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Kankanamge D, Tennakoon M, Karunarathne A, Gautam N. G protein gamma subunit, a hidden master regulator of GPCR signaling. J Biol Chem 2022; 298:102618. [PMID: 36272647 PMCID: PMC9678972 DOI: 10.1016/j.jbc.2022.102618] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 11/21/2022] Open
Abstract
Heterotrimeric G proteins (αβγ subunits) that are activated by G protein-coupled receptors (GPCRs) mediate the biological responses of eukaryotic cells to extracellular signals. The α subunits and the tightly bound βγ subunit complex of G proteins have been extensively studied and shown to control the activity of effector molecules. In contrast, the potential roles of the large family of γ subunits have been less studied. In this review, we focus on present knowledge about these proteins. Induced loss of individual γ subunit types in animal and plant models result in strikingly distinct phenotypes indicating that γ subtypes play important and specific roles. Consistent with these findings, downregulation or upregulation of particular γ subunit types result in various types of cancers. Clues about the mechanistic basis of γ subunit function have emerged from imaging the dynamic behavior of G protein subunits in living cells. This shows that in the basal state, G proteins are not constrained to the plasma membrane but shuttle between membranes and on receptor activation βγ complexes translocate reversibly to internal membranes. The translocation kinetics of βγ complexes varies widely and is determined by the membrane affinity of the associated γ subtype. On translocating, some βγ complexes act on effectors in internal membranes. The variation in translocation kinetics determines differential sensitivity and adaptation of cells to external signals. Membrane affinity of γ subunits is thus a parsimonious and elegant mechanism that controls information flow to internal cell membranes while modulating signaling responses.
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Affiliation(s)
- Dinesh Kankanamge
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Mithila Tennakoon
- Department of Chemistry, St Louis University, St Louis, Missouri, USA
| | | | - N Gautam
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; Department of Genetics, Washington University School of Medicine, St Louis, Missouri, USA.
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Delfino D, Rossetti DV, Martelli C, Inserra I, Vincenzoni F, Castagnola M, Urbani A, Scarpa S, Fuso A, Cavallaro RA, Desiderio C. Exploring the brain tissue proteome of TgCRND8 Alzheimer's Disease model mice under B vitamin deficient diet induced hyperhomocysteinemia by LC-MS top-down platform. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1124:165-172. [PMID: 31202182 DOI: 10.1016/j.jchromb.2019.06.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 05/28/2019] [Accepted: 06/04/2019] [Indexed: 01/23/2023]
Abstract
The multifactorial nature of Late Onset Alzheimer's Disease (LOAD), the AD form of major relevance on epidemiological and social aspects, has driven the original investigation by LC-MS and top-down proteomics approach of the protein repertoire of the brain tissue of TgCRND8 model mice fed with a diet deficient in B vitamins. The analysis of the acid-soluble fraction of brain tissue homogenates identified a list of proteins and peptides, proteoforms and PTMs. In order to disclose possible modulations, their relative quantification in wild type and AD model mice under both B vitamin deficient and control diets was performed. The levels of metallothionein III, guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2 and brain acid soluble protein 1 showed statistically significant alterations depending on genotype, diet or both effects, respectively. Particularly, metallothionein III exhibited increased levels in TgCRND8 mice under B vitamin deficient diet with respect to wild type mice under both diets. Brain acid soluble protein 1 showed the opposite, revealing decreased levels in all diet groups of AD model mice with respect to wild type mice in control diet. Lower levels of brain acid soluble protein 1 were also observed in wild type mice under deficiency of B vitamins. These results, besides contributing to increase the knowledge of AD at molecular level, give new suggestions for deeply investigating metallothionein III and brain acid soluble protein 1 in AD.
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Affiliation(s)
- Daniela Delfino
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Diana Valeria Rossetti
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia; Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italia
| | - Claudia Martelli
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Ilaria Inserra
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Federica Vincenzoni
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia; Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italia
| | - Massimo Castagnola
- Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Rome, Italy; Laboratorio di Proteomica e Metabonomica, IRCCS, Fondazione Santa Lucia, Roma, Italia
| | - Andrea Urbani
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia; Area Diagnostica di Laboratorio, Fondazione Policlinico Universitario Agostino Gemelli - IRCCS, Roma, Italy
| | - Sigfrido Scarpa
- Dipartimento di Chirurgia "P. Valdoni", Sapienza Università di Roma, Rome, Italy
| | - Andrea Fuso
- Dipartimento di Medicina Sperimentale, Sapienza Università di Roma, Rome, Italy
| | - Rosaria A Cavallaro
- Dipartimento di Chirurgia "P. Valdoni", Sapienza Università di Roma, Rome, Italy
| | - Claudia Desiderio
- Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Rome, Italy.
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Senarath K, Kankanamge D, Samaradivakara S, Ratnayake K, Tennakoon M, Karunarathne A. Regulation of G Protein βγ Signaling. Int Rev Cell Mol Biol 2018; 339:133-191. [PMID: 29776603 DOI: 10.1016/bs.ircmb.2018.02.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins) deliver external signals to the cell interior, upon activation by the external signal stimulated G protein-coupled receptors (GPCRs).While the activated GPCRs control several pathways independently, activated G proteins control the vast majority of cellular and physiological functions, ranging from vision to cardiovascular homeostasis. Activated GPCRs dissociate GαGDPβγ heterotrimer into GαGTP and free Gβγ. Earlier, GαGTP was recognized as the primary signal transducer of the pathway and Gβγ as a passive signaling modality that facilitates the activity of Gα. However, Gβγ later found to regulate more number of pathways than GαGTP does. Once liberated from the heterotrimer, free Gβγ interacts and activates a diverse range of signaling regulators including kinases, lipases, GTPases, and ion channels, and it does not require any posttranslation modifications. Gβγ family consists of 48 members, which show cell- and tissue-specific expressions, and recent reports show that cells employ the subtype diversity in Gβγ to achieve desired signaling outcomes. In addition to activated GPCRs, which induce free Gβγ generation and the rate of GTP hydrolysis in Gα, which sequester Gβγ in the heterotrimer, terminating Gβγ signaling, additional regulatory mechanisms exist to regulate Gβγ activity. In this chapter, we discuss structure and function, subtype diversity and its significance in signaling regulation, effector activation, regulatory mechanisms as well as the disease relevance of Gβγ in eukaryotes.
