1
|
Amodeo S, Bregy I, Ochsenreiter T. Mitochondrial genome maintenance-the kinetoplast story. FEMS Microbiol Rev 2023; 47:fuac047. [PMID: 36449697 PMCID: PMC10719067 DOI: 10.1093/femsre/fuac047] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 08/13/2022] [Accepted: 11/24/2022] [Indexed: 12/17/2023] Open
Abstract
Mitochondrial DNA replication is an essential process in most eukaryotes. Similar to the diversity in mitochondrial genome size and organization in the different eukaryotic supergroups, there is considerable diversity in the replication process of the mitochondrial DNA. In this review, we summarize the current knowledge of mitochondrial DNA replication and the associated factors in trypanosomes with a focus on Trypanosoma brucei, and provide a new model of minicircle replication for this protozoan parasite. The model assumes the mitochondrial DNA (kinetoplast DNA, kDNA) of T. brucei to be loosely diploid in nature and the replication of the genome to occur at two replication centers at the opposing ends of the kDNA disc (also known as antipodal sites, APS). The new model is consistent with the localization of most replication factors and in contrast to the current model, it does not require the assumption of an unknown sorting and transport complex moving freshly replicated DNA to the APS. In combination with the previously proposed sexual stages of the parasite in the insect vector, the new model provides a mechanism for maintenance of the mitochondrial genetic diversity.
Collapse
Affiliation(s)
- Simona Amodeo
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Hochschulstrasse 6, 3012 Bern, Switzerland
| | - Irina Bregy
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Hochschulstrasse 6, 3012 Bern, Switzerland
| | - Torsten Ochsenreiter
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
| |
Collapse
|
2
|
Singh P, Samanta K, Kebe NM, Michel G, Legrand B, Sitnikova VE, Kajava AV, Pagès M, Bastien P, Pomares C, Coux O, Hernandez JF. The C-terminal segment of Leishmania major HslU: Toward potential inhibitors of LmHslVU activity. Bioorg Chem 2021; 119:105539. [PMID: 34894575 DOI: 10.1016/j.bioorg.2021.105539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/08/2021] [Accepted: 12/01/2021] [Indexed: 01/23/2023]
Abstract
It is urgent to develop less toxic and more efficient treatments for leishmaniases and trypanosomiases. We explore the possibility to target the parasite mitochondrial HslVU protease, which is essential for growth and has no analogue in the human host. For this, we develop compounds potentially inhibiting the complex assembly by mimicking the C-terminal (C-ter) segment of the ATPase HslU. We previously showed that a dodecapeptide derived from Leishmania major HslU C-ter segment (LmC12-U2, Cpd 1) was able to bind to and activate the digestion of a fluorogenic substrate by LmHslV. Here, we present the study of its structure-activity relationships. By replacing each essential residue with related non-proteinogenic residues, we obtained more potent analogues. In particular, a cyclohexylglycine residue at position 11 (cpd 24) allowed a more than three-fold gain in potency while reducing the size of compound 24 from twelve to six residues (cpd 50) without significant loss of potency, opening the way toward short HslU C-ter peptidomimetics as potential inhibitors of HslV proteolytic function. Finally, conjugates constituted of LmC6-U2 analogues and a mitochondrial penetrating peptide were found to penetrate into the promastigote form of L. infantum and to inhibit the parasite growth without showing toxicity toward human THP-1 cells at the same concentration (i.e. 30 μM).
Collapse
Affiliation(s)
- Priyanka Singh
- IBMM, CNRS, Univ Montpellier, ENSCM, Montpellier, France
| | | | - Ndeye Mathy Kebe
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), UMR5237, CNRS, Univ Montpellier, 1919, route de Mende, 34000 Montpellier, France
| | - Grégory Michel
- Centre Méditerranéen de Médecine Moléculaire (C3M), U1065, Université Côte d'Azur, Inserm, Archimed Building, 151 route Saint Antoine de Ginestière, 06000 Nice, France
| | | | - Vera E Sitnikova
- International Research Institute of Bioengineering, ITMO University, Kronverksky Pr. 49, 197101 Saint Petersburg, Russia
| | - Andrey V Kajava
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), UMR5237, CNRS, Univ Montpellier, 1919, route de Mende, 34000 Montpellier, France
| | - Michel Pagès
- MIVEGEC, Univ Montpellier, CNRS, IRD, CHU, 191 avenue du Doyen Giraud, 34000 Montpellier, France
| | - Patrick Bastien
- MIVEGEC, Univ Montpellier, CNRS, IRD, CHU, 191 avenue du Doyen Giraud, 34000 Montpellier, France
| | - Christelle Pomares
- Centre Méditerranéen de Médecine Moléculaire (C3M), U1065, Université Côte d'Azur, Inserm, Archimed Building, 151 route Saint Antoine de Ginestière, 06000 Nice, France
| | - Olivier Coux
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), UMR5237, CNRS, Univ Montpellier, 1919, route de Mende, 34000 Montpellier, France.
| | | |
Collapse
|
3
|
Trypanosoma brucei Tim50 Possesses PAP Activity and Plays a Critical Role in Cell Cycle Regulation and Parasite Infectivity. mBio 2021; 12:e0159221. [PMID: 34517757 PMCID: PMC8546626 DOI: 10.1128/mbio.01592-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Trypanosoma brucei, the infective agent for African trypanosomiasis, possesses a homologue of the translocase of the mitochondrial inner membrane 50 (TbTim50). It has a pair of characteristic phosphatase signature motifs, DXDX(T/V). Here, we demonstrated that, besides its protein phosphatase activity, the recombinant TbTim50 binds and hydrolyzes phosphatidic acid in a concentration-dependent manner. Mutations of D242 and D244, but not of D345and D347, to alanine abolished these activities. In silico structural homology models identified the putative binding interfaces that may accommodate different phosphosubstrates. Interestingly, TbTim50 depletion in the bloodstream form (BF) of T. brucei reduced cardiolipin (CL) levels and decreased mitochondrial membrane potential (ΔΨ). TbTim50 knockdown (KD) also reduced the population of G2/M phase and increased that of G1 phase cells; inhibited segregation and caused overreplication of kinetoplast DNA (kDNA), and reduced BF cell growth. Depletion of TbTim50 increased the levels of AMPK phosphorylation, and parasite morphology was changed with upregulation of expression of a few stumpy marker genes. Importantly, we observed that TbTim50-depleted parasites were unable to establish infection in mice. Proteomics analysis showed reductions in levels of the translation factors, flagellar transport proteins, and many proteasomal subunits, including those of the mitochondrial heat shock locus ATPase (HslVU), which is known to play a role in regulation of kinetoplast DNA (kDNA) replication. Reduction of the level of HslV in TbTim50 KD cells was further validated by immunoblot analysis. Together, our results showed that TbTim50 is essential for mitochondrial function, regulation of kDNA replication, and the cell cycle in the BF. Therefore, TbTim50 is an important target for structure-based drug design to combat African trypanosomiasis.
Collapse
|
4
|
Yaffe N, Rotem D, Soni A, Porath D, Shlomai J. Direct monitoring of the stepwise condensation of kinetoplast DNA networks. Sci Rep 2021; 11:1501. [PMID: 33452335 PMCID: PMC7810991 DOI: 10.1038/s41598-021-81045-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 01/04/2021] [Indexed: 11/09/2022] Open
Abstract
Condensation and remodeling of nuclear genomes play an essential role in the regulation of gene expression and replication. Yet, our understanding of these processes and their regulatory role in other DNA-containing organelles, has been limited. This study focuses on the packaging of kinetoplast DNA (kDNA), the mitochondrial genome of kinetoplastids. Severe tropical diseases, affecting large human populations and livestock, are caused by pathogenic species of this group of protists. kDNA consists of several thousand DNA minicircles and several dozen DNA maxicircles that are linked topologically into a remarkable DNA network, which is condensed into a mitochondrial nucleoid. In vitro analyses implicated the replication protein UMSBP in the decondensation of kDNA, which enables the initiation of kDNA replication. Here, we monitored the condensation of kDNA, using fluorescence and atomic force microscopy. Analysis of condensation intermediates revealed that kDNA condensation proceeds via sequential hierarchical steps, where multiple interconnected local condensation foci are generated and further assemble into higher order condensation centers, leading to complete condensation of the network. This process is also affected by the maxicircles component of kDNA. The structure of condensing kDNA intermediates sheds light on the structural organization of the condensed kDNA network within the mitochondrial nucleoid.
