: 10.1016/j.biocel.2012.06.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/15/2012] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
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23
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Heger CD, Wrann CD, Collins RN. Phosphorylation provides a negative mode of regulation for the yeast Rab GTPase Sec4p. PLoS One 2011; 6:e24332. [PMID: 21931684 PMCID: PMC3171412 DOI: 10.1371/journal.pone.0024332] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 08/06/2011] [Indexed: 12/31/2022] Open
Abstract
The Rab family of Ras-related GTPases are part of a complex signaling circuitry in eukaryotic cells, yet we understand little about the mechanisms that underlie Rab protein participation in such signal transduction networks, or how these networks are integrated at the physiological level. Reversible protein phosphorylation is widely used by cells as a signaling mechanism. Several phospho-Rabs have been identified, however the functional consequences of the modification appear to be diverse and need to be evaluated on an individual basis. In this study we demonstrate a role for phosphorylation as a negative regulatory event for the action of the yeast Rab GTPase Sec4p in regulating polarized growth. Our data suggest that the phosphorylation of the Rab Sec4p prevents interactions with its effector, the exocyst component Sec15p, and that the inhibition may be relieved by a PP2A phosphatase complex containing the regulatory subunit Cdc55p.
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Affiliation(s)
- Christopher D. Heger
- Graduate Program in Pharmacology, Cornell University, Ithaca, New York, United States of America
- Department of Molecular Medicine, Cornell University, Ithaca, New York, United States of America
| | - Christiane D. Wrann
- Leadership Program for Veterinary Students, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Ruth N. Collins
- Department of Molecular Medicine, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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24
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Slt2 and Rim101 contribute independently to the correct assembly of the chitin ring at the budding yeast neck in Saccharomyces cerevisiae. EUKARYOTIC CELL 2009; 8:1449-59. [PMID: 19633265 DOI: 10.1128/ec.00153-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Saccharomyces cerevisiae, the simultaneous absence of Slt2 and Rim101 prevents growth in nonosmotically stabilized media (F. Castrejon et al., Eukaryot. Cell 5:507-517, 2006). The double mutant slt2Delta rim101Delta displays altered chitin rings, together with a significant reduction in the overall levels of chitin. Cultures of this mutant lyse upon transfer to nonosmotically stabilized media, mostly through the bud, and such lysis is partially prevented by deletion of the chitinase gene (CTS1). Growth of the slt2Delta rim101Delta double mutant was restored by the overexpression of the GFA1 or CCT7 genes, which code for two biologically unrelated proteins. Further characterization of the mutant and its suppressors indicated that both Slt2 and Rim101 were independently required for the correct assembly of the septum machinery and that their concomitant absence reduced Chs3 accumulation at the neck, leading to lower levels of chitin. GFA1 overexpression, as well as the addition of glucosamine to the growth medium, specifically suppressed the growth defects by activating chitin synthesis at the neck and restoring the normal assembly of the chitin ring. In contrast, overexpression of CCT7, a Cct chaperonin subunit, alleviated the defect in the septum machinery without affecting chitin synthesis. Both suppressors thus act by reducing neck fragility through different mechanisms and allow growth in nonstabilized media. This work reports new roles for Slt2 and Rim101 in septum formation in budding yeast and confirms the homeostatic role of the chitin ring in the maintenance of neck integrity during cell division.
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25
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Pinsky BA, Nelson CR, Biggins S. Protein phosphatase 1 regulates exit from the spindle checkpoint in budding yeast. Curr Biol 2009; 19:1182-7. [PMID: 19592248 DOI: 10.1016/j.cub.2009.06.043] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 05/26/2009] [Accepted: 06/18/2009] [Indexed: 10/20/2022]
Abstract
Accurate chromosome segregation depends on sister kinetochores coming under tension when they make bioriented attachments to microtubules from opposite poles. The spindle checkpoint halts the cell cycle in response to defects in generating proper attachments or tension on kinetochores, although the precise signal that triggers the checkpoint is unclear because tension and attachment are coupled. The target of the checkpoint is the Cdc20 protein, which initiates the anaphase-promoting complex (APC)-dependent degradation of the anaphase inhibitor Pds1/securin. Although the molecular details of spindle checkpoint activation are still being elucidated, phosphorylation by at least four kinases is a crucial requirement. However, less is known about the mechanisms that silence the checkpoint after kinetochores biorient. Here, we show that the catalytic subunit of the budding yeast protein phosphatase 1 (PP1) homolog, Glc7, regulates exit from the checkpoint. Glc7 overexpression prevents spindle checkpoint activation in response to both tension and attachment defects. Although glc7 mutant cells are able to efficiently release from a non-checkpoint-mediated metaphase arrest, they are uniquely sensitive to transient spindle checkpoint activation as a result of a failure in spindle checkpoint exit. We therefore propose that PP1 activity silences the checkpoint by reversing key phosphorylation events.
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Affiliation(s)
- Benjamin A Pinsky
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, PO Box 19024, Seattle, WA 98109, USA
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Logan MR, Nguyen T, Szapiel N, Knockleby J, Por H, Zadworny M, Neszt M, Harrison P, Bussey H, Mandato CA, Vogel J, Lesage G. Genetic interaction network of the Saccharomyces cerevisiae type 1 phosphatase Glc7. BMC Genomics 2008; 9:336. [PMID: 18627629 PMCID: PMC2481269 DOI: 10.1186/1471-2164-9-336] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Accepted: 07/15/2008] [Indexed: 01/21/2023] Open
Abstract
Background Protein kinases and phosphatases regulate protein phosphorylation, a critical means of modulating protein function, stability and localization. The identification of functional networks for protein phosphatases has been slow due to their redundant nature and the lack of large-scale analyses. We hypothesized that a genome-scale analysis of genetic interactions using the Synthetic Genetic Array could reveal protein phosphatase functional networks. We apply this approach to the conserved type 1 protein phosphatase Glc7, which regulates numerous cellular processes in budding yeast. Results We created a novel glc7 catalytic mutant (glc7-E101Q). Phenotypic analysis indicates that this novel allele exhibits slow growth and defects in glucose metabolism but normal cell cycle progression and chromosome segregation. This suggests that glc7-E101Q is a hypomorphic glc7 mutant. Synthetic Genetic Array analysis of glc7-E101Q revealed a broad network of 245 synthetic sick/lethal interactions reflecting that many processes are required when Glc7 function is compromised such as histone modification, chromosome segregation and cytokinesis, nutrient sensing and DNA damage. In addition, mitochondrial activity and inheritance and lipid metabolism were identified as new processes involved in buffering Glc7 function. An interaction network among 95 genes genetically interacting with GLC7 was constructed by integration of genetic and physical interaction data. The obtained network has a modular architecture, and the interconnection among the modules reflects the cooperation of the processes buffering Glc7 function. Conclusion We found 245 genes required for the normal growth of the glc7-E101Q mutant. Functional grouping of these genes and analysis of their physical and genetic interaction patterns bring new information on Glc7-regulated processes.