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Barbar A, Couture M, Sen SE, Béliveau C, Nisole A, Bipfubusa M, Cusson M. Cloning, expression and characterization of an insect geranylgeranyl diphosphate synthase from Choristoneura fumiferana. Insect Biochem Mol Biol 2013; 43:947-958. [PMID: 23907071 DOI: 10.1016/j.ibmb.2013.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/20/2013] [Accepted: 07/22/2013] [Indexed: 06/02/2023]
Abstract
Geranylgeranyl diphosphate synthase (GGPPS) catalyzes the condensation of the non-allylic diphosphate, isopentenyl diphosphate (IPP; C5), with allylic diphosphates to generate the C20 prenyl chain (GGPP) used for protein prenylation and diterpenoid biosynthesis. Here, we cloned the cDNA of a GGPPS from the spruce budworm, Choristoneura fumiferana, and characterized the corresponding recombinant protein (rCfGGPPS). As shown for other type-III GGPPSs, rCfGGPPS preferred farnesyl diphosphate (FPP; C15) over other allylic substrates for coupling with IPP. Unexpectedly, rCfGGPPS displayed inhibition by its FPP substrate at low IPP concentration, suggesting the existence of a mechanism that may regulate intracellular FPP pools. rCfGGPPS was also inhibited by its product, GGPP, in a competitive manner with respect to FPP, as reported for human and bovine brain GGPPSs. A homology model of CfGGPPS was prepared and compared to human and yeast GGPPSs. Consistent with its enzymological properties, CfGGPPS displayed a larger active site cavity that can accommodate the binding of FPP and GGPP in the region normally occupied by IPP and the allylic isoprenoid tail, and the binding of GGPP in an alternate orientation seen for GGPP binding to the human protein. To begin exploring the role of CfGGPPS in protein prenylation, its transcripts were quantified by qPCR in whole insects, along with those of other genes involved in this pathway. CfGGPPS was expressed throughout insect development and the abundance of its transcripts covaried with that of other prenylation-related genes. Our qPCR results suggest that geranylgeranylation is the predominant form of prenylation in whole C. fumiferana.
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Affiliation(s)
- Aline Barbar
- Département de biochimie, de microbiologie et de bio-informatique, Université Laval, Québec, QC G1V 0A6, Canada; Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., C.P. 10380, Succ. Sainte-Foy, Québec, QC G1V 4C7, Canada
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Abstract
G protein-gated inward rectifier K+ (GIRK) channels allow neurotransmitters, via G protein-coupled receptor stimulation, to control cellular electrical excitability. In cardiac and neuronal cells this control regulates heart rate and neural circuit activity. We present the 3.5 Å resolution crystal structure of the mammalian GIRK2 channel in complex with βγ G protein subunits, the central signaling complex that links G protein-coupled receptor stimulation to K+ channel activity. Short-range atomic and long-range electrostatic interactions stabilize four βγ G protein subunits at the interfaces between four K+ channel subunits, inducing a pre-open state of the channel. The pre-open state exhibits a conformation that is intermediate between the closed and constitutively active mutant, open conformations. The resultant structural picture is compatible with “membrane delimited” activation of GIRK channels by G proteins and the characteristic burst kinetics of channel gating. The structures also permit a conceptual understanding of how the signaling lipid PIP2 and intracellular Na+ ions participate in multi-ligand regulation of GIRK channels.
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Abstract
Protein farnesylation and geranylgeranylation, together referred to as prenylation, are lipid post-translational modifications that are required for the transforming activity of many oncogenic proteins, including some RAS family members. This observation prompted the development of inhibitors of farnesyltransferase (FT) and geranylgeranyl-transferase 1 (GGT1) as potential anticancer drugs. In this Review, we discuss the mechanisms by which FT and GGT1 inhibitors (FTIs and GGTIs, respectively) affect signal transduction pathways, cell cycle progression, proliferation and cell survival. In contrast to their preclinical efficacy, only a small subset of patients responds to FTIs. Identifying tumours that depend on farnesylation for survival remains a challenge, and strategies to overcome this are discussed. One GGTI has recently entered the clinic, and the safety and efficacy of GGTIs await results from clinical trials.
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Affiliation(s)
- Norbert Berndt
- Drug Discovery Department, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, Florida 33612, USA
| | - Andrew D. Hamilton
- University of Oxford, Vice-Chancellor’s Office, Wellington Square, Oxford OX1 2JD, UK
| | - Saïd M. Sebti
- Drug Discovery Department, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, Florida 33612, USA
- Departments of Oncologic Sciences and Molecular Medicine, University of South Florida, 12901 Bruce B. Downs Boulevard, Tampa, Florida 33612, USA
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Price CTD, Jones SC, Amundson KE, Kwaik YA. Host-mediated post-translational prenylation of novel dot/icm-translocated effectors of legionella pneumophila. Front Microbiol 2010; 1:131. [PMID: 21687755 PMCID: PMC3109360 DOI: 10.3389/fmicb.2010.00131] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Accepted: 11/01/2010] [Indexed: 11/17/2022] Open
Abstract
The Dot/Icm type IV translocated Ankyrin B (AnkB) effector of Legionella pneumophila is modified by the host prenylation machinery that anchors it into the outer leaflet of the Legionella-containing vacuole (LCV), which is essential for biological function of the effector in vitro and in vivo. Prenylation involves the covalent linkage of an isoprenoid lipid moiety to a C-terminal CaaX motif in eukaryotic proteins enabling their anchoring into membranes. We show here that the LCV harboring an ankB null mutant is decorated with prenylated proteins in a Dot/Icm-dependent manner, indicating that other LCV membrane-anchored proteins are prenylated. In silico analyses of four sequenced L. pneumophila genomes revealed the presence of eleven other genes that encode proteins with a C-terminal eukaryotic CaaX prenylation motif. Of these eleven designated Prenylated effectors of Legionella (Pel), seven are also found in L. pneumophila AA100. We show that six L. pneumophila AA100 Pel proteins exhibit distinct cellular localization when ectopically expressed in mammalian cells and this is dependent on action of the host prenylation machinery and the conserved cysteine residue of the CaaX motif. Although inhibition of the host prenylation machinery completely blocks intra-vacuolar proliferation of L. pneumophila, it only had a modest effect on intracellular trafficking of the LCV. Five of the Pel proteins are injected into human macrophages by the Dot/Icm type IV translocation system of L. pneumophila. Taken together, the Pel proteins are novel Dot/Icm-translocated effectors of L. pneumophila that are post-translationally modified by the host prenylation machinery, which enables their anchoring into cellular membranes, and the prenylated effectors contribute to evasion of lysosomal fusion by the LCV.