Collapse
Affiliation(s)
- Nurit Yaffe
- Department of Microbiology and Molecular Genetics, Institute of Medical Research Israel-Canada, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel
| | - Dvir Rotem
- Institute of Chemistry, The Center for Nanoscience and Nanotechnology, Edmond J. Safra Campus, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel
| | - Awakash Soni
- Department of Microbiology and Molecular Genetics, Institute of Medical Research Israel-Canada, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel
| | - Danny Porath
- Institute of Chemistry, The Center for Nanoscience and Nanotechnology, Edmond J. Safra Campus, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
| | - Joseph Shlomai
- Department of Microbiology and Molecular Genetics, Institute of Medical Research Israel-Canada, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel.
| |
Collapse
|
5
|
Update on relevant trypanosome peptidases: Validated targets and future challenges. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140577. [PMID: 33271348 DOI: 10.1016/j.bbapap.2020.140577] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/09/2020] [Accepted: 11/24/2020] [Indexed: 02/06/2023]
Abstract
Trypanosoma cruzi, the agent of the American Trypanosomiasis, Chagas disease, and Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, the agents of Sleeping sickness (Human African Trypanosomiasis, HAT), as well as Trypanosoma brucei brucei, the agent of the cattle disease nagana, contain cysteine, serine, threonine, aspartyl and metallo peptidases. The most abundant among these enzymes are the cysteine proteases from the Clan CA, the Cathepsin L-like cruzipain and rhodesain, and the Cathepsin B-like enzymes, which have essential roles in the parasites and thus are potential targets for chemotherapy. In addition, several other proteases, present in one or both parasites, have been characterized, and some of them are also promising candidates for the developing of new drugs. Recently, new inhibitors, with good selectivity for the parasite proteasomes, have been described and are very promising as lead compounds for the development of new therapies for these neglected diseases. This article is part of a Special Issue entitled: "Play and interplay of proteases in health and disease".
Collapse
|
6
|
Kovalinka T, Pánek T, Kováčová B, Horváth A. Orientation of FtsH protease homologs in Trypanosoma brucei inner mitochondrial membrane and its evolutionary implications. Mol Biochem Parasitol 2020; 238:111282. [DOI: 10.1016/j.molbiopara.2020.111282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/10/2020] [Accepted: 05/07/2020] [Indexed: 12/18/2022]
|
7
|
The HslV Protease from Leishmania major and Its Activation by C-terminal HslU Peptides. Int J Mol Sci 2019; 20:ijms20051021. [PMID: 30813632 PMCID: PMC6429459 DOI: 10.3390/ijms20051021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/11/2019] [Accepted: 02/20/2019] [Indexed: 12/31/2022] Open
Abstract
HslVU is an ATP-dependent proteolytic complex present in certain bacteria and in the mitochondrion of some primordial eukaryotes, including deadly parasites such as Leishmania. It is formed by the dodecameric protease HslV and the hexameric ATPase HslU, which binds via the C-terminal end of its subunits to HslV and activates it by a yet unclear allosteric mechanism. We undertook the characterization of HslV from Leishmania major (LmHslV), a trypanosomatid that expresses two isoforms for HslU, LmHslU1 and LmHslU2. Using a novel and sensitive peptide substrate, we found that LmHslV can be activated by peptides derived from the C-termini of both LmHslU1 and LmHslU2. Truncations, Ala- and D-scans of the C-terminal dodecapeptide of LmHslU2 (LmC12-U2) showed that five out of the six C-terminal residues of LmHslU2 are essential for binding to and activating HslV. Peptide cyclisation with a lactam bridge allowed shortening of the peptide without loss of potency. Finally, we found that dodecapeptides derived from HslU of other parasites and bacteria are able to activate LmHslV with similar or even higher efficiency. Importantly, using electron microscopy approaches, we observed that the activation of LmHslV was accompanied by a large conformational remodeling, which represents a yet unidentified layer of control of HslV activation.
Collapse
|
8
|
An Insight into the Constitutive Proteome Throughout Leishmania donovani Promastigote Growth and Differentiation. Int Microbiol 2018; 22:143-154. [DOI: 10.1007/s10123-018-00036-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 01/28/2023]
|
9
|
Krishnan A, Burroughs AM, Iyer LM, Aravind L. Unexpected Evolution of Lesion-Recognition Modules in Eukaryotic NER and Kinetoplast DNA Dynamics Proteins from Bacterial Mobile Elements. iScience 2018; 9:192-208. [PMID: 30396152 PMCID: PMC6222260 DOI: 10.1016/j.isci.2018.10.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/15/2018] [Accepted: 10/15/2018] [Indexed: 12/29/2022] Open
Abstract
The provenance of several components of major uniquely eukaryotic molecular machines are increasingly being traced back to prokaryotic biological conflict systems. Here, we demonstrate that the N-terminal single-stranded DNA-binding domain from the anti-restriction protein ArdC, deployed by bacterial mobile elements against their host, was independently acquired twice by eukaryotes, giving rise to the DNA-binding domains of XPC/Rad4 and the Tc-38-like proteins in the stem kinetoplastid. In both instances, the ArdC-N domain tandemly duplicated forming an extensive DNA-binding interface. In XPC/Rad4, the ArdC-N domains (BHDs) also fused to the inactive transglutaminase domain of a peptide-N-glycanase ultimately derived from an archaeal conflict system. Alongside, we delineate several parallel acquisitions from conjugative elements/bacteriophages that gave rise to key components of the kinetoplast DNA (kDNA) replication apparatus. These findings resolve two outstanding questions in eukaryote biology: (1) the origin of the unique DNA lesion-recognition component of NER and (2) origin of the unusual, plasmid-like features of kDNA.
Collapse
Affiliation(s)
- Arunkumar Krishnan
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - A Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Lakshminarayan M Iyer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
| |
Collapse
|
10
|
Concepción-Acevedo J, Miller JC, Boucher MJ, Klingbeil MM. Cell cycle localization dynamics of mitochondrial DNA polymerase IC in African trypanosomes. Mol Biol Cell 2018; 29:2540-2552. [PMID: 30133333 PMCID: PMC6254582 DOI: 10.1091/mbc.e18-02-0127] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Trypanosoma brucei has a unique catenated mitochondrial DNA (mtDNA) network called kinetoplast DNA (kDNA). Replication of kDNA occurs once per cell cycle in near synchrony with nuclear S phase and requires the coordination of many proteins. Among these are three essential DNA polymerases (TbPOLIB, IC, and ID). Localization dynamics of these proteins with respect to kDNA replication stages and how they coordinate their functions during replication are not well understood. We previously demonstrated that TbPOLID undergoes dynamic localization changes that are coupled to kDNA replication events. Here, we report the localization of TbPOLIC, a second essential DNA polymerase, and demonstrate the accumulation of TbPOLIC foci at active kDNA replication sites (antipodal sites) during stage II of the kDNA duplication cycle. While TbPOLIC was undetectable by immunofluorescence during other cell cycle stages, steady-state protein levels measured by Western blot remained constant. TbPOLIC foci colocalized with the fraction of TbPOLID that localized to the antipodal sites. However, the partial colocalization of the two essential DNA polymerases suggests a highly dynamic environment at the antipodal sites to coordinate the trafficking of replication proteins during kDNA synthesis. These data indicate that cell cycle-dependent localization is a major regulatory mechanism for essential mtDNA polymerases during kDNA replication.