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Affiliation(s)
- Michael R Logan
- Department of Biology, McGill University, Montreal (QC), Canada.
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Hoon S, Smith AM, Wallace IM, Suresh S, Miranda M, Fung E, Proctor M, Shokat KM, Zhang C, Davis RW, Giaever G, St Onge RP, StOnge RP, Nislow C. An integrated platform of genomic assays reveals small-molecule bioactivities. Nat Chem Biol 2008; 4:498-506. [PMID: 18622389 DOI: 10.1038/nchembio.100] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 06/16/2008] [Indexed: 01/27/2023]
Abstract
Bioactive compounds are widely used to modulate protein function and can serve as important leads for drug development. Identifying the in vivo targets of these compounds remains a challenge. Using yeast, we integrated three genome-wide gene-dosage assays to measure the effect of small molecules in vivo. A single TAG microarray was used to resolve the fitness of strains derived from pools of (i) homozygous deletion mutants, (ii) heterozygous deletion mutants and (iii) genomic library transformants. We demonstrated, with eight diverse reference compounds, that integration of these three chemogenomic profiles improves the sensitivity and specificity of small-molecule target identification. We further dissected the mechanism of action of two protein phosphatase inhibitors and in the process developed a framework for the rational design of multidrug combinations to sensitize cells with specific genotypes more effectively. Finally, we applied this platform to 188 novel synthetic chemical compounds and identified both potential targets and structure-activity relationships.
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Affiliation(s)
- Shawn Hoon
- Department of Genetics, Stanford University, Mail Stop-5120, Palo Alto, California 94305, USA
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Bär C, Zabel R, Liu S, Stark MJR, Schaffrath R. A versatile partner of eukaryotic protein complexes that is involved in multiple biological processes: Kti11/Dph3. Mol Microbiol 2008; 69:1221-33. [PMID: 18627462 DOI: 10.1111/j.1365-2958.2008.06350.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The Kluyveromyces lactis killer toxin zymocin insensitive 11 (KTI11) gene from Saccharomyces cerevisiae is allelic with the diphthamide synthesis 3 (DPH3) locus. Here, we present evidence that the KTI11 gene product is a versatile partner of proteins and operates in multiple biological processes. Notably, Kti11 immune precipitates contain Elp2 and Elp5, two subunits of the Elongator complex which is involved in transcription, tRNA modification and zymocin toxicity. KTI11 deletion phenocopies Elongator-minus cells and causes antisuppression of nonsense and missense suppressor tRNAs (SUP4, SOE1), zymocin resistance and protection against the tRNase attack of zymocin. In addition and unlike Elongator mutants, kti11 mutants resist diphtheria toxin (DT), protect against ADP-ribosylation of eukaryotic translation elongation factor 2 (eEF2) by DT and induce resistance against sordarin, an eEF2 poisoning antifungal. The latter phenotype applies to all diphthamide mutants (dph1-dph5) tested and Kti11/Dph3 physically interacts with diphthamide synthesis factors Dph1 and Dph2, presumably as part of a trimeric complex. Moreover, we present a separation of function mutation in KTI11, kti11-1, which dissociates zymocin resistance from DT sensitivity. It encodes a C-terminal Kti11 truncation that almost entirely abolishes Elongator interaction without affecting association with Kti13, another Kti11 partner protein.
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Affiliation(s)
- Christian Bär
- Biologicum, Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
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Zabel R, Bär C, Mehlgarten C, Schaffrath R. Yeast alpha-tubulin suppressor Ats1/Kti13 relates to the Elongator complex and interacts with Elongator partner protein Kti11. Mol Microbiol 2008; 69:175-87. [PMID: 18466297 DOI: 10.1111/j.1365-2958.2008.06273.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The alpha-tubulin suppressor 1 (ATS1) gene and the killer toxin-insensitive 13 (KTI13) locus from Saccharomyces cerevisiae are allelic. The Ats1/Kti13 gene product interacts with the cell polarity factor Nap1 and promotes growth inhibition of S. cerevisiae by zymocin, a tRNAse toxin complex from Kluyveromyces lactis. Kti13 removal causes zymocin resistance, a trait that is typical of defects in the Elongator complex. Here, we show that Kti13 co-purifies with the Elongator partner protein Kti11 and that the Kti11 interaction, not the Nap1 partnership, requires the C-terminus of Kti13. Moreover, Kti13 functionally relates to roles of the Elongator complex in tRNA wobble uridine modification, tRNA suppression of nonsense (SUP4) and missense (SOE1) mutations and tRNA restriction by zymocin. Also, inactivation of Kti13 or Elongator rescues the thermosensitive growth defect of secretory mutants (sec2-59(ts), sec12-4(ts)), suggesting that Kti13 and Elongator affect secretion processes that depend on the GTP exchange factors Sec2 and Sec12 respectively. Distinct from tandem deletions in KTI13 and Elongator genes, a kti13Delta kti11Delta double deletion induces synthetic sickness or lethality. In sum, our data suggest that Kti13 and Kti11 support Elongator functions and that they both share Elongator-independent role(s) that are important for cell viability.