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Affiliation(s)
- Christopher T D Price
- Department of Microbiology and Immunology, College of Medicine, University of Louisville Louisville, KY, USA
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Affiliation(s)
- Uyen T T Nguyen
- Laboratory of Synthetic Protein Chemistry, The Rockefeller University, New York, NY 10065, USA
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Price CTD, Al-Quadan T, Santic M, Jones SC, Abu Kwaik Y. Exploitation of conserved eukaryotic host cell farnesylation machinery by an F-box effector of Legionella pneumophila. ACTA ACUST UNITED AC 2010; 207:1713-26. [PMID: 20660614 PMCID: PMC2916131 DOI: 10.1084/jem.20100771] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Farnesylation involves covalent linkage of eukaryotic proteins to a lipid moiety to anchor them into membranes, which is essential for the biological function of Ras and other proteins. A large cadre of bacterial effectors is injected into host cells by intravacuolar pathogens through elaborate type III–VII translocation machineries, and many of these effectors are incorporated into the pathogen-containing vacuolar membrane by unknown mechanisms. The Dot/Icm type IV secretion system of Legionella pneumophila injects into host cells the F-box effector Ankyrin B (AnkB), which functions as platforms for the docking of polyubiquitinated proteins to the Legionella-containing vacuole (LCV) to enable intravacuolar proliferation in macrophages and amoeba. We show that farnesylation of AnkB is indispensable for its anchoring to the cytosolic face of the LCV membrane, for its biological function within macrophages and Dictyostelium discoideum, and for intrapulmonary proliferation in mice. Remarkably, the protein farnesyltransferase, RCE-1 (Ras-converting enzyme-1), and isoprenyl cysteine carboxyl methyltransferase host farnesylation enzymes are recruited to the LCV in a Dot/Icm-dependent manner and are essential for the biological function of AnkB. In conclusion, this study shows novel localized recruitment of the host farnesylation machinery and its anchoring of an F-box effector to the LCV membrane, and this is essential for biological function in vitro and in vivo.
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Affiliation(s)
- Christopher T D Price
- Department of Microbiology and Immunology, School of Medicine and 2 Department of Biology, University of Louisville, Louisville, KY 40292, USA
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Brandt W, Bräuer L, Günnewich N, Kufka J, Rausch F, Schulze D, Schulze E, Weber R, Zakharova S, Wessjohann L. Molecular and structural basis of metabolic diversity mediated by prenyldiphosphate converting enzymes. Phytochemistry 2009; 70:1758-1775. [PMID: 19878958 DOI: 10.1016/j.phytochem.2009.09.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 08/31/2009] [Accepted: 09/01/2009] [Indexed: 05/28/2023]
Abstract
General thermodynamic calculations using the semiempiric PM3 method have led to the conclusion that prenyldiphosphate converting enzymes require at least one divalent metal cation for the activation and cleavage of the diphosphate-prenyl ester bond, or they must provide structural elements for the efficient stabilization of the intermediate prenyl cation. The most important common structural features, which guide the product specificity in both terpene synthases and aromatic prenyl transferases are aromatic amino acid side chains, which stabilize prenyl cations by cation-pi interactions. In the case of aromatic prenyl transferases, a proton abstraction from the phenolic hydroxyl group of the second substrate will enhance the electron density in the phenolic ortho-position at which initial prenylation of the aromatic compound usually occurs. A model of the structure of the integral transmembrane-bound aromatic prenyl transferase UbiA was developed, which currently represents the first structural insight into this group of prenylating enzymes with a fold different from most other aromatic prenyl transferases. Based on this model, the structure-activity relationships and mechanistic aspects of related proteins, for example those of Lithospermum erythrorhizon or the enzyme AuaA from Stigmatella aurantiaca involved in the aurachin biosynthesis, were elucidated. The high similarity of this group of aromatic prenyltransferases to 5-epi-aristolochene synthase is an indication of an evolutionary relationship with terpene synthases (cyclases). This is further supported by the conserved DxxxD motif found in both protein families. In contrast, there is no such relationship to the aromatic prenyl transferases with an ABBA-fold, such as NphB, or to any other known family of prenyl converting enzymes. Therefore, it is possible that these two groups might have different evolutionary ancestors.
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Affiliation(s)
- Wolfgang Brandt
- Leibniz Institute of Plant Biochemistry, Department of Bioorganic Chemistry, Halle (Saale), Germany.
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McIntire WE. Structural determinants involved in the formation and activation of G protein betagamma dimers. Neurosignals 2009; 17:82-99. [PMID: 19212142 DOI: 10.1159/000186692] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 05/13/2008] [Indexed: 01/08/2023] Open
Abstract
Heterotrimeric G proteins, composed of an alpha, beta and gamma subunit, represent one of the most important and dynamic families of signaling proteins. As a testament to the significance of G protein signaling, the hundreds of seven-transmembrane-spanning receptors that interact with G proteins are estimated to occupy 1-2% of the human genome. This broad diversity of receptors is echoed in the number of potential heterotrimer combinations that can arise from the 23 alpha subunit, 7 beta subunit and 12 gamma subunit isoforms that have been identified. The potential for such vast complexity implies that the receptor G protein interface is the site of much regulation. The historical model for the activation of a G protein holds that activated receptor catalyzes the exchange of GDP for GTP on the alpha subunit, inducing a conformational change that substantially lowers the affinity of alpha for betagamma. This decreased affinity enables dissociation of betagamma from alpha and receptor. The free form of betagamma is thought to activate effectors, until the hydrolysis of GTP by G alpha (aided by RGS proteins) allows the subunits to re-associate, effectively deactivating the G protein until another interaction with activated receptor.
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Affiliation(s)
- William E McIntire
- Department of Pharmacology, University of Virginia Health System, Charlottesville, VA 22908, USA.