Collapse
Affiliation(s)
| | - Jonathan C Miller
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA 01003
| | - Michael J Boucher
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA 01003
| | - Michele M Klingbeil
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA 01003
| |
Collapse
|
11
|
Grewal JS, McLuskey K, Das D, Myburgh E, Wilkes J, Brown E, Lemgruber L, Gould MK, Burchmore RJ, Coombs GH, Schnaufer A, Mottram JC. PNT1 Is a C11 Cysteine Peptidase Essential for Replication of the Trypanosome Kinetoplast. J Biol Chem 2016; 291:9492-500. [PMID: 26940875 PMCID: PMC4850289 DOI: 10.1074/jbc.m116.714972] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Indexed: 11/16/2022] Open
Abstract
The structure of a C11 peptidase PmC11 from the gut bacterium, Parabacteroides merdae, has recently been determined, enabling the identification and characterization of a C11 orthologue, PNT1, in the parasitic protozoon Trypanosoma brucei. A phylogenetic analysis identified PmC11 orthologues in bacteria, archaea, Chromerids, Coccidia, and Kinetoplastida, the latter being the most divergent. A primary sequence alignment of PNT1 with clostripain and PmC11 revealed the position of the characteristic His-Cys catalytic dyad (His99 and Cys136), and an Asp (Asp134) in the potential S1 binding site. Immunofluorescence and cryoelectron microscopy revealed that PNT1 localizes to the kinetoplast, an organelle containing the mitochondrial genome of the parasite (kDNA), with an accumulation of the protein at or near the antipodal sites. Depletion of PNT1 by RNAi in the T. brucei bloodstream form was lethal both in in vitro culture and in vivo in mice and the induced population accumulated cells lacking a kinetoplast. In contrast, overexpression of PNT1 led to cells having mislocated kinetoplasts. RNAi depletion of PNT1 in a kDNA independent cell line resulted in kinetoplast loss but was viable, indicating that PNT1 is required exclusively for kinetoplast maintenance. Expression of a recoded wild-type PNT1 allele, but not of an active site mutant restored parasite viability after induction in vitro and in vivo confirming that the peptidase activity of PNT1 is essential for parasite survival. These data provide evidence that PNT1 is a cysteine peptidase that is required exclusively for maintenance of the trypanosome kinetoplast.
Collapse
Affiliation(s)
- Jaspreet S Grewal
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom, the Department of Biology, Centre for Immunology and Infection, University of York, Wentworth Way, Heslington, York YO10 5DD, United Kingdom
| | - Karen McLuskey
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Debanu Das
- the Joint Center for Structural Genomics, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025
| | - Elmarie Myburgh
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom, the Department of Biology, Centre for Immunology and Infection, University of York, Wentworth Way, Heslington, York YO10 5DD, United Kingdom
| | - Jonathan Wilkes
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Elaine Brown
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom, the Department of Biology, Centre for Immunology and Infection, University of York, Wentworth Way, Heslington, York YO10 5DD, United Kingdom
| | - Leandro Lemgruber
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Matthew K Gould
- the Institute of Immunology and Infection Research and Centre for Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Richard J Burchmore
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Graham H Coombs
- the Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, United Kingdom
| | - Achim Schnaufer
- the Institute of Immunology and Infection Research and Centre for Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Jeremy C Mottram
- From the Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom, the Department of Biology, Centre for Immunology and Infection, University of York, Wentworth Way, Heslington, York YO10 5DD, United Kingdom,
| |
Collapse
|
12
|
Chang CY, Hu HT, Tsai CH, Wu WF. The degradation of RcsA by ClpYQ(HslUV) protease in Escherichia coli. Microbiol Res 2016; 184:42-50. [PMID: 26856452 DOI: 10.1016/j.micres.2016.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/21/2015] [Accepted: 01/09/2016] [Indexed: 01/30/2023]
Abstract
In Escherichia coli, RcsA, a positive activator for transcription of cps (capsular polysaccharide synthesis) genes, is degraded by the Lon protease. In lon mutant, the accumulation of RcsA leads to overexpression of capsular polysaccharide. In a previous study, overproduction of ClpYQ(HslUV) protease represses the expression of cpsB∷lacZ, but there has been no direct observation demonstrating that ClpYQ degrades RcsA. By means of a MBP-RcsA fusion protein, we showed that RcsA activated cpsB∷lacZ expression and could be rapidly degraded by Lon protease in SG22622 (lon(+)). Subsequently, the comparative half-life experiments performed in the bacterial strains SG22623 (lon) and AC3112 (lon clpY clpQ) indicated that the RcsA turnover rate in AC3112 was relatively slow and RcsA was stable at 30°C or 41°C. In addition, ClpY could interact with RscA in an in vitro pull-down assay, and the more rapid degradation of RcsA was observed in the presence of ClpYQ protease at 41°C. Thus, we conclude that RcsA is indeed proteolized by ClpYQ protease.
Collapse
Affiliation(s)
- Chun-Yang Chang
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC
| | - Hui-Ting Hu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC
| | - Chih-Hsuan Tsai
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC
| | - Whei-Fen Wu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC.
| |
Collapse
|
13
|
Molecular Chaperones of Leishmania: Central Players in Many Stress-Related and -Unrelated Physiological Processes. BIOMED RESEARCH INTERNATIONAL 2015; 2015:301326. [PMID: 26167482 PMCID: PMC4488524 DOI: 10.1155/2015/301326] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Accepted: 05/24/2015] [Indexed: 12/12/2022]
Abstract
Molecular chaperones are key components in the maintenance of cellular homeostasis and survival, not only during stress but also under optimal growth conditions. Folding of nascent polypeptides is supported by molecular chaperones, which avoid the formation of aggregates by preventing nonspecific interactions and aid, when necessary, the translocation of proteins to their correct intracellular localization. Furthermore, when proteins are damaged, molecular chaperones may also facilitate their refolding or, in the case of irreparable proteins, their removal by the protein degradation machinery of the cell. During their digenetic lifestyle, Leishmania parasites encounter and adapt to harsh environmental conditions, such as nutrient deficiency, hypoxia, oxidative stress, changing pH, and shifts in temperature; all these factors are potential triggers of cellular stress. We summarize here our current knowledge on the main types of molecular chaperones in Leishmania and their functions. Among them, heat shock proteins play important roles in adaptation and survival of this parasite against temperature changes associated with its passage from the poikilothermic insect vector to the warm-blooded vertebrate host. The study of structural features and the function of chaperones in Leishmania biology is providing opportunities (and challenges) for drug discovery and improving of current treatments against leishmaniasis.
Collapse
|
14
|
Kammers K, Cole RN, Tiengwe C, Ruczinski I. Detecting Significant Changes in Protein Abundance. EUPA OPEN PROTEOMICS 2015; 7:11-19. [PMID: 25821719 DOI: 10.1016/j.euprot.2015.02.002] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We review and demonstrate how an empirical Bayes method, shrinking a protein's sample variance towards a pooled estimate, leads to far more powerful and stable inference to detect significant changes in protein abundance compared to ordinary t-tests. Using examples from isobaric mass labeled proteomic experiments we show how to analyze data from multiple experiments simultaneously, and discuss the effects of missing data on the inference. We also present easy to use open source software for normalization of mass spectrometry data and inference based on moderated test statistics.
Collapse
Affiliation(s)
- Kai Kammers
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Robert N Cole
- Mass Spectrometry and Proteomics Core Facility, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Calvin Tiengwe
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA. ; Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Bu alo, Bu alo, NY, USA
| | - Ingo Ruczinski
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| |
Collapse
|
15
|
Verner Z, Basu S, Benz C, Dixit S, Dobáková E, Faktorová D, Hashimi H, Horáková E, Huang Z, Paris Z, Peña-Diaz P, Ridlon L, Týč J, Wildridge D, Zíková A, Lukeš J. Malleable mitochondrion of Trypanosoma brucei. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:73-151. [PMID: 25708462 DOI: 10.1016/bs.ircmb.2014.11.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The importance of mitochondria for a typical aerobic eukaryotic cell is undeniable, as the list of necessary mitochondrial processes is steadily growing. Here, we summarize the current knowledge of mitochondrial biology of an early-branching parasitic protist, Trypanosoma brucei, a causative agent of serious human and cattle diseases. We present a comprehensive survey of its mitochondrial pathways including kinetoplast DNA replication and maintenance, gene expression, protein and metabolite import, major metabolic pathways, Fe-S cluster synthesis, ion homeostasis, organellar dynamics, and other processes. As we describe in this chapter, the single mitochondrion of T. brucei is everything but simple and as such rivals mitochondria of multicellular organisms.