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Affiliation(s)
- René Zabel
- Biologicum, Institut für Biologie, Institutsbereich Genetik, Martin-Luther-Universität, Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
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Pal G, Paraz MTZ, Kellogg DR. Regulation of Mih1/Cdc25 by protein phosphatase 2A and casein kinase 1. ACTA ACUST UNITED AC 2008; 180:931-45. [PMID: 18316413 PMCID: PMC2265403 DOI: 10.1083/jcb.200711014] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The Cdc25 phosphatase promotes entry into mitosis by removing cyclin-dependent kinase 1 (Cdk1) inhibitory phosphorylation. Previous work suggested that Cdc25 is activated by Cdk1 in a positive feedback loop promoting entry into mitosis; however, it has remained unclear how the feedback loop is initiated. To learn more about the mechanisms that regulate entry into mitosis, we have characterized the function and regulation of Mih1, the budding yeast homologue of Cdc25. We found that Mih1 is hyperphosphorylated early in the cell cycle and is dephosphorylated as cells enter mitosis. Casein kinase 1 is responsible for most of the hyperphosphorylation of Mih1, whereas protein phosphatase 2A associated with Cdc55 dephosphorylates Mih1. Cdk1 appears to directly phosphorylate Mih1 and is required for initiation of Mih1 dephosphorylation as cells enter mitosis. Collectively, these observations suggest that Mih1 regulation is achieved by a balance of opposing kinase and phosphatase activities. Because casein kinase 1 is associated with sites of polar growth, it may regulate Mih1 as part of a signaling mechanism that links successful completion of growth-related events to cell cycle progression.
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Affiliation(s)
- Gayatri Pal
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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Bharucha JP, Larson JR, Gao L, Daves LK, Tatchell K. Ypi1, a positive regulator of nuclear protein phosphatase type 1 activity in Saccharomyces cerevisiae. Mol Biol Cell 2008; 19:1032-45. [PMID: 18172024 DOI: 10.1091/mbc.e07-05-0499] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The catalytic subunit of protein phosphatase type 1 (PP1) has an essential role in mitosis, acting in opposition to the Ipl1/Aurora B protein kinase to ensure proper kinetochore-microtubule interactions. However, the regulatory subunit(s) that completes the PP1 holoenzyme that functions in this capacity is not known. We show here that the budding yeast Ypi1 protein is a nuclear protein that functions with PP1 (Glc7) in this mitotic role. Depletion of cellular Ypi1 induces mitotic arrest due to activation of the spindle checkpoint. Ypi1 depletion is accompanied by a reduction of nuclear PP1 and by loss of nuclear Sds22, a Glc7 binding partner that is found in a ternary complex with Ypi1 and Glc7. Expression of a Ypi1 variant that binds weakly to PP1 also activates the spindle checkpoint and suppresses the temperature sensitivity of an ipl1-2 mutant. These results, together with genetic interactions among YPI1, GLC7, and SDS22 mutants, indicate that Ypi1 and Sds22 are positive regulators of the nuclear Glc7 activity that is required for mitosis.
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Affiliation(s)
- Jennifer P Bharucha
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
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32
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Gibbons JA, Kozubowski L, Tatchell K, Shenolikar S. Expression of Human Protein Phosphatase-1 in Saccharomyces cerevisiae Highlights the Role of Phosphatase Isoforms in Regulating Eukaryotic Functions. J Biol Chem 2007; 282:21838-47. [PMID: 17545157 DOI: 10.1074/jbc.m701272200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human (PP1) isoforms, PP1alpha, PP1beta, PP1gamma1, and PP1gamma2, differ in primary sequences at N and C termini that potentially bind cellular regulators and define their physiological functions. The GLC7 gene encodes the PP1 catalytic subunit with >80% sequence identity to human PP1 and is essential for viability of Saccharomyces cerevisiae. In yeast, Glc7p regulates glycogen and protein synthesis, actin cytoskeleton, gene expression, and cell division. We substituted human PP1 for Glc7p in yeast to investigate the ability of individual isoforms to catalyze Glc7p functions. S. cerevisiae expressing human PP1 isoforms were viable. PP1alpha-expressing yeast grew more rapidly than strains expressing other isoforms. On the other hand, PP1alpha-expressing yeast accumulated less glycogen than PP1beta-or PP1gamma1-expressing yeast. Yeast expressing human PP1 were indistinguishable from WT yeast in glucose derepression. However, unlike WT yeast, strains expressing human PP1 failed to sporulate. Analysis of chimeric PP1alpha/beta subunits highlighted a critical role for their unique N termini in defining PP1alpha and PP1beta functions in yeast. Biochemical studies established that the differing association of PP1 isoforms with the yeast glycogen-targeting subunit, Gac1p, accounted for their differences in glycogen synthesis. In contrast to human PP1 expressed in Escherichia coli, enzymes expressed in yeast displayed in vitro biochemical properties closely resembling PP1 from mammalian tissues. Thus, PP1 expression in yeast should facilitate future structure-function studies of this protein serine/threonine phosphatase.
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Affiliation(s)
- Jennifer A Gibbons
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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33
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Toshima J, Toshima JY, Duncan MC, Cope MJT, Sun Y, Martin AC, Anderson S, Yates JR, Mizuno K, Drubin DG. Negative regulation of yeast Eps15-like Arp2/3 complex activator, Pan1p, by the Hip1R-related protein, Sla2p, during endocytosis. Mol Biol Cell 2006; 18:658-68. [PMID: 17151356 PMCID: PMC1783767 DOI: 10.1091/mbc.e06-09-0788] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Control of actin assembly nucleated by the Arp2/3 complex plays a crucial role during budding yeast endocytosis. The yeast Eps15-related Arp2/3 complex activator, Pan1p, is essential for endocytic internalization and proper actin organization. Pan1p activity is negatively regulated by Prk1 kinase phosphorylation after endocytic internalization. Phosphorylated Pan1p is probably then dephosphorylated in the cytosol. Pan1p is recruited to endocytic sites approximately 25 s before initiation of actin polymerization, suggesting that its Arp2/3 complex activation activity is kept inactive during early stages of endocytosis by a yet-to-be-identified mechanism. However, how Pan1p is maintained in an inactive state is not clear. Using tandem affinity purification-tagged Pan1p, we identified End3p as a stoichiometric component of the Pan1p complex, and Sla2p, a yeast Hip1R-related protein, as a novel binding partner of Pan1p. Interestingly, Sla2p specifically inhibited Pan1p Arp2/3 complex activation activity in vitro. The coiled-coil region of Sla2p was important for Pan1p inhibition, and a pan1 partial loss-of-function mutant suppressed the temperature sensitivity, endocytic phenotypes, and actin phenotypes observed in sla2DeltaCC mutant cells that lack the coiled-coil region. Overall, our results establish that Sla2p's regulation of Pan1p plays an important role in controlling Pan1p-stimulated actin polymerization during endocytosis.