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Davies BSJ, Yang SH, Farber E, Lee R, Buck SB, Andres DA, Spielmann HP, Agnew BJ, Tamanoi F, Fong LG, Young SG. Increasing the length of progerin's isoprenyl anchor does not worsen bone disease or survival in mice with Hutchinson-Gilford progeria syndrome. J Lipid Res 2008; 50:126-34. [PMID: 18757838 DOI: 10.1194/jlr.m800424-jlr200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is caused by the synthesis of a truncated prelamin A, commonly called progerin, that contains a carboxyl-terminal farnesyl lipid anchor. The farnesyl lipid anchor helps to target progerin to membrane surfaces at the nuclear rim, where it disrupts the integrity of the nuclear lamina and causes misshapen nuclei. Several lines of evidence have suggested that progerin's farnesyl lipid anchor is crucial for the emergence of disease phenotypes. Because a geranylgeranyl lipid is approximately 45-fold more potent than a farnesyl lipid in anchoring proteins to lipid membranes, we hypothesized that a geranylgeranylated version of progerin might be more potent in eliciting disease phenotypes. To test this hypothesis, we used gene targeting to create mice expressing geranylgeranylated progerin (Lmna(ggHG/+)). We then compared Lmna(ggHG/+) mice, side-by-side, with otherwise identical mice expressing farnesylated progerin (Lmna(HG/+)). Geranylgeranylation of progerin in Lmna(ggHG/+) cells and farnesylation of progerin in Lmna(HG/+) cells was confirmed by metabolic labeling. Contrary to our expectations, Lmna(ggHG/+) mice survived longer than Lmna(HG/+) mice. The Lmna(ggHG/+) mice also exhibited milder bone disease. The steady-state levels of progerin, relative to lamin C, were lower in Lmna(ggHG/+) mice than in Lmna(HG/+) mice, providing a potential explanation for the milder disease in Lmna(ggHG/+) mice.
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Affiliation(s)
- Brandon S J Davies
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Affiliation(s)
- R G Krishna
- Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston
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Abstract
Prenylated proteins undergo a series of post-translational modifications, including prenylation, proteolysis, and methylation. Collectively, these modifications generate a prenylcysteine methylester at the carboxyl terminus and modulate protein targeting and function. Prenylcysteine methylation is the only reversible step in this series of modifications. However, prenylcysteine alpha-carboxyl methylesterase (PCME) activity has not been described in plants. We have detected a specific PCME activity in Arabidopsis thaliana membranes that discriminates between biologically relevant and irrelevant prenylcysteine methylester substrates. Furthermore, we have identified an Arabidopsis gene (At5g15860) that encodes measurable PCME activity in recombinant yeast cells with greater specificity for biologically relevant prenylcysteine methylesters than the activity found in Arabidopsis membranes. These results suggest that specific and non-specific esterases catalyze the demethylation of prenylcysteine methylesters in Arabidopsis membranes. Our findings are discussed in the context of prenylcysteine methylation/demethylation as a potential regulatory mechanism for membrane association and function of prenylated proteins in Arabidopsis.
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Affiliation(s)
- Angela K Deem
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202-5132, USA
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Benetka W, Koranda M, Eisenhaber F. Protein Prenylation: An (Almost) Comprehensive Overview on Discovery History, Enzymology, and Significance in Physiology and Disease. Monatsh Chem 2006; 137:1241-81. [DOI: 10.1007/s00706-006-0534-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Abstract
Hepatitis delta virus (HDV) is an important cause of acute and chronic liver disease. Current medical therapies are unable to effectively eradicate HDV infections. Research into the molecular virology of the HDV life cycle has revealed a fascinating collection of biology. These insights are now beginning to be translated into new potential treatment strategies. For example, an essential step in the virus assembly process involves the post-translational lipid modification of a specific HDV protein, namely prenylation of large delta antigen. Preventing prenylation abolishes virus particle formation. Drugs capable of specifically inhibiting prenylation have been developed for use in humans. These agents represent a new class of antiviral agents, with HDV as a first target. Here, a brief review of the HDV life cycle emphasizing the role of prenylation is presented along with implications for drug development and therapy.
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Affiliation(s)
- J S Glenn
- Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Palo Alto, CA 94305-5187, USA.
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Akgoz M, Kalyanaraman V, Gautam N. G protein betagamma complex translocation from plasma membrane to Golgi complex is influenced by receptor gamma subunit interaction. Cell Signal 2006; 18:1758-68. [PMID: 16517125 PMCID: PMC2230546 DOI: 10.1016/j.cellsig.2006.01.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 01/23/2006] [Accepted: 01/24/2006] [Indexed: 10/24/2022]
Abstract
On activation of a receptor the G protein betagamma complex translocates away from the receptor on the plasma membrane to the Golgi complex. The rate of translocation is influenced by the type of gamma subunit associated with the G protein. Complementary approaches--imaging living cells expressing fluorescent protein tagged G proteins and assaying reconstituted receptors and G proteins in vitro--were used to identify mechanisms at the basis of the translocation process. Translocation of Gbetagamma containing mutant gamma subunits with altered prenyl moieties showed that the differences in the prenyl moieties were not sufficient to explain the differential effects of geranylgeranylated gamma5 and farnesylated gamma11 on the translocation process. The translocation properties of Gbetagamma were altered dramatically by mutating the C terminal tail region of the gamma subunit. The translocation characteristics of these mutants suggest that after receptor activation, Gbetagamma retains contact with a receptor through the gamma subunit C terminal domain and that differential interaction of the activated receptor with this domain controls Gbetagamma translocation from the plasma membrane.