Collapse
Affiliation(s)
- Zdeněk Verner
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Present address: Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia; Present address: Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Somsuvro Basu
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic; Present address: Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Germany
| | - Corinna Benz
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Sameer Dixit
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Eva Dobáková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Present address: Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Drahomíra Faktorová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Hassan Hashimi
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Eva Horáková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Zhenqiu Huang
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Zdeněk Paris
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Priscila Peña-Diaz
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Lucie Ridlon
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic; Present address: Salk Institute, La Jolla, San Diego, USA
| | - Jiří Týč
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - David Wildridge
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Alena Zíková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| |
Collapse
|
16
|
Abstract
I knew nothing and had thought nothing about parasites until 1971. In fact, if you had asked me before then, I might have commented that parasites were rather disgusting. I had been at the Johns Hopkins School of Medicine for three years, and I was on the lookout for a new project. In 1971, I came across a paper in the Journal of Molecular Biology by Larry Simpson, a classmate of mine in graduate school. Larry's paper described a remarkable DNA structure known as kinetoplast DNA (kDNA), isolated from a parasite. kDNA, the mitochondrial genome of trypanosomatids, is a DNA network composed of several thousand interlocked DNA rings. Almost nothing was known about it. I was looking for a project on DNA replication, and I wanted it to be both challenging and important. I had no doubt that working with kDNA would be a challenge, as I would be exploring uncharted territory. I was also sure that the project would be important when I learned that parasites with kDNA threaten huge populations in underdeveloped tropical countries. Looking again at Larry's paper, I found the electron micrographs of the kDNA networks to be rather beautiful. I decided to take a chance on kDNA. Little did I know then that I would devote the next forty years of my life to studying kDNA replication.
Collapse
Affiliation(s)
- Paul T Englund
- From the Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| |
Collapse
|
17
|
Bochman ML. Roles of DNA helicases in the maintenance of genome integrity. Mol Cell Oncol 2014; 1:e963429. [PMID: 27308340 PMCID: PMC4905024 DOI: 10.4161/23723548.2014.963429] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 07/25/2014] [Accepted: 09/01/2014] [Indexed: 11/19/2022]
Abstract
Genome integrity is achieved and maintained by the sum of all of the processes in the cell that ensure the faithful duplication and repair of DNA, as well as its genetic transmission from one cell division to the next. As central players in virtually all of the DNA transactions that occur in vivo, DNA helicases (molecular motors that unwind double-stranded DNA to produce single-stranded substrates) represent a crucial enzyme family that is necessary for genomic stability. Indeed, mutations in many human helicase genes are linked to a variety of diseases with symptoms that can be generally described as genomic instability, such as predispositions to cancers. This review focuses on the roles of both DNA replication helicases and recombination/repair helicases in maintaining genome integrity and provides a brief overview of the diseases related to defects in these enzymes.
Collapse
Affiliation(s)
- Matthew L Bochman
- Molecular and Cellular Biochemistry Department; Indiana University ; Bloomington, IN USA
| |
Collapse
|
18
|
Sung KH, Song HK. Insights into the molecular evolution of HslU ATPase through biochemical and mutational analyses. PLoS One 2014; 9:e103027. [PMID: 25050622 PMCID: PMC4106860 DOI: 10.1371/journal.pone.0103027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 06/26/2014] [Indexed: 11/18/2022] Open
Abstract
The ATP-dependent HslVU complexes are found in all three biological kingdoms. A single HslV protease exists in each species of prokaryotes, archaea, and eukaryotes, but two HslUs (HslU1 and HslU2) are present in the mitochondria of eukaryotes. Previously, a tyrosine residue at the C-terminal tail of HslU2 has been identified as a key determinant of HslV activation in Trypanosoma brucei and a phenylalanine at the equivalent position to E. coli HslU is found in T. brucei HslU1. Unexpectedly, we found that an F441Y mutation in HslU enhanced the peptidase and caseinolytic activity of HslV in E. coli but it showed partially reduced ATPase and SulA degradation activity. Previously, only the C-terminal tail of HslU has been the focus of HslV activation studies. However, the Pro315 residue interacting with Phe441 in free HslU has also been found to be critical for HslV activation. Hence, our current biochemical analyses explore the importance of the loop region just before Pro315 for HslVU complex functionality. The proline and phenylalanine pair in prokaryotic HslU was replaced with the threonine and tyrosine pair from the functional eukaryotic HslU2. Sequence comparisons between multiple HslUs from three different biological kingdoms in combination with biochemical analysis of E. coli mutants have uncovered important new insights into the molecular evolutionary pathway of HslU.
Collapse
Affiliation(s)
| | - Hyun Kyu Song
- Department of Life Sciences, Korea University, Seoul, Korea
- * E-mail:
| |
Collapse
|
19
|
Gawryluk RMR, Chisholm KA, Pinto DM, Gray MW. Compositional complexity of the mitochondrial proteome of a unicellular eukaryote (Acanthamoeba castellanii, supergroup Amoebozoa) rivals that of animals, fungi, and plants. J Proteomics 2014; 109:400-16. [PMID: 25026440 DOI: 10.1016/j.jprot.2014.07.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 06/09/2014] [Accepted: 07/04/2014] [Indexed: 12/22/2022]
Abstract
UNLABELLED We present a combined proteomic and bioinformatic investigation of mitochondrial proteins from the amoeboid protist Acanthamoeba castellanii, the first such comprehensive investigation in a free-living member of the supergroup Amoebozoa. This protist was chosen both for its phylogenetic position (as a sister to animals and fungi) and its ecological ubiquity and physiological flexibility. We report 1033 A. castellanii mitochondrial protein sequences, 709 supported by mass spectrometry data (676 nucleus-encoded and 33 mitochondrion-encoded), including two previously unannotated mtDNA-encoded proteins, which we identify as highly divergent mitochondrial ribosomal proteins. Other notable findings include duplicate proteins for all of the enzymes of the tricarboxylic acid (TCA) cycle-which, along with the identification of a mitochondrial malate synthase-isocitrate lyase fusion protein, suggests the interesting possibility that the glyoxylate cycle operates in A. castellanii mitochondria. Additionally, the A. castellanii genome encodes an unusually high number (at least 29) of mitochondrion-targeted pentatricopeptide repeat (PPR) proteins, organellar RNA metabolism factors in other organisms. We discuss several key mitochondrial pathways, including DNA replication, transcription and translation, protein degradation, protein import and Fe-S cluster biosynthesis, highlighting similarities and differences in these pathways in other eukaryotes. In compositional and functional complexity, the mitochondrial proteome of A. castellanii rivals that of multicellular eukaryotes. BIOLOGICAL SIGNIFICANCE Comprehensive proteomic surveys of mitochondria have been undertaken in a limited number of predominantly multicellular eukaryotes. This phylogenetically narrow perspective constrains and biases our insights into mitochondrial function and evolution, as it neglects protists, which account for most of the evolutionary and functional diversity within eukaryotes. We report here the first comprehensive investigation of the mitochondrial proteome in a member (A. castellanii) of the eukaryotic supergroup Amoebozoa. Through a combination of tandem mass spectrometry (MS/MS) and in silico data mining, we have retrieved 1033 candidate mitochondrial protein sequences, 709 having MS support. These data were used to reconstruct the metabolic pathways and protein complexes of A. castellanii mitochondria, and were integrated with data from other characterized mitochondrial proteomes to augment our understanding of mitochondrial proteome evolution. Our results demonstrate the power of combining direct proteomic and bioinformatic approaches in the discovery of novel mitochondrial proteins, both nucleus-encoded and mitochondrion-encoded, and highlight the compositional complexity of the A. castellanii mitochondrial proteome, which rivals that of animals, fungi and plants.