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Affiliation(s)
- Jiro Toshima
- *Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Junko Y. Toshima
- *Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Mara C. Duncan
- *Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202
| | - M. Jamie T.V. Cope
- *Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202
| | - Yidi Sun
- *Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202
| | - Adam C. Martin
- *Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202
| | - Scott Anderson
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037; and
| | - John R. Yates
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037; and
| | - Kensaku Mizuno
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - David G. Drubin
- *Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202
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Lottersberger F, Panza A, Lucchini G, Piatti S, Longhese MP. The Saccharomyces cerevisiae 14-3-3 proteins are required for the G1/S transition, actin cytoskeleton organization and cell wall integrity. Genetics 2006; 173:661-75. [PMID: 16648583 PMCID: PMC1526496 DOI: 10.1534/genetics.106.058172] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
14-3-3 proteins are highly conserved polypeptides that participate in many biological processes by binding phosphorylated target proteins. The Saccharomyces cerevisiae BMH1 and BMH2 genes, whose concomitant deletion is lethal, encode two functionally redundant 14-3-3 isoforms. To gain insights into the essential function(s) shared by these proteins, we searched for high-dosage suppressors of the growth defects of temperature-sensitive bmh mutants. Both the protein kinase C1 (Pkc1) and its upstream regulators Wsc2 and Mid2 were found to act as high dosage suppressors of bmh mutants' temperature sensitivity, indicating a functional interaction between 14-3-3 and Pkc1. Consistent with a role of 14-3-3 proteins in Pkc1-dependent cellular processes, shift to the restrictive temperature of bmh mutants severely impaired initiation of DNA replication, polarization of the actin cytoskeleton, and budding, as well as cell wall integrity. Because Pkc1 acts in concert with the Swi4-Swi6 (SBF) transcriptional activator to control all these processes, the defective G(1)/S transition of bmh mutants might be linked to impaired SBF activity. Indeed, the levels of the G(1) cyclin CLN2 transcripts, which are positively regulated by SBF, were dramatically reduced in bmh mutants. Remarkably, budding and DNA replication defects of bmh mutants were suppressed by CLN2 expression from an SBF-independent promoter, suggesting that 14-3-3 proteins might contribute to regulating the late G(1) transcriptional program.
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Affiliation(s)
- Francisca Lottersberger
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy
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35
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Pinsky BA, Kotwaliwale CV, Tatsutani SY, Breed CA, Biggins S. Glc7/protein phosphatase 1 regulatory subunits can oppose the Ipl1/aurora protein kinase by redistributing Glc7. Mol Cell Biol 2006; 26:2648-60. [PMID: 16537909 PMCID: PMC1430313 DOI: 10.1128/mcb.26.7.2648-2660.2006] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Faithful chromosome segregation depends on the opposing activities of the budding yeast Glc7/PP1 protein phosphatase and Ipl1/Aurora protein kinase. We explored the relationship between Glc7 and Ipl1 and found that the phosphorylation of the Ipl1 substrate, Dam1, was altered by decreased Glc7 activity, whereas Ipl1 levels, localization, and kinase activity were not. These data strongly suggest that Glc7 ensures accurate chromosome segregation by dephosphorylating Ipl1 targets rather than regulating the Ipl1 kinase. To identify potential Glc7 and Ipl1 substrates, we isolated ipl1-321 dosage suppressors. Seven genes (SDS22, BUD14, GIP3, GIP4, SOL1, SOL2, and PEX31) encode newly identified ipl1 dosage suppressors, and all 10 suppressors encode proteins that physically interact with Glc7. The overexpression of the Gip3 and Gip4 suppressors altered Glc7 localization, indicating they are previously unidentified Glc7 regulatory subunits. In addition, the overexpression of Gip3 and Gip4 from the galactose promoter restored Dam1 phosphorylation in ipl1-321 mutant cells and caused wild-type cells to arrest in metaphase with unsegregated chromosomes, suggesting that Gip3 and Gip4 overexpression impairs Glc7's mitotic functions. We therefore propose that the overexpression of Glc7 regulatory subunits can titrate Glc7 away from relevant Ipl1 targets and thereby suppress ipl1-321 cells by restoring the balance of phosphatase/kinase activity.
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Affiliation(s)
- Benjamin A Pinsky
- Molecular and Cellular Biology Program, University of Washington, Seattle 98195, USA
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36
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Abstract
Eukaryotic cells possess an exquisitely interwoven and fine-tuned series of signal transduction mechanisms with which to sense and respond to the ubiquitous fermentable carbon source glucose. The budding yeast Saccharomyces cerevisiae has proven to be a fertile model system with which to identify glucose signaling factors, determine the relevant functional and physical interrelationships, and characterize the corresponding metabolic, transcriptomic, and proteomic readouts. The early events in glucose signaling appear to require both extracellular sensing by transmembrane proteins and intracellular sensing by G proteins. Intermediate steps involve cAMP-dependent stimulation of protein kinase A (PKA) as well as one or more redundant PKA-independent pathways. The final steps are mediated by a relatively small collection of transcriptional regulators that collaborate closely to maximize the cellular rates of energy generation and growth. Understanding the nuclear events in this process may necessitate the further elaboration of a new model for eukaryotic gene regulation, called "reverse recruitment." An essential feature of this idea is that fine-structure mapping of nuclear architecture will be required to understand the reception of regulatory signals that emanate from the plasma membrane and cytoplasm. Completion of this task should result in a much improved understanding of eukaryotic growth, differentiation, and carcinogenesis.