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Affiliation(s)
- Muslum Akgoz
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, United States
| | - Vani Kalyanaraman
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, United States
| | - N. Gautam
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, United States
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, United States
- Corresponding author. Box 8054, Washington University School Medicine, St. Louis, MO 63110. Tel.: +1 314 362 8568; fax: +1 314 362 8571. E-mail address: (N. Gautam)
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Johnson CD, Chary SN, Chernoff EA, Zeng Q, Running MP, Crowell DN. Protein geranylgeranyltransferase I is involved in specific aspects of abscisic acid and auxin signaling in Arabidopsis. Plant Physiol 2005; 139:722-33. [PMID: 16183844 PMCID: PMC1255991 DOI: 10.1104/pp.105.065045] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Arabidopsis (Arabidopsis thaliana) mutants lacking a functional ERA1 gene, which encodes the beta-subunit of protein farnesyltransferase (PFT), exhibit pleiotropic effects that establish roles for protein prenylation in abscisic acid (ABA) signaling and meristem development. Here, we report the effects of T-DNA insertion mutations in the Arabidopsis GGB gene, which encodes the beta-subunit of protein geranylgeranyltransferase type I (PGGT I). Stomatal apertures of ggb plants were smaller than those of wild-type plants at all concentrations of ABA tested, suggesting that PGGT I negatively regulates ABA signaling in guard cells. However, germination of ggb seeds in response to ABA was similar to the wild type. Lateral root formation in response to exogenous auxin was increased in ggb seedlings compared to the wild type, but no change in auxin inhibition of primary root growth was observed, suggesting that PGGT I is specifically involved in negative regulation of auxin-induced lateral root initiation. Unlike era1 mutants, ggb mutants exhibited no obvious developmental phenotypes. However, era1 ggb double mutants exhibited more severe developmental phenotypes than era1 mutants and were indistinguishable from plp mutants lacking the shared alpha-subunit of PFT and PGGT I. Furthermore, overexpression of GGB in transgenic era1 plants partially suppressed the era1 phenotype, suggesting that the relatively weak phenotype of era1 plants is due to partial redundancy between PFT and PGGT I. These results are discussed in the context of Arabidopsis proteins that are putative substrates of PGGT I.
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Affiliation(s)
- Cynthia D Johnson
- Department of Biology, Indiana University-Purdue University, Indianapolis, 46202-5132, USA
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21
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Glenn MP, Chang SY, Hucke O, Verlinde CLMJ, Rivas K, Hornéy C, Yokoyama K, Buckner FS, Pendyala PR, Chakrabarti D, Gelb M, Van Voorhis WC, Sebti SM, Hamilton AD. Structurally Simple Farnesyltransferase Inhibitors Arrest the Growth of Malaria Parasites. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200500674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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22
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Glenn MP, Chang SY, Hucke O, Verlinde CLMJ, Rivas K, Hornéy C, Yokoyama K, Buckner FS, Pendyala PR, Chakrabarti D, Gelb M, Van Voorhis WC, Sebti SM, Hamilton AD. Structurally Simple Farnesyltransferase Inhibitors Arrest the Growth of Malaria Parasites. Angew Chem Int Ed Engl 2005; 44:4903-6. [PMID: 16007716 DOI: 10.1002/anie.200500674] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Matthew P Glenn
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, CT 06511, USA
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23
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Rowinsky EK, Patnaik A. The development of protein farnesyltransferase and other ras-directed therapeutics for malignant diseases. ACTA ACUST UNITED AC 2005. [DOI: 10.1517/14728214.5.2.161] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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24
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Abstract
Heterotrimeric G proteins interact with receptors and effectors at the membrane-cytoplasm interface. Structures of soluble forms have not revealed how they interact with membranes. We have used electron crystallography to determine the structure in ice of a helical array of the photoreceptor G protein, transducin, bound to the surface of a tubular lipid bilayer. The protein binds to the membrane with a very small area of contact, restricted to two points, between the surface of the protein and the surface of the lipids. Fitting the x-ray structure into the membrane-bound structure reveals one membrane contact near the lipidated Ggamma C terminus and Galpha N terminus, and another near the Galpha C terminus. The narrowness of the tethers to the lipid bilayer provides flexibility for the protein to adopt multiple orientations on the membrane, and leaves most of the G protein surface area available for protein-protein interactions.
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Affiliation(s)
- Zhixian Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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25
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Hamilton MH, Cook LA, McRackan TR, Schey KL, Hildebrandt JD. Gamma 2 subunit of G protein heterotrimer is an N-end rule ubiquitylation substrate. Proc Natl Acad Sci U S A 2003; 100:5081-6. [PMID: 12700354 PMCID: PMC154301 DOI: 10.1073/pnas.0831228100] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterotrimeric G proteins transduce signals from activated transmembrane G protein-coupled receptors to appropriate downstream effectors within cells. Signaling specificity is achieved in part by the specific alpha, beta, and gamma subunits that compose a given heterotrimer. Additional structural and functional diversity in these subunits is generated at the level of posttranslational modification, offering alternate regulatory mechanisms for G protein signaling. Presented here is the identification of a variant of the gamma(2) subunit of G protein heterotrimer purified from bovine brain and the demonstration that this RDTASIA gamma(2) variant, containing unique amino acid sequence at its N terminus, is a substrate for ubiquitylation and degradation via the N-end rule pathway. Although N-end-dependent degradation has been shown to have important functions in peptide import, chromosome segregation, angiogenesis, and cardiovascular development, the identification of cellular substrates in mammalian systems has remained elusive. The isolation of RDTASIA gamma(2) from a native tissue represents identification of a mammalian N-end rule substrate from a physiological source, and elucidates a mechanism for the targeting of G protein gamma subunits for ubiquitylation and degradation.
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Affiliation(s)
- Maria H Hamilton
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425, USA
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26
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Gelb MH, Van Voorhis WC, Buckner FS, Yokoyama K, Eastman R, Carpenter EP, Panethymitaki C, Brown KA, Smith DF. Protein farnesyl and N-myristoyl transferases: piggy-back medicinal chemistry targets for the development of antitrypanosomatid and antimalarial therapeutics. Mol Biochem Parasitol 2003; 126:155-63. [PMID: 12615314 DOI: 10.1016/s0166-6851(02)00282-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To accelerate progress in the development of therapeutics for protozoan parasitic diseases, we are studying enzymes active in co- and post-translational protein modification that are already the focus of drug development in other eukaryotic systems. Inhibitors of the protein farnesyltransferases (PFT) are well-established antitumour agents of low cytotoxicity and known pharmokinetic properties, while inhibitors of N-myristoyl transferase show both selectivity and specificity in the treatment of fungal infections. Here, we summarise the current evidence that supports the targeting of these ubiquitous eukaryotic enzymes for drug development against trypanosomatid infections and malaria.