Collapse
Affiliation(s)
- Ryan M R Gawryluk
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kenneth A Chisholm
- Mass Spectrometry and Proteomics Group, National Research Council of Canada, Halifax, Nova Scotia, Canada
| | - Devanand M Pinto
- Mass Spectrometry and Proteomics Group, National Research Council of Canada, Halifax, Nova Scotia, Canada
| | - Michael W Gray
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
| |
Collapse
|
20
|
Povelones ML. Beyond replication: division and segregation of mitochondrial DNA in kinetoplastids. Mol Biochem Parasitol 2014; 196:53-60. [PMID: 24704441 DOI: 10.1016/j.molbiopara.2014.03.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/18/2014] [Accepted: 03/25/2014] [Indexed: 11/29/2022]
Abstract
The mitochondrial genome of kinetoplastids, called kinetoplast DNA (kDNA) is a complex structure that must be faithfully duplicated exactly once per cell cycle. Despite many years of thorough investigation into the kDNA replication mechanism, many of the molecular details of the later stages of the process, particularly kDNA division and segregation, remain mysterious. In addition, perturbation of several cellular activities, some only indirectly related to kDNA, can lead to asymmetric kDNA division and other segregation defects. This review will examine unifying features and possible explanations for these phenotypes in the context of current models for kDNA division and segregation.
Collapse
|
21
|
Mbang-Benet DE, Sterkers Y, Morelle C, Kebe NM, Crobu L, Portalès P, Coux O, Hernandez JF, Meghamla S, Pagès M, Bastien P. The bacterial-like HslVU protease complex subunits are involved in the control of different cell cycle events in trypanosomatids. Acta Trop 2014; 131:22-31. [PMID: 24299926 DOI: 10.1016/j.actatropica.2013.11.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 11/16/2013] [Accepted: 11/21/2013] [Indexed: 02/08/2023]
Abstract
The trypanosomatid parasites Leishmania and Trypanosoma are responsible for the most important WHO-designated neglected tropical diseases, for which the need for cost-effective new drugs is urgent. In addition to the classical eukaryotic 20S and 26S proteasomes, these unconventional eukaryotes possess a bacterial-like protease complex, HslVU, made of proteolytic (HslV) and regulatory (HslU) subunits. In trypanosomatids, two paralogous genes are co-expressed: HslU1 and HslU2. Conflicting reports have been published with respect to subcellular localization, functional redundancy and putative roles of the different subunits of this complex in trypanosomatids. Here, we definitively established the mitochondrial localization of HslVU in L. major procyclic promastigotes and of HslV in T. brucei bloodstream trypomastigotes, the latter being the form responsible for the disease in the mammalian host. Moreover, our data demonstrate for the first time the essential nature of HslVU in the bloodstream trypomastigotes of T. brucei, in spite of mitochondrial repression at this stage. Interestingly, our work also allows distinguishing a specific role for the different members of the complex, as HslV and HslU1 appear to be involved in the control of different cell cycle events. Finally, these data validate HslVU as a promising drug target against these parasitic diseases of wide medical and economical importance.
Collapse
|
22
|
Zhou Q, Hu H, Li Z. New insights into the molecular mechanisms of mitosis and cytokinesis in trypanosomes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 308:127-66. [PMID: 24411171 DOI: 10.1016/b978-0-12-800097-7.00004-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Trypanosoma brucei, a unicellular eukaryote and the causative agent of human sleeping sickness, possesses multiple single-copy organelles that all need to be duplicated and segregated during cell division. Trypanosomes undergo a closed mitosis in which the mitotic spindle is anchored on the nuclear envelope and connects the kinetochores made of novel protein components. Cytokinesis in trypanosomes is initiated from the anterior tip of the new flagellum attachment zone, and proceeds along the longitudinal axis without the involvement of the actomyosin contractile ring, the well-recognized cytokinesis machinery conserved from yeast to humans. Trypanosome appears to employ both evolutionarily conserved and trypanosome-specific proteins to regulate its cell cycle, and has evolved certain cell cycle regulatory pathways that are either distinct between its life cycle stages or different from its human host. Understanding the mechanisms of mitosis and cytokinesis in trypanosomes not only would shed novel light on the evolution of cell cycle control, but also could provide new drug targets for chemotherapy.
Collapse
Affiliation(s)
- Qing Zhou
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Huiqing Hu
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, USA.
| |
Collapse
|
23
|
Sung KH, Lee SY, Song HK. Structural and biochemical analyses of the eukaryotic heat shock locus V (HslV) from Trypanosoma brucei. J Biol Chem 2013; 288:23234-43. [PMID: 23818520 DOI: 10.1074/jbc.m113.484832] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In many bacteria, heat shock locus V (HslV) functions as a protease, which is activated by heat shock locus U (HslU). The primary sequence and structure of HslV are well conserved with those of the β-subunit of the 20 S proteasome core particle in eukaryotes. To date, the HslVU complex has only been characterized in the prokaryotic system. Recently, however, the coexistence of a 20 S proteasome with HslV protease in the same living organism has been reported. In Trypanosoma brucei, a protozoan parasite that causes human sleeping sickness in Africa, HslV is localized in the mitochondria, where it has a novel function in regulating mitochondrial DNA replication. Although the prokaryotic HslVU system has been studied extensively, little is known regarding its eukaryotic counterpart. Here, we report the biochemical characteristics of an HslVU complex from T. brucei. In contrast to the prokaryotic system, T. brucei possesses two potential HslU molecules, and we found that only one of them activates HslV. A key activating residue, Tyr(494), was identified in HslU2 by biochemical and mutational studies. Furthermore, to our knowledge, this study is the first to report the crystal structure of a eukaryotic HslV, determined at 2.4 Å resolution. Drawing on our comparison of the biochemical and structural data, we discuss herein the differences and similarities between eukaryotic and prokaryotic HslVs.
Collapse
Affiliation(s)
- Kwang Hoon Sung
- Department of Life Sciences, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-701, Korea
| | | | | |
Collapse
|
24
|
Trypanosoma brucei Tb927.2.6100 is an essential protein associated with kinetoplast DNA. EUKARYOTIC CELL 2013; 12:970-8. [PMID: 23650088 DOI: 10.1128/ec.00352-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mitochondrial DNA of trypanosomatid protozoa consists of a complex, intercatenated network of tens of maxicircles and thousands of minicircles. This structure, called kinetoplast DNA (kDNA), requires numerous proteins and multiprotein complexes for replication, segregation, and transcription. In this study, we used a proteomic approach to identify proteins that are associated with the kDNA network. We identified a novel protein encoded by Tb927.2.6100 that was present in a fraction enriched for kDNA and colocalized the protein with kDNA by fluorescence microscopy. RNA interference (RNAi) knockdown of its expression resulted in a growth defect and changes in the proportion of kinetoplasts and nuclei in the cell population. RNAi also resulted in shrinkage and loss of the kinetoplasts, loss of maxicircle and minicircle components of kDNA at similar rates, and (perhaps secondarily) loss of edited and pre-edited mRNA. These results indicate that the Tb927.2.6100 protein is essential for the maintenance of kDNA.
Collapse
|
25
|
Jain S, Rathore S, Asad M, Hossain ME, Sinha D, Datta G, Mohmmed A. The prokaryotic ClpQ protease plays a key role in growth and development of mitochondria in Plasmodium falciparum. Cell Microbiol 2013; 15:1660-73. [PMID: 23521916 DOI: 10.1111/cmi.12142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 02/18/2013] [Accepted: 03/14/2013] [Indexed: 01/17/2023]
Abstract
The ATP-dependent ClpQY system is a prokaryotic proteasome-like multi-subunit machinery localized in the mitochondrion of malaria parasite. The ClpQY machinery consists of ClpQ threonine protease and ClpY ATPase. In the present study, we have assessed cellular effects of transient interference of PfClpQ protease activity in Plasmodium falciparum using a trans-dominant negative approach combined with FKBP degradation domain system. A proteolytically inactive mutant PfClpQ protein [PfClpQ(mut)] fused with FKBP degradation domain was expressed in parasites, which gets stabilized by Shield1 drug treatment. We show that the inactive PfClpQ(mut) interacts with wild-type PfClpQ and associates within multi-subunit complex in the parasite. Stabilization of the PfClpQ(mut) and its association in the protease machinery caused dominant negative effect in the transgenic parasites, which disrupted the growth cycle of asexual blood stage parasites. The mitochondria in these parasites showed abnormal morphology, these mitochondria were not able to grow and divide in the parasite. We further show that the dominant negative effect of PfClpQ(mut) disrupted transcription of mitochondrial genome encoded genes, which in turn blocked normal development and functioning of the mitochondria.