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Affiliation(s)
- George M Santangelo
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406-5018, USA.
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Chang JS, Henry K, Geli MI, Lemmon SK. Cortical recruitment and nuclear-cytoplasmic shuttling of Scd5p, a protein phosphatase-1-targeting protein involved in actin organization and endocytosis. Mol Biol Cell 2006; 17:251-62. [PMID: 16251346 PMCID: PMC1345663 DOI: 10.1091/mbc.e05-10-0936] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Accepted: 10/17/2005] [Indexed: 11/11/2022] Open
Abstract
Scd5p regulates endocytosis and cortical actin organization as a targeting subunit for the Ser/Thr protein phosphatase-1 (PP1) in yeast. To identify localization signals in Scd5p required for cell surface recruitment, visualization of GFP-tagged Scd5 truncations and deletions was performed. Scd5p contains a PP1 binding site, a 3-repeat region of 20 amino acids (3R), and a 9-repeat region of 12 amino acids (9R). We found that the 9R is critical for cortical localization of Scd5p, but cortical recruitment is not essential for Scd5p's function in actin organization and endocytosis. We propose that Scd5p can target PP1 to endocytic factors in the cytoplasm that have been disassembled and/or inactivated by phosphorylation. We also found that Scd5p undergoes nuclear-cytoplasmic shuttling in a Crm1p-dependent manner. Scd5p-DeltaCT lacking the 9R region and its nuclear export signal (NES) accumulates in the nucleus, causing cortical actin and endocytic defects. Cytoplasmic localization and function of Scd5p-DeltaCT is restored by NES addition. However, removal of Scd5p's nuclear localization signal prevents nuclear entry, but endocytosis and actin organization remain relatively normal. These results indicate that nuclear-cytoplasmic shuttling is not required for regulation of Scd5p's cortical function and suggest that Scd5p has an independent nuclear function.
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Affiliation(s)
- Ji Suk Chang
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106-4960, USA
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38
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Zanelli CF, Valentini SR. Pkc1 acts through Zds1 and Gic1 to suppress growth and cell polarity defects of a yeast eIF5A mutant. Genetics 2005; 171:1571-81. [PMID: 16157662 PMCID: PMC1456085 DOI: 10.1534/genetics.105.048082] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 08/30/2005] [Indexed: 11/18/2022] Open
Abstract
eIF5A is a highly conserved putative eukaryotic translation initiation factor that has been implicated in translation initiation, nucleocytoplasmic transport, mRNA decay, and cell proliferation, but with no precise function assigned so far. We have previously shown that high-copy PKC1 suppresses the phenotype of tif51A-1, a temperature-sensitive mutant of eIF5A in S. cerevisiae. Here, in an attempt to further understand how Pkc1 functionally interacts with eIF-5A, it was determined that PKC1 suppression of tif51A-1 is independent of the cell integrity MAP kinase cascade. Furthermore, two new suppressor genes, ZDS1 and GIC1, were identified. We demonstrated that ZDS1 and ZDS2 are necessary for PKC1, but not for GIC1 suppression. Moreover, high-copy GIC1 also suppresses the growth defect of a PKC1 mutant (stt1), suggesting the existence of a Pkc1-Zds1-Gic1 pathway. Consistent with the function of Gic1 in actin organization, the tif51A-1 strain shows an actin polarity defect that is partially recovered by overexpression of Pkc1 and Zds1 as well as Gic1. Additionally, PCL1 and BNI1, important regulators of yeast cell polarity, also suppress tif51A-1 temperature sensitivity. Taken together, these data strongly support the correlated involvement of Pkc1 and eIF5A in establishing actin polarity, which is essential for bud formation and G1/S transition in S. cerevisiae.
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Affiliation(s)
- Cleslei F Zanelli
- Department of Biological Sciences, School of Pharmaceutical Sciences, São Paulo State University, UNESP, Rodovia Araraquara-Jaú, Km. 01, Araraquara, São Paulo 14801-902, Brazil
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De Wever V, Reiter W, Ballarini A, Ammerer G, Brocard C. A dual role for PP1 in shaping the Msn2-dependent transcriptional response to glucose starvation. EMBO J 2005; 24:4115-23. [PMID: 16281053 PMCID: PMC1356311 DOI: 10.1038/sj.emboj.7600871] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Accepted: 10/19/2005] [Indexed: 01/21/2023] Open
Abstract
In yeast, glucose depletion elicits a quick response in the transcription of stress-related genes. The main transcriptional activator that orchestrates this response is Msn2, whose nuclear localization and DNA binding are negatively controlled by the cAMP-dependent protein kinase (PKA). Msn2 activation by sudden glucose depletion correlates with a fast but transient decrease in phosphorylation of several sites in its nuclear localization signal (NLS). Here we show that protein phosphatase 1 (PP1) is the direct antagonist of PKA-dependent phosphorylation at the Msn2 nuclear import domain and therefore a potential mediator of glucose starvation signals that target this transcription factor. Apart from PKA, the protein kinase Snf1 can also directly modify one of the Msn2 phosphorylation sites (S582) and thereby repress Msn2 function. Consequently, in snf1 mutants, rephosphorylation of the NLS happens to be much slower during prolonged starvation. Thus, a second, Reg1-dependent form of PP1 indirectly influences Msn2 functionality by modulating Snf1 kinase activation and repression. Different activities of PP1 are therefore involved in shaping induction and adaptation of the transcriptional stress response during acute glucose starvation.