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Affiliation(s)
- Michael H Gelb
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA.
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27
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Kale TA, Raab C, Yu N, Aquino E, Dean DC, Distefano MD. Synthesis of high specific activity 35S-labelled N-methanesulfonyl farnesylcysteine and a photoactive analog. J Labelled Comp Radiopharm 2003. [DOI: 10.1002/jlcr.638] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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28
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Narasimha Chary S, Bultema RL, Packard CE, Crowell DN. Prenylcysteine alpha-carboxyl methyltransferase expression and function in Arabidopsis thaliana. Plant J 2002; 32:735-747. [PMID: 12472689 DOI: 10.1046/j.1365-313x.2002.01463.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Farnesylated proteins undergo a series of post-translational modifications, including carboxyl terminal isoprenylation, proteolysis, and methylation. In Arabidopsis thaliana, protein farnesylation has been shown to be necessary for negative regulation of ABA signaling. However, the role of post-isoprenylation protein processing in ABA signal transduction has not been described. Here, we show that the A. thaliana genome contains two distinct genes on chromosome V, AtSTE14A and AtSTE14B, which encode functional prenylcysteine alpha-carboxyl methyltransferases. AtSTE14B encodes a methyltransferase with lower apparent Kms for prenylcysteine substrates and higher specific activities than the previously described AtSTE14A-encoded methyltransferase. Furthermore, whereas AtSTE14A transcription is restricted to root and shoot tips, young leaves, and vascular tissue, AtSTE14B transcription is observed in all organs except hypocotyls and petioles. Pharmacological inhibitors of prenylcysteine alpha-carboxyl methyltransferase activity cause increased ABA sensitivity, seed dormancy, and stomatal closure, consistent with the hypothesis that prenylcysteine alpha-carboxyl methylation is necessary for negative regulation of ABA signaling. These results suggest that carboxyl methylation, which is a reversible and potentially regulated step in the processing, targeting, and function of isoprenylated plant proteins, may be an important biochemical target for introducing altered ABA sensitivity and drought tolerance into plants.
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Affiliation(s)
- S Narasimha Chary
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, 46202, USA
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29
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Chakrabarti D, Da Silva T, Barger J, Paquette S, Patel H, Patterson S, Allen CM. Protein farnesyltransferase and protein prenylation in Plasmodium falciparum. J Biol Chem 2002; 277:42066-73. [PMID: 12194969 DOI: 10.1074/jbc.m202860200] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Comparison of the malaria parasite and mammalian protein prenyltransferases and their cellular substrates is important for establishing this enzyme as a target for developing antimalarial agents. Nineteen heptapeptides differing only in their carboxyl-terminal amino acid were tested as alternative substrates of partially purified Plasmodium falciparum protein farnesyltransferase. Only NRSCAIM and NRSCAIQ serve as substrates, with NRSCAIM being the best. Peptidomimetics, FTI-276 and GGTI-287, inhibit the transferase with IC(50) values of 1 and 32 nm, respectively. Incubation of P. falciparum-infected erythrocytes with [(3)H]farnesol labels 50- and 22-28-kDa proteins, whereas [(3)H]geranylgeraniol labels only 22-28-kDa proteins. The 50-kDa protein is shown to be farnesylated, whereas the 22-28-kDa proteins are geranylgeranylated, irrespective of the labeling prenol. Protein labeling is inhibited more than 50% by either 5 microm FTI-277 or GGTI-298. The same concentration of inhibitors also inhibits parasite growth from the ring stage by 50%, decreases expression of prenylated proteins as measured with prenyl-specific antibody, and inhibits parasite differentiation beyond the trophozoite stage. Furthermore, differentiation specific prenylation of P. falciparum proteins is demonstrated. Protein labeling is detected predominantly during the trophozoite to schizont and schizont to ring transitions. These results demonstrate unique properties of protein prenylation in P. falciparum: a limited specificity of the farnesyltransferase for peptide substrates compared with mammalian enzymes, the ability to use farnesol to label both farnesyl and geranylgeranyl moieties on proteins, differentiation specific protein prenylation, and the ability of peptidomimetic prenyltransferase inhibitors to block parasite differentiation.
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Affiliation(s)
- Debopam Chakrabarti
- Department of Molecular Biology and Microbiology, University of Central Florida, Orlando 32816, USA
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30
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Fogg VC, Azpiazu I, Linder ME, Smrcka A, Scarlata S, Gautam N. Role of the gamma subunit prenyl moiety in G protein beta gamma complex interaction with phospholipase Cbeta. J Biol Chem 2001; 276:41797-802. [PMID: 11546822 DOI: 10.1074/jbc.m107661200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The G protein betagamma complex regulates a wide range of effectors, including the phospholipase Cbeta isozymes (PLCbetas). Prenyl modification of the gamma subunit is necessary for this activity. Evidence presented here supports a direct interaction between the G protein gamma subunit prenyl group and PLCbeta isozymes. A geranylgeranylated peptide corresponding to the C-terminal region of the gamma subunit type, gamma2, strongly inhibits stimulation of PLCbeta2 and PLCbeta3 activity by the betagamma complex. This effect is specific because the same peptide has no effect on stimulation of PLCbeta by an alpha subunit type, alphaq. Prenylation of the gamma peptide is required for its inhibitory effect. When interaction of prenylated gamma subunit peptide to fluorophore-tagged PLCbeta2 was examined by fluorescence spectroscopy, prenylated but not unprenylated peptide increased PLCbeta2 fluorescence emission energy, indicating direct binding of the prenyl moiety to PLCbeta. In addition, fluorescence resonance energy transfer was detected between fluorophore tagged PLCbeta and wild type betagamma complex but not an unprenylated mutant betagamma complex. We conclude that a major function of the gamma subunit prenyl group is to facilitate direct protein-protein interaction between the betagamma complex and an effector, phospholipase Cbeta.