Collapse
Affiliation(s)
- Shaifali Jain
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110 067, India
| | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
One of the most fascinating and unusual features of trypanosomatids, parasites that cause disease in many tropical countries, is their mitochondrial DNA. This genome, known as kinetoplast DNA (kDNA), is organized as a single, massive DNA network formed of interlocked DNA rings. In this review, we discuss recent studies on kDNA structure and replication, emphasizing recent developments on replication enzymes, how the timing of kDNA synthesis is controlled during the cell cycle, and the machinery for segregating daughter networks after replication.
Collapse
Affiliation(s)
- Robert E Jensen
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
| | | |
Collapse
|
27
|
Povelones ML, Tiengwe C, Gluenz E, Gull K, Englund PT, Jensen RE. Mitochondrial shape and function in trypanosomes requires the outer membrane protein, TbLOK1. Mol Microbiol 2013; 87:713-29. [PMID: 23336702 DOI: 10.1111/mmi.12089] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2012] [Indexed: 01/01/2023]
Abstract
In an RNAi library screen for loss of kinetoplast DNA (kDNA), we identified an uncharacterized Trypanosoma brucei protein, named TbLOK1, required for maintenance of mitochondrial shape and function. We found the TbLOK1 protein located in discrete patches in the mitochondrial outer membrane. Knock-down of TbLOK1 in procyclic trypanosomes caused the highly interconnected mitochondrial structure to collapse, forming an unbranched tubule remarkably similar to the streamlined organelle seen in the bloodstream form. Following RNAi, defects in mitochondrial respiration, inner membrane potential and mitochondrial transcription were observed. At later times following TbLOK1 depletion, kDNA was lost and a more drastic alteration in mitochondrial structure was found. Our results demonstrate the close relationship between organelle structure and function in trypanosomes.
Collapse
Affiliation(s)
- Megan L Povelones
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | | | | | | | | |
Collapse
|
28
|
Abstract
The cell division cycle is tightly regulated by the activation and inactivation of a series of proteins that control the replication and segregation of organelles to the daughter cells. During the past decade, we have witnessed significant advances in our understanding of the cell cycle in Trypanosoma brucei and how the cycle is regulated by various regulatory proteins. However, many other regulators, especially those unique to trypanosomes, remain to be identified, and we are just beginning to delineate the signaling pathways that drive the transitions through different cell cycle stages, such as the G(1)/S transition, G(2)/M transition, and mitosis-cytokinesis transition. Trypanosomes appear to employ both evolutionarily conserved and trypanosome-specific molecules to regulate the various stages of its cell cycle, including DNA replication initiation, spindle assembly, chromosome segregation, and cytokinesis initiation and completion. Strikingly, trypanosomes lack some crucial regulators that are well conserved across evolution, such as Cdc6 and Cdt1, which are involved in DNA replication licensing, the spindle motor kinesin-5, which is required for spindle assembly, the central spindlin complex, which has been implicated in cytokinesis initiation, and the actomyosin contractile ring, which is located at the cleavage furrow. Conversely, trypanosomes possess certain regulators, such as cyclins, cyclin-dependent kinases, and mitotic centromere-associated kinesins, that are greatly expanded and likely play diverse cellular functions. Overall, trypanosomes apparently have integrated unique regulators into the evolutionarily conserved pathways to compensate for the absence of those conserved molecules and, additionally, have evolved certain cell cycle regulatory pathways that are either different from its human host or distinct between its own life cycle forms.
Collapse
|
29
|
The influence of ATP-dependent proteases on a variety of nucleoid-associated processes. J Struct Biol 2012; 179:181-92. [PMID: 22683345 DOI: 10.1016/j.jsb.2012.05.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 05/24/2012] [Accepted: 05/26/2012] [Indexed: 01/07/2023]
Abstract
ATP-dependent proteases are crucial components of all living cells and are involved in a variety of responses to physiological and environmental changes. Nucleoids are dynamic nucleoprotein complexes present in bacteria and eukaryotic organelles (mitochondria and plastids) and are the place where the majority of cellular responses to stress begin. These structures are actively remodeled in reaction to changing environmental and physiological conditions. The levels of nucleoid protein components (e.g. DNA-stabilizing proteins, transcription factors, replication proteins) therefore have to be continually regulated. ATP-dependent proteases have all the characteristics needed to fulfill this requirement. Some of them bind nucleic acids, but above all, they control and maintain the level of many DNA-binding proteins. In this review we will discuss the roles of the Lon, ClpAP, ClpXP, HslUV and FtsH proteases in the maintenance, stability, transcription and repair of DNA in eubacterial and mitochondrial nucleoids.
Collapse
|
30
|
Leishmania donovani HslV does not interact stably with HslU proteins. Int J Parasitol 2012; 42:329-39. [PMID: 22370310 DOI: 10.1016/j.ijpara.2012.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 01/10/2012] [Accepted: 01/16/2012] [Indexed: 11/21/2022]
Abstract
Genes for HslVU-type peptidases are found in bacteria and in a few select Eukaryota, among those such important pathogens as Plasmodium spp. and Leishmania spp. In this study, we performed replacements of all three HslV/HslU gene homologues and found one of those, HslV, to be essential for Leishmania donovani viability. The Leishmania HslV gene can also partially relieve the thermosensitive phenotype of a combined HslVU/Lon/ClpXP knockout mutant of Escherichia coli, indicating a conserved function. However, we found that the role and function of the two Leishmania HslU genes has diverged since neither of those interacts stably with HslV. The latter forms a dodecameric complex by itself and shows a punctate distribution. We conclude that whilst the basic function of HslV may be conserved in Leishmania, its organisation and interaction with its canonical complex partner HslU is not. Nevertheless, given the absence of HslV from the proteome of mammals and its essential role in Leishmania viability, HslV is a promising target for intervention.
Collapse
|
31
|
Dynamic localization of Trypanosoma brucei mitochondrial DNA polymerase ID. EUKARYOTIC CELL 2012; 11:844-55. [PMID: 22286095 DOI: 10.1128/ec.05291-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Trypanosomes contain a unique form of mitochondrial DNA called kinetoplast DNA (kDNA) that is a catenated network composed of minicircles and maxicircles. Several proteins are essential for network replication, and most of these localize to the antipodal sites or the kinetoflagellar zone. Essential components for kDNA synthesis include three mitochondrial DNA polymerases TbPOLIB, TbPOLIC, and TbPOLID). In contrast to other kDNA replication proteins, TbPOLID was previously reported to localize throughout the mitochondrial matrix. This spatial distribution suggests that TbPOLID requires redistribution to engage in kDNA replication. Here, we characterize the subcellular distribution of TbPOLID with respect to the Trypanosoma brucei cell cycle using immunofluorescence microscopy. Our analyses demonstrate that in addition to the previously reported matrix localization, TbPOLID was detected as discrete foci near the kDNA. TbPOLID foci colocalized with replicating minicircles at antipodal sites in a specific subset of the cells during stages II and III of kDNA replication. Additionally, the TbPOLID foci were stable following the inhibition of protein synthesis, detergent extraction, and DNase treatment. Taken together, these data demonstrate that TbPOLID has a dynamic localization that allows it to be spatially and temporally available to perform its role in kDNA replication.
Collapse
|
32
|
Aminake MN, Arndt HD, Pradel G. The proteasome of malaria parasites: A multi-stage drug target for chemotherapeutic intervention? INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2012; 2:1-10. [PMID: 24533266 DOI: 10.1016/j.ijpddr.2011.12.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/21/2011] [Accepted: 12/24/2011] [Indexed: 12/13/2022]
Abstract
The ubiquitin/proteasome system serves as a regulated protein degradation pathway in eukaryotes, and is involved in many cellular processes featuring high protein turnover rates, such as cell cycle control, stress response and signal transduction. In malaria parasites, protein quality control is potentially important because of the high replication rate and the rapid transformations of the parasite during life cycle progression. The proteasome is the core of the degradation pathway, and is a major proteolytic complex responsible for the degradation and recycling of non-functional ubiquitinated proteins. Annotation of the genome for Plasmodium falciparum, the causative agent of malaria tropica, revealed proteins with similarity to human 26S proteasome subunits. In addition, a bacterial ClpQ/hslV threonine peptidase-like protein was identified. In recent years several independent studies indicated an essential function of the parasite proteasome for the liver, blood and transmission stages. In this review, we compile evidence for protein recycling in Plasmodium parasites and discuss the role of the 26S proteasome as a prospective multi-stage target for antimalarial drug discovery programs.