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Affiliation(s)
- Veerle De Wever
- Max F Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Biochemistry, University of Vienna and Ludwig Boltzmann-Forschungsstelle für Biochemie, Vienna, Austria
| | - Wolfgang Reiter
- Max F Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Biochemistry, University of Vienna and Ludwig Boltzmann-Forschungsstelle für Biochemie, Vienna, Austria
| | - Annalisa Ballarini
- Max F Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Biochemistry, University of Vienna and Ludwig Boltzmann-Forschungsstelle für Biochemie, Vienna, Austria
| | - Gustav Ammerer
- Max F Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Biochemistry, University of Vienna and Ludwig Boltzmann-Forschungsstelle für Biochemie, Vienna, Austria
| | - Cécile Brocard
- Max F Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Biochemistry, University of Vienna and Ludwig Boltzmann-Forschungsstelle für Biochemie, Vienna, Austria
- Max F Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Biochemistry, Vienna Biocenter, University of Vienna and Ludwig Boltzmann-Forschungsstelle für Biochemie, Dr Bohrgasse 9, 1030 Vienna, Austria. Tel.: +43 1 42 77 52 817; Fax: +43 1 42 77 9 528; E-mail:
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Ho HL, Shiau YS, Chen MY. Saccharomyces cerevisiaeTSC11/AVO3 participates in regulating cell integrity and functionally interacts with components of the Tor2 complex. Curr Genet 2005; 47:273-88. [PMID: 15809876 DOI: 10.1007/s00294-005-0570-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Revised: 02/10/2005] [Accepted: 02/20/2005] [Indexed: 12/22/2022]
Abstract
Saccharomyces cerevisiae TSC11/AVO3 is an essential gene encoding one component of TORC2, a multi-protein complex of yeast Tor2p that also contains Lst8p, Avo1p, and Avo2p. Despite the proven physical association among TORC2 components, little is known about the functional linkage or cellular pathways these proteins act in. Here, we present genetic data linking the function of TSC11 to the regulation of cell integrity. Mutants carrying temperature-sensitive (ts) alleles in different regions of TSC11 displayed cell wall defects, evidenced by characteristic osmotic stabilizer-remediable cell lysis, susceptibility to trypan blue staining, and sensitivity to cell wall-digesting enzymes. Dosage suppression analysis identified different groups of genes in rescuing phenotypes of different tsc11(ts) mutants. AVO1 suppressed one class of mutants, whereas active PKC1, AVO2, and SLM1 partially rescued another. Our findings demonstrate functional connections among TORC2 components and we speculate that Tsc11p exerts its function via a Pkc1p-independent mechanism mediated through Avo1p, and a Pkc1p-dependent mechanism mediated through Avo2p and Slm1p.
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Affiliation(s)
- Hsiang-Ling Ho
- Institute of Biochemistry, School of Life Sciences and Department of Biochemistry, School of Medicine, National Yang-Ming University, 155, Sec. 2, Li-Nong St., Shih-Pai, Taipei, 112, Taiwan
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41
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Vilella F, Herrero E, Torres J, de la Torre-Ruiz MA. Pkc1 and the upstream elements of the cell integrity pathway in Saccharomyces cerevisiae, Rom2 and Mtl1, are required for cellular responses to oxidative stress. J Biol Chem 2005; 280:9149-59. [PMID: 15637049 DOI: 10.1074/jbc.m411062200] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study we analyze the participation of the PKC1-MAPK cell integrity pathway in cellular responses to oxidative stress in Saccharomyces cerevisiae. Evidence is presented demonstrating that only Pkc1 and the upstream elements of the cell integrity pathway are essential for cell survival upon treatment with two oxidizing agents, diamide and hydrogen peroxide. Mtl1 is characterized for the first time as a cell-wall sensor of oxidative stress. We also show that the actin cytoskeleton is a cellular target for oxidative stress. Both diamide and hydrogen peroxide provoke a marked depolarization of the actin cytoskeleton, being Mtl1, Rom2 and Pkc1 functions all required to restore the correct actin organization. Diamide induces the formation of disulfide bonds in newly secreted cell-wall proteins. This mainly provokes structural changes in the cell outer layer, which activate the PKC1-MAPK pathway and hence the protein kinase Slt2. Our results led us to the conclusion that Pkc1 activity is required to overcome the effects of oxidative stress by: (i) enhancing the machinery required to repair the altered cell wall and (ii) restoring actin cytoskeleton polarity by promoting actin cable formation.
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Affiliation(s)
- Felipe Vilella
- Departament de Ciències Mèdiques Bàsiques, Alcalde Rovira Roure 44, Universitat de Lleida, Lleida 25198, Spain
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42
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Gilbert W, Guthrie C. The Glc7p nuclear phosphatase promotes mRNA export by facilitating association of Mex67p with mRNA. Mol Cell 2004; 13:201-12. [PMID: 14759366 DOI: 10.1016/s1097-2765(04)00030-9] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Revised: 11/24/2003] [Accepted: 12/01/2003] [Indexed: 11/17/2022]
Abstract
mRNA export is mediated by Mex67p:Mtr2p/NXF1:p15, a conserved heterodimeric export receptor that is thought to bind mRNAs through the RNA binding adaptor protein Yra1p/REF. Recently, mammalian SR (serine/arginine-rich) proteins were shown to act as alternative adaptors for NXF1-dependent mRNA export. Npl3p is an SR-like protein required for mRNA export in S. cerevisiae. Like mammalian SR proteins, Npl3p is serine-phosphorylated by a cytoplasmic kinase. Here we report that this phosphorylation of Npl3p is required for efficient mRNA export. We further show that the mRNA-associated fraction of Npl3p is unphosphorylated, implying a subsequent nuclear dephosphorylation event. We present evidence that the essential, nuclear phosphatase Glc7p promotes dephosphorylation of Npl3p in vivo and that nuclear dephosphorylation of Npl3p is required for mRNA export. Specifically, recruitment of Mex67p to mRNA is Glc7p dependent. We propose a model whereby a cycle of cytoplasmic phosphorylation and nuclear dephosphorylation of shuttling SR adaptor proteins regulates Mex67p:Mtr2p/NXF1:p15-dependent mRNA export.