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Affiliation(s)
- V C Fogg
- Departments of Anesthesiology, Genetics, and Cell Biology & Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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31
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Abstract
Bovine brain G(o)alpha was specifically palmitoylated in vitro. The apparent dissociation constant for depalmitoylated G(o)alpha (dG(o)alpha) was 0.273 microM, while that for palmitoylated G(o)alpha (pG(o)alpha) was 5.77 nM. The dissociation rate constant (K(21)) and dissociation half-life for dG(o)alpha were 8.4x10(-4) min and 825 min respectively, while no significant dissociation of pG(o)alpha was detected. The limiting membrane insertion pressures for pG(o)alpha and dG(o)alpha were 44.4 mN/m and 41.3 mN/m respectively. These data suggested that palmitoylation facilitated the membrane association of G(o)alpha. Conformational changes of dG(o)alpha and pG(o)alpha detected by monitoring fluorescence spectra and fluorescence quenching were significantly different after they were associated with the membrane. It was suggested that conformational changes of G(o)alpha upon membrane association might be related to regulation of G(o)alpha signaling by palmitoylation.
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Affiliation(s)
- S Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, PR China
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32
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Baron R, Fourcade E, Lajoie-Mazenc I, Allal C, Couderc B, Barbaras R, Favre G, Faye JC, Pradines A. RhoB prenylation is driven by the three carboxyl-terminal amino acids of the protein: evidenced in vivo by an anti-farnesyl cysteine antibody. Proc Natl Acad Sci U S A 2000; 97:11626-31. [PMID: 11027361 PMCID: PMC17251 DOI: 10.1073/pnas.97.21.11626] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein isoprenylation is a lipid posttranslational modification required for the function of many proteins that share a carboxyl-terminal CAAX motif. The X residue determines which isoprenoid will be added to the cysteine. When X is a methionine or serine, the farnesyl-transferase transfers a farnesyl, and when X is a leucine or isoleucine, the geranygeranyl-transferase I, a geranylgeranyl group. But despite its CKVL motif, RhoB was reported to be both geranylgeranylated and farnesylated. Thus, the determinants of RhoB prenylation appear more complex than initially thought. To determine the role of RhoB CAAX motif, we designed RhoB mutants with modified CAAX sequence expressed in baculovirus-infected insect cells. We demonstrated that RhoB was prenylated as a function of the three terminal amino acids, i.e., RhoB bearing the CAIM motif of lamin B or CLLL motif of Rap1A was farnesylated or geranylgeranylated, respectively. Next, we produced a specific polyclonal antibody against farnesyl cysteine methyl ester allowing prenylation analysis avoiding the metabolic labeling restrictions. We confirmed that the unique modification of the RhoB CAAX box was sufficient to direct the RhoB distinct prenylation in mammalian cells and, inversely, that a RhoA-CKVL chimera could be alternatively prenylated. Moreover, the immunoprecipitation of endogenous RhoB from cells with the anti-farnesyl cysteine antibody suggested that wild-type RhoB is farnesylated in vivo. Taken together, our results demonstrated that the three last carboxyl amino acids are the main determinants for RhoB prenylation and described an anti-farnesyl cysteine antibody as a useful tool for understanding the cellular control of protein farnesylation.
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Affiliation(s)
- R Baron
- Endocrinologie et Communications Cellulaires Institut National de la Santé et de la Recherche Médicale Unité 397, Toulouse, France
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33
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Abstract
Lovastatin prevents isoprene synthesis thereby affecting the structural organization of proteins involved in protein transport and secretion. Lovastatin at 1 microM decreases CCK 8 secretion by over 50% in WE cells and in CCK 8 expressing AtT20 cells. At 10 microM CCK 8 secretion was inhibited by two thirds and at 100 microM, cytotoxic effects were observed in both cell types. Addition of mevalonate does not restore CCK secretion and stimulation of secretion by forskolin is also partially inhibited. Cellular content of CCK 8 and pro-CCK were not altered in either of these cell lines except at 100 microM lovastatin. Our results clearly demonstrate that lovastatin at 1 microM strongly inhibits CCK 8 secretion at multiple levels while having little or no effect on its synthesis. This effect on secretion may be partly responsible for the adverse gastrointestinal side effects of lovastatin in patients.
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Affiliation(s)
- D Vishnuvardhan
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
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34
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Seo DW, Moon HI, Han JW, Hong SY, Lee HY, Kim S, Paik WK, Lee HW. An endogenous proteinacious inhibitor in porcine liver for S-adenosyl-L-methionine dependent methylation reactions: identification as oligosaccharide-linked acyl carrier protein. Int J Biochem Cell Biol 2000; 32:455-64. [PMID: 10762071 DOI: 10.1016/s1357-2725(99)00144-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A proteinacious inhibitor of S-adenosyl-L-methionine (AdoMet)-dependent transmethylation reactions was purified to homogeneity from porcine liver by size exclusion chromatography and FPLC. The molecular weight of the inhibitor was 12,222 Da. A 7400 Da polypeptide fragment of the purified inhibitor was sequenced by matrix-associated laser desorption ionization; time-of-flight MS, and was found to be identical with the known sequence of spinach acyl carrier protein (ACP). Although the remainder of the molecule was not clearly defined, 1H and H-H correlation of spectroscopy (COSY) NMR analysis revealed the presence of an oligosaccharide with alpha-glycosidic linkage. The purified oligosaccharide-linked ACP inhibited several AdoMet-dependent transmethylation reactions such as protein methylase I and II. S-farnesylcysteine O-methyltransferase, DNA methyltransferase and phospholipid methyltransferase. Protein methylase II was inhibited with a Ki value of 2.4 x 10(-3) M in a mixed inhibition pattern, whereas a well-known competitive product inhibitor S-adenosyl-L-homocysteine (AdoHcy) had Ki value of 6.3 x 10(-6) M. Commercially available active ACP fragments (65-74) and ACP from Escherichia coli had less inhibitory activity toward S-farnesylcysteine O-methyltransferase than the purified inhibitor. The biological significance of this oligosaccharide-linked ACP which has two seemingly unrelated functions (inhibitor for transmethylation and fatty acid biosynthesis) remains to be elucidated.