Collapse
Affiliation(s)
- Makoah Nigel Aminake
- Julius-Maximilians-University Würzburg, Research Center for Infectious Diseases, Josef-Schneider-Str. 2/D15, 97080 Würzburg, Germany
| | - Hans-Dieter Arndt
- Friedrich-Schiller-University Jena, Chair of Organic Chemistry I, Humboldtstr. 10, 07743 Jena, Germany
| | - Gabriele Pradel
- Julius-Maximilians-University Würzburg, Research Center for Infectious Diseases, Josef-Schneider-Str. 2/D15, 97080 Würzburg, Germany
| |
Collapse
|
33
|
Abstract
The ubiquitin-proteasomal system is an essential element of the protein quality control machinery in cells. The central part of this system is the 20S proteasome. The proteasome is a barrel-shaped multienzyme complex, containing several active centers hidden at the inner surface of the hollow cylinder. So, the regulation of the substrate entry toward the inner proteasomal surface is a key control mechanism of the activity of this protease. This chapter outlines the knowledge on the structure of the subunits of the 20S proteasome, the binding and structure of some proteasomal regulators and inducible proteasomal subunits. Therefore, this chapter imparts the knowledge on proteasomal structure which is required for the understanding of the following chapters.
Collapse
|
34
|
Disruption of a mitochondrial protease machinery in Plasmodium falciparum is an intrinsic signal for parasite cell death. Cell Death Dis 2011; 2:e231. [PMID: 22113196 PMCID: PMC3223699 DOI: 10.1038/cddis.2011.118] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The ATP-dependent ClpQY protease system in Plasmodium falciparum is a prokaryotic machinery in the parasite. In the present study, we have identified the complete ClpQY system in P. falciparum and elucidated its functional importance in survival and growth of asexual stage parasites. We characterized the interaction of P. falciparum ClpQ protease (PfClpQ) and PfClpY ATPase components, and showed that a short stretch of residues at the C terminus of PfClpY has an important role in this interaction; a synthetic peptide corresponding to this region antagonizes this interaction and interferes with the functioning of this machinery in the parasite. Disruption of ClpQY function by this peptide caused hindrance in the parasite growth and maturation of asexual stages of parasites. Detailed analyses of cellular effects in these parasites showed features of apoptosis-like cell death. The peptide-treated parasites showed mitochondrial dysfunction and loss of mitochondrial membrane potential. Dysfunctioning of mitochondria initiated a cascade of reactions in parasites, including activation of VAD-FMK-binding proteases and nucleases, which resulted in apoptosis-like cell death. These results show functional importance of mitochondrial proteases in the parasite and involvement of mitochondria in programmed cell death in the malaria parasites.
Collapse
|
35
|
Barboza NR, Cardoso J, de Paula Lima CV, Soares MJ, Gradia DF, Hangai NS, Bahia MT, de Lana M, Krieger MA, Guerra de Sá R. Expression profile and subcellular localization of HslV, the proteasome related protease from Trypanosoma cruzi. Exp Parasitol 2011; 130:171-7. [PMID: 22085770 DOI: 10.1016/j.exppara.2011.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 10/11/2011] [Accepted: 10/31/2011] [Indexed: 10/15/2022]
Abstract
Trypanosoma cruzi is a rare example of an eukaryote that has genes for two threonine proteases: HslVU complex and 20S proteasome. HslVU is an ATP-dependent protease consisting of two multimeric components: the HslU ATPase and the HslV peptidase. In this study, we expressed and obtained specific antibodies to HslU and HslV recombinant proteins and demonstrated the interaction between HslU/HslV by coimmunoprecipitation. To evaluate the intracellular distribution of HslV in T. cruzi we used an immunofluorescence assay and ultrastructural localization by transmission electron microscopy. Both techniques demonstrated that HslV was localized in the kinetoplast of epimastigotes. We also analyzed the HslV/20S proteasome co-expression in Y, Berenice 62 (Be-62) and Berenice 78 (Be-78) T. cruzi strains. Our results showed that HslV and 20S proteasome are differently expressed in these strains. To investigate whether a proteasome inhibitor could modulate HslV and proteasome expressions, epimastigotes from T. cruzi were grown in the presence of PSI, a classical proteasome inhibitor. This result showed that while the level of expression of HslV/20S proteasome is not affected in Be-78 strain, in Y and Be-62 strains the presence of PSI induced a significantly increase in Hslv/20S proteasome expression. Together, these results suggest the coexistence of the protease HslVU and 20S proteasome in T. cruzi, reinforcing the hypothesis that non-lysosomal degradation pathways have an important role in T. cruzi biology.
Collapse
Affiliation(s)
- Natália Rocha Barboza
- Departamento de Ciências Biológicas & NUPEB, Instituto de Ciências Exatas e Biológica, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400-000 Ouro Preto, MG, Brazil.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Tschan S, Mordmüller B, Kun JFJ. Threonine peptidases as drug targets against malaria. Expert Opin Ther Targets 2011; 15:365-78. [PMID: 21281254 DOI: 10.1517/14728222.2011.555399] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Malaria is caused by the intracellular parasite Plasmodium falciparum. Although numerous therapies are available to fight the disease, the number of pharmacophores is small, and constant development of novel therapies, especially with new targets, is desirable to fight developing resistance against presently prescribed drugs. AREAS COVERED This review discusses research on plasmodial threonine peptidases along with recent advances in proteasome inhibitor development. EXPERT OPINION While PfHslV is an attractive drug target in malaria, more investigation is required to clarify its functional role in the parasite. More efforts should also be invested in assessing the plasmodial proteasome as a drug target. The few papers investigating the effect of proteasome inhibitors on different stages of the life cycle point towards important roles not only during asexual, but also in hepatic and sexual stages, in humans and the mosquito. If this holds true, this is a key argument to further develop proteasome inhibitors for use against malaria.
Collapse
Affiliation(s)
- Serena Tschan
- University of Tübingen, Institute of Tropical Medicine, Wilhelmstr. 27, 72074 Tübingen, Germany
| | | | | |
Collapse
|
37
|
Depletion of mitochondrial acyl carrier protein in bloodstream-form Trypanosoma brucei causes a kinetoplast segregation defect. EUKARYOTIC CELL 2011; 10:286-92. [PMID: 21239625 DOI: 10.1128/ec.00290-10] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Like other eukaryotes, trypanosomes have an essential type II fatty acid synthase in their mitochondrion. We have investigated the function of this synthase in bloodstream-form parasites by studying the effect of a conditional knockout of acyl carrier protein (ACP), a key player in this fatty acid synthase pathway. We found that ACP depletion not only caused small changes in cellular phospholipids but also, surprisingly, caused changes in the kinetoplast. This structure, which contains the mitochondrial genome in the form of a giant network of several thousand interlocked DNA rings (kinetoplast DNA [kDNA]), became larger in some cells and smaller or absent in others. We observed the same pattern in isolated networks viewed by either fluorescence or electron microscopy. We found that the changes in kDNA size were not due to the disruption of replication but, instead, to a defect in segregation. kDNA segregation is mediated by the tripartite attachment complex (TAC), and we hypothesize that one of the TAC components, a differentiated region of the mitochondrial double membrane, has an altered phospholipid composition when ACP is depleted. We further speculate that this compositional change affects TAC function, and thus kDNA segregation.