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Affiliation(s)
- Wendy Gilbert
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, CA 94143, USA
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43
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Ceulemans H, Bollen M. Functional diversity of protein phosphatase-1, a cellular economizer and reset button. Physiol Rev 2004; 84:1-39. [PMID: 14715909 DOI: 10.1152/physrev.00013.2003] [Citation(s) in RCA: 490] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The protein serine/threonine phosphatase protein phosphatase-1 (PP1) is a ubiquitous eukaryotic enzyme that regulates a variety of cellular processes through the dephosphorylation of dozens of substrates. This multifunctionality of PP1 relies on its association with a host of function-specific targetting and substrate-specifying proteins. In this review we discuss how PP1 affects the biochemistry and physiology of eukaryotic cells. The picture of PP1 that emerges from this analysis is that of a "green" enzyme that promotes the rational use of energy, the recycling of protein factors, and a reversal of the cell to a basal and/or energy-conserving state. Thus PP1 promotes a shift to the more energy-efficient fuels when nutrients are abundant and stimulates the storage of energy in the form of glycogen. PP1 also enables the relaxation of actomyosin fibers, the return to basal patterns of protein synthesis, and the recycling of transcription and splicing factors. In addition, PP1 plays a key role in the recovery from stress but promotes apoptosis when cells are damaged beyond repair. Furthermore, PP1 downregulates ion pumps and transporters in various tissues and ion channels that are involved in the excitation of neurons. Finally, PP1 promotes the exit from mitosis and maintains cells in the G1 or G2 phases of the cell cycle.
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Affiliation(s)
- Hugo Ceulemans
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, Leuven, Belgium
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44
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García-Gimeno MA, Muñoz I, Ariño J, Sanz P. Molecular characterization of Ypi1, a novel Saccharomyces cerevisiae type 1 protein phosphatase inhibitor. J Biol Chem 2003; 278:47744-52. [PMID: 14506263 DOI: 10.1074/jbc.m306157200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Saccharomyces cerevisiae open reading frame YFR003c encodes a small (155-amino acid) hydrophilic protein that we identified as a novel, heat-stable inhibitor of type 1 protein phosphatase (Ypi1). Ypi1 interacts physically in vitro with both Glc7 and Ppz1 phosphatase catalytic subunits, as shown by pull-down assays. Ypi1 inhibits Glc7 but appears to be less effective toward Ppz1 phosphatase activity under the conditions tested. Ypi1 contains a 48RHNVRW53 sequence, which resembles the characteristic consensus PP1 phosphatase binding motif. A W53A mutation within this motif abolishes both binding to and inhibition of Glc7 and Ppz1 phosphatases. Deletion of YPI1 is lethal, suggesting a relevant role of the inhibitor in yeast physiology. Cells overexpressing Ypi1 display a number of phenotypes consistent with an inhibitory role of this protein on Glc7, such as decreased glycogen content and an increased growth defect in a slt2/mpk1 mitogen-activated protein kinase-deficient background. Taking together, these results define Ypi1 as the first inhibitory subunit of Glc7 identified in budding yeast.
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Affiliation(s)
- Maria Adelaida García-Gimeno
- Instituto de Biomedicina de Valencia Consejo Superior de Investigaciones Científicas, Jaime Roig 11, 46010-Valencia, Spain
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45
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Fichtner L, Jablonowski D, Schierhorn A, Kitamoto HK, Stark MJR, Schaffrath R. Elongator's toxin-target (TOT) function is nuclear localization sequence dependent and suppressed by post-translational modification. Mol Microbiol 2003; 49:1297-307. [PMID: 12940988 DOI: 10.1046/j.1365-2958.2003.03632.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The toxin target (TOT) function of the Saccharomyces cerevisiae Elongator complex enables Kluyveromyces lactis zymocin to induce a G1 cell cycle arrest. Loss of a ubiquitin-related system (URM1-UBA4 ) and KTI11 enhances post-translational modification/proteolysis of Elongator subunit Tot1p (Elp1p) and abrogates its TOT function. Using TAP tagging, Kti11p contacts Elongator and translational proteins (Rps7Ap, Rps19Ap Eft2p, Yil103wp, Dph2p). Loss of YIL103w and DPH2 (involved in diphtheria toxicity) suppresses zymocicity implying that both toxins overlap in a manner mediated by Kti11p. Among the pool that co-fractionates with RNA polymerase II (pol II) and nucleolin, Nop1p, unmodified Tot1p dominates. Thus, modification/proteolysis may affect association of Elongator with pol II or its localization. Consistently, an Elongator-nuclear localization sequence (NLS) targets green fluorescent protein (GFP) to the nucleus, and its truncation yields TOT deficiency. Similarly, KAP120 deletion rescues cells from zymocin, suggesting that Elongator's TOT function requires NLS- and karyopherin-dependent nuclear import.
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Affiliation(s)
- Lars Fichtner
- Biologicum, Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
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46
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Bar EE, Ellicott AT, Stone DE. Gbetagamma recruits Rho1 to the site of polarized growth during mating in budding yeast. J Biol Chem 2003; 278:21798-804. [PMID: 12660244 DOI: 10.1074/jbc.m212636200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In mating mixtures of Saccharomyces cerevisiae, cells polarize their growth toward their conjugation partners along a pheromone gradient. This chemotropic phenomenon is mediated by structural proteins such as Far1 and Bem1 and by signaling proteins such as Cdc24, Cdc42, and Gbetagamma. The Gbetagamma subunit is thought to provide a positional cue that recruits the polarity establishment proteins, and thereby induces polarization of the actin cytoskeleton. We identified RHO1 in a screen for allele-specific high-copy suppressors of Gbetagamma overexpression, suggesting that Rho1 binds Gbetagamma in vivo. Inactivation of Rho1 GTPase activity augmented the rescue phenotype, suggesting that it is the activated form of Rho1 that binds Gbetagamma. We also found, in a pull-down assay, that Rho1 associates with GST-Ste4 and that Rho1 is localized to the neck and tip of mating projections. Moreover, a mutation in STE4 that disrupts Gbetagamma-Rho1 interaction reduces the projection tip localization of Rho1 and compromises the integrity of pheromone-treated cells deficient in Rho1 activity. In addition to its roles as a positive regulator of 1,3-beta-glucan synthase and of the cell integrity MAP kinase cascade, it was recently shown that Rho1 is necessary for the formation of mating projections. Together, these results suggest that Gbetagamma recruits Rho1 to the site of polarized growth during mating.