Collapse
|
38
|
Jacobs RT, Nare B, Phillips MA. State of the art in African trypanosome drug discovery. Curr Top Med Chem 2011; 11:1255-74. [PMID: 21401507 PMCID: PMC3101707 DOI: 10.2174/156802611795429167] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 11/25/2010] [Indexed: 11/22/2022]
Abstract
African sleeping sickness is endemic in sub-Saharan Africa where the WHO estimates that 60 million people are at risk for the disease. Human African trypanosomiasis (HAT) is 100% fatal if untreated and the current drug therapies have significant limitations due to toxicity and difficult treatment regimes. No new chemical agents have been approved since eflornithine in 1990. The pentamidine analog DB289, which was in late stage clinical trials for the treatment of early stage HAT recently failed due to toxicity issues. A new protocol for the treatment of late-stage T. brucei gambiense that uses combination nifurtomox/eflornithine (NECT) was recently shown to have better safety and efficacy than eflornithine alone, while being easier to administer. This breakthrough represents the only new therapy for HAT since the approval of eflornithine. A number of research programs are on going to exploit the unusual biochemical pathways in the parasite to identify new targets for target based drug discovery programs. HTS efforts are also underway to discover new chemical entities through whole organism screening approaches. A number of inhibitors with anti-trypanosomal activity have been identified by both approaches, but none of the programs are yet at the stage of identifying a preclinical candidate. This dire situation underscores the need for continued effort to identify new chemical agents for the treatment of HAT.
Collapse
Affiliation(s)
- Robert T. Jacobs
- SCYNEXIS, Inc., Research Triangle Park, North Carolina 27709-2878
| | - Bakela Nare
- SCYNEXIS, Inc., Research Triangle Park, North Carolina 27709-2878
| | - Margaret A. Phillips
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, Texas 75390-9041
| |
Collapse
|
39
|
The kinetoplast duplication cycle in Trypanosoma brucei is orchestrated by cytoskeleton-mediated cell morphogenesis. Mol Cell Biol 2010; 31:1012-21. [PMID: 21173163 DOI: 10.1128/mcb.01176-10] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mitochondrial DNA of Trypanosoma brucei is organized in a complex structure called the kinetoplast. In this study, we define the complete kinetoplast duplication cycle in T. brucei based on three-dimensional reconstructions from serial-section electron micrographs. This structural model was enhanced by analyses of the replication process of DNA maxi- and minicircles. Novel insights were obtained about the earliest and latest stages of kinetoplast duplication. We show that kinetoplast S phase occurs concurrently with the repositioning of the new basal body from the anterior to the posterior side of the old flagellum. This emphasizes the role of basal body segregation in kinetoplast division and suggests a possible mechanism for driving the rotational movement of the kinetoplast during minicircle replication. Fluorescence in situ hybridization with minicircle- and maxicircle-specific probes showed that maxicircle DNA is stretched out between segregated minicircle networks, indicating that maxicircle segregation is a late event in the kinetoplast duplication cycle. This new view of the complexities of kinetoplast duplication emphasizes the dependencies between the dynamic remodelling of the cytoskeleton and the inheritance of the mitochondrial genome.
Collapse
|
40
|
Mitochondrial localization of the threonine peptidase PfHslV, a ClpQ ortholog in Plasmodium falciparum. Int J Parasitol 2010; 40:1517-23. [DOI: 10.1016/j.ijpara.2010.05.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 04/18/2010] [Accepted: 05/04/2010] [Indexed: 12/17/2022]
|
41
|
Fernández-Moya SM, Estévez AM. Posttranscriptional control and the role of RNA-binding proteins in gene regulation in trypanosomatid protozoan parasites. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:34-46. [PMID: 21956905 DOI: 10.1002/wrna.6] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Trypanosomatids are unicellular eukaryotes responsible for severe diseases in humans. They exhibit a number of remarkable biological phenomena, especially at the RNA level. During their life cycles, they alternate between a mammalian host and an insect vector and undergo profound biochemical and morphological transformations in order to adapt to the different environments they find within one or the other host species. These changes are orchestrated by specific gene expression programs. In contrast to other organisms, trypanosomatids do not regulate RNA polymerase II-dependent transcription initiation. Evidence so far indicates that the main control points in gene expression are mRNA degradation and translation. Recent studies have shown that RNA-binding proteins (RBPs) play a critical role in the developmental regulation of mRNA and protein abundance. RBPs seem to bind to specific subsets of mRNAs encoding functionally related proteins. These ribonucleoprotein complexes may represent posttranscriptional operons or regulons that are able to control the fate of multiple mRNAs simultaneously. We suggest that trypanosomatids transduce environmental signals into mRNA and protein abundance through posttranslational modification of RBPs.
Collapse
Affiliation(s)
- Sandra M Fernández-Moya
- Instituto de Parasitologia y Biomedicina Lopez-Neyra, CSIC, Avenida del Conocimiento, s/n, 18100 Armilla, Granada, Spain
| | | |
Collapse
|
42
|
Abstract
Helicases are ubiquitous enzymes found in all organisms that are necessary for all (or virtually all) aspects of nucleic acid metabolism. The Pif1 helicase family is a group of 5'-->3' directed, ATP-dependent, super family IB helicases found in nearly all eukaryotes. Here, we review the discovery, evolution, and what is currently known about these enzymes in Saccharomyces cerevisiae (ScPif1 and ScRrm3), Schizosaccharomyces pombe (SpPfh1), Trypanosoma brucei (TbPIF1, 2, 5, and 8), mice (mPif1), and humans (hPif1). Pif1 helicases variously affect telomeric, ribosomal, and mitochondrial DNA replication, as well as Okazaki fragment maturation, and in at least some cases affect these processes by using their helicase activity to disrupt stable nucleoprotein complexes. While the functions of these enzymes vary within and between organisms, it is evident that Pif1 family helicases are crucial for both nuclear and mitochondrial genome maintenance.
Collapse
Affiliation(s)
- Matthew L Bochman
- Department of Molecular Biology, Princeton University, 101 Lewis Thomas Laboratory, Washington Rd., Princeton, NJ 08544, USA
| | | | | |
Collapse
|
43
|
Gutiérrez B, Osorio L, Motta MCM, Huima-Byron T, Erdjument-Bromage H, Muñoz C, Sagua H, Mortara RA, Echeverría A, Araya JE, González J. Molecular characterization and intracellular distribution of the alpha 5 subunit of Trypanosoma cruzi 20S proteasome. Parasitol Int 2009; 58:367-74. [DOI: 10.1016/j.parint.2009.07.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 07/09/2009] [Accepted: 07/20/2009] [Indexed: 10/20/2022]
|
44
|
Abstract
In this issue, Liu et al. (2009) report that maxicircle DNA copy number in trypanosomes is regulated by proteolysis of a helicase; the complex kinetoplast DNA system yields a clear view of how mitochondrial DNA replication can be regulated.
Collapse
Affiliation(s)
- Michele M Klingbeil
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
| | | |
Collapse
|
45
|
Trypanosomes have six mitochondrial DNA helicases with one controlling kinetoplast maxicircle replication. Mol Cell 2009; 35:490-501. [PMID: 19646907 DOI: 10.1016/j.molcel.2009.07.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 05/19/2009] [Accepted: 07/14/2009] [Indexed: 11/23/2022]
Abstract
Kinetoplast DNA (kDNA), the trypanosome mitochondrial DNA, contains thousands of minicircles and dozens of maxicircles interlocked in a giant network. Remarkably, Trypanosoma brucei's genome encodes 8 PIF1-like helicases, 6 of which are mitochondrial. We now show that TbPIF2 is essential for maxicircle replication. Maxicircle abundance is controlled by TbPIF2 level, as RNAi of this helicase caused maxicircle loss, and its overexpression caused a 3- to 6-fold increase in maxicircle abundance. This regulation of maxicircle level is mediated by the TbHslVU protease. Previous experiments demonstrated that RNAi knockdown of TbHslVU dramatically increased abundance of minicircles and maxicircles, presumably because a positive regulator of their synthesis escaped proteolysis and allowed synthesis to continue. Here, we found that TbPIF2 level increases following RNAi of the protease. Therefore, this helicase is a TbHslVU substrate and an example of a positive regulator, thus providing a molecular mechanism for controlling maxicircle replication.
Collapse
|