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Affiliation(s)
- Eli E Bar
- Department of Biological Sciences, Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, IL 60607, USA
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Abstract
The human immunodeficiency virus protease (HIV-1 PR) was expressed both in the yeast Saccharomyces cerevisiae and in mammalian cells. Inducible expression of HIV-1 PR arrested yeast growth, which was followed by cell lysis. The lytic phenotype included loss of plasma membrane integrity and cell wall breakage leading to the release of cell content to the medium. Given that neither poliovirus 2A protease nor 2BC protein, both being highly toxic for S. cerevisiae, were able to produce similar effects, it seems that this lytic phenotype is specific of HIV-1 PR. Drastic alterations in membrane permeability preceded the lysis in yeast expressing HIV-1 PR. Cell killing and lysis provoked by HIV-1 PR were also observed in mammalian cells. Thus, COS7 cells expressing the protease showed increased plasma membrane permeability and underwent lysis by necrosis with no signs of apoptosis. Strikingly, the morphological alterations induced by HIV-1 PR in yeast and mammalian cells were similar in many aspects. To our knowledge, this is the first report of a viral protein with such an activity. These findings contribute to the present knowledge on HIV-1-induced cytopathogenesis.
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Affiliation(s)
- Raquel Blanco
- Centro de Biologia Molecular Severo Ochoa Consejo Superior Investigaciones Cientificas-Universidad Autónoma de Madrid, Spain
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48
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Zeke T, Kókai E, Szöor B, Yatzkan E, Yarden O, Szirák K, Fehér Z, Bagossi P, Gergely P, Dombrádi V. Expression of protein phosphatase 1 during the asexual development of Neurospora crassa. Comp Biochem Physiol B Biochem Mol Biol 2003; 134:161-70. [PMID: 12524044 DOI: 10.1016/s1096-4959(02)00188-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We cloned and sequenced the cDNA and the gene encoding the catalytic subunit of protein phosphatase 1 from the filamentous fungus Neurospora crassa. The gene, designated ppp-1 (phosphoprotein phosphatase 1), was mapped by restriction fragment length polymorphism to linkage group III, in the vicinity of con-7 and trp-1. The expression of the gene was monitored by reverse transcriptase and polymerase chain reactions, by Western blotting, and by protein phosphatase activity assays in synchronized cultures. Transcripts of ppp-1 were detected in the dormant conidia. The abundance of ppp-1 mRNA, Ppp-1 protein, and the activity of protein phosphatase 1 increased during germination and subsequent hyphal elongation as well as during the early stages of aerial mycelium formation.
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Affiliation(s)
- Tamás Zeke
- Department of Medical Chemistry, Medical and Health Sciences Center, University of Debrecen, H-4026 Debrecen, Hungary
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49
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Chang JS, Henry K, Wolf BL, Geli M, Lemmon SK. Protein phosphatase-1 binding to scd5p is important for regulation of actin organization and endocytosis in yeast. J Biol Chem 2002; 277:48002-8. [PMID: 12356757 DOI: 10.1074/jbc.m208471200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SCD5, an essential gene, encodes a protein important for endocytosis and actin organization in yeast. Previous two-hybrid screens showed that Scd5p interacts with Glc7p, a yeast Ser/Thr-specific protein phosphatase-1 (PP1) that participates in a variety of cellular processes. PP1 substrate specificity in vivo is regulated by association with different regulatory or targeting subunits, many of which have a consensus PP1-binding site ((V/I)XF, with a basic residue at the -1 or -2 position). Scd5p contains two of these potential PP1-binding motifs: KVDF (amino acids 240-243) and KKVRF (amino acids 272-276). Deletion analysis mapped the PP1-binding domain to a region of Scd5p containing these motifs. Therefore, the consequence of mutating these two potential PP1-binding sites was examined. Although mutation of KVDF had no effect, alteration of KKVRF dramatically reduced Scd5p interaction with Glc7p and resulted in temperature-sensitive growth. Furthermore, this mutation caused defects in fluid phase and receptor-mediated endocytosis and actin organization. Overexpression of GLC7 suppressed the temperature-sensitive growth of the KKVRF mutant and partially rescued the actin organization phenotype. These results provide evidence that Scd5p is a PP1 targeting subunit for regulation of actin organization and endocytosis or that Scd5p is a PP1 substrate, which regulates the function of Scd5p in these processes.
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Affiliation(s)
- Ji Suk Chang
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106-4960, USA
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50
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Cullen PJ, Sprague GF. The Glc7p-interacting protein Bud14p attenuates polarized growth, pheromone response, and filamentous growth in Saccharomyces cerevisiae. EUKARYOTIC CELL 2002; 1:884-94. [PMID: 12477789 PMCID: PMC138766 DOI: 10.1128/ec.1.6.884-894.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A genetic selection in Saccharomyces cerevisiae for mutants that stimulate the mating pathway uncovered a mutant that had a hyperactive pheromone response pathway and also had hyperpolarized growth. Cloning and segregation analysis demonstrated that BUD14 was the affected gene. Disruption of BUD14 in wild-type cells caused mild stimulation of pheromone response pathway reporters, an increase in sensitivity to mating factor, and a hyperelongated shmoo morphology. The bud14 mutant also had hyperfilamentous growth. Consistent with a role in the control of cell polarity, a Bud14p-green fluorescent protein fusion was localized to sites of polarized growth in the cell. Bud14p shared morphogenetic functions with the Ste20p and Bni1p proteins as well as with the type 1 phosphatase Glc7p. The genetic interactions between BUD14 and GLC7 suggested a role for Glc7p in filamentous growth, and Glc7p was found to have a positive function in filamentous growth in yeast.
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Affiliation(s)
- Paul J Cullen
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA
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