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Affiliation(s)
- D W Seo
- Department of Genetic Engineering, College of Life Science and Natural Resources, Sungkyunkwan University, Suwon, South Korea
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Whitten ME, Yokoyama K, Schieltz D, Ghomashchi F, Lam D, Yates JR, Palczewski K, Gelb MH. Structural analysis of protein prenyl groups and associated C-terminal modifications. Methods Enzymol 2000; 316:436-51. [PMID: 10800693 PMCID: PMC1435690 DOI: 10.1016/s0076-6879(00)16741-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- M E Whitten
- Department of Chemistry, University of Washington, Seattle 98195, USA
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Abstract
Ras proteins are guanine nucleotide-binding proteins that play pivotal roles in the control of normal and transformed cell growth and are among the most intensively studied proteins of the past decade. After stimulation by various growth factors and cytokines, Ras activates several downstream effectors, including the Raf-1/mitogen-activated protein kinase pathway and the Rac/Rho pathway. In approximately 30% of human cancers, including a substantial proportion of pancreatic and colon adenocarcinomas, mutated ras genes produce mutated proteins that remain locked in an active state, thereby relaying uncontrolled proliferative signals. Ras undergoes several posttranslational modifications that facilitate its attachment to the inner surface of the plasma membrane. The first-and most critical-modification is the addition of a farnesyl isoprenoid moiety in a reaction catalyzed by the enzyme protein farnesyltransferase (FTase). It follows that inhibiting FTase would prevent Ras from maturing into its biologically active form, and FTase is of considerable interest as a potential therapeutic target. Different classes of FTase inhibitors have been identified that block farnesylation of Ras, reverse Ras-mediated cell transformation in human cell lines, and inhibit the growth of human tumor cells in nude mice. In transgenic mice with established tumors, FTase inhibitors cause regression in some tumors, which appears to be mediated through both apoptosis and cell cycle regulation. FTase inhibitors have been well tolerated in animal studies and do not produce the generalized cytotoxic effects in normal tissues that are a major limitation of most conventional anticancer agents. There are ongoing clinical evaluations of FTase inhibitors to determine the feasibility of administering them on dose schedules like those that portend optimal therapeutic indices in preclinical studies. Because of the unique biologic aspects of FTase, designing disease-directed phase II and III evaluations of their effectiveness presents formidable challenges.
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Affiliation(s)
- E K Rowinsky
- Institute for Drug Development, Cancer Therapy and Research Center, San Antonio, TX 78229-3272, USA.
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37
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Abstract
For the study of biological phenomena influenced by the R- and N-Ras proteins, characteristic peptides which embody the correct lipid modifications of their parent proteins (palmitoyl thioesters, geranylgeranyl thioethers, and farnesyl thioethers), as well as analogues thereof, may serve as efficient tools. For the construction of such acid- and base labile peptide conjugates the allyl ester was developed as C-terminal protecting group. Allyl esters are cleaved selectively and in high yields from lipidated peptides by Pd(0)-mediated allyl transfer to accepting N- or C-nucleophiles like morpholine and N,N'-dimethylbarbituric acid. This protecting group technique formed the key step in the synthesis of the characteristic S-palmitoylated and S-isoprenylated C-terminus of human R-Ras and human N-Ras proteins, as well as several analogues thereof. Deprotections are so mild that no undesired side reactions of the lipid conjugates are observed.
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Affiliation(s)
- T Schmittberger
- Universität Karlsruhe, Institut für Organische Chemie, Karlsruhe, Germany
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Ohto C, Ishida C, Nakane H, Muramatsu M, Nishino T, Obata S. A thermophilic cyanobacterium Synechococcus elongatus has three different Class I prenyltransferase genes. Plant Mol Biol 1999; 40:307-21. [PMID: 10412909 DOI: 10.1023/a:1006295705142] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Prenyltransferases (prenyl diphosphate synthases), which are a broad group of enzymes that catalyze the consecutive condensation of homoallylic diphosphate of isopentenyl diphosphates (IPP, C5) with allylic diphosphates to synthesize prenyl diphosphates of various chain lengths, have highly conserved regions in their amino acid sequences. Based on the above information, three prenyltransferase homologue genes were cloned from a thermophilic cyanobacterium, Synechococcus elongatus. Through analyses of the reaction products of the enzymes encoded by these genes, it was revealed that one encodes a thermolabile geranylgeranyl (C20) diphosphate synthase, another encodes a farnesyl (C15) diphosphate synthase whose optimal reaction temperature is 60 degrees C, and the third one encodes a prenyltransferase whose optimal reaction temperature is 75 degrees C. The last enzyme could catalyze the synthesis of five prenyl diphosphates of farnesyl, geranylgeranyl, geranylfarnesyl (C25), hexaprenyl (C30), and heptaprenyl (C35) diphosphates from dimethylallyl (C5) diphosphate, geranyl (C10) diphosphate, or farnesyl diphosphate as the allylic substrates. The product specificity of this novel kind of enzyme varied according to the ratio of the allylic and homoallylic substrates. The situations of these three S. elongatus enzymes in a phylogenetic tree of prenyltransferases are discussed in comparison with a mesophilic cyanobacterium of Synechocystis PCC6803, whose complete genome has been reported by Kaneko et al. (1996).
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Affiliation(s)
- C Ohto
- Bio Research Laboratory, Toyota Motor Corporation, Toyota, Toyota, Japan
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39
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Abstract
Heterotrimeric signal-transducing G proteins are organized at the inner surface of the plasma membrane, where they are positioned to interact with membrane-spanning receptors and appropriate effectors. G proteins are activated when they bind GTP and inactivated when they hydrolyze the nucleotide to GDP. However, the topological fate of activated G protein alpha subunits is disputed. One model declares that depalmitoylation of alpha, which accompanies activation by a receptor, promotes release of the protein into the cytoplasm. Our data suggest that activation of G protein alpha subunits causes them to concentrate in subdomains of the plasma membrane but not to be released from the membrane. Furthermore, alpha subunits remained bound to the membrane when they were activated with guanosine 5'-(3-O-thio)triphosphate and depalmitoylated with an acyl protein thioesterase. Limitation of alpha subunits to the plasma membrane obviously restricts their mobility and may contribute to the efficiency and specificity of signaling.
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Affiliation(s)
- C Huang
- University of Texas Southwestern Medical Center, Department of Pharmacology, 5323 Harry Hines Boulevard, Dallas, TX 75235-9041, USA
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40
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Robbins SM, Hollenberg MD. Chapter 11 Plasma Membrane-Localized Signal Transduction. Current Topics in Membranes 1999. [DOI: 10.1016/s0070-2161(08)61049-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Yokoyama K, Trobridge P, Buckner FS, Van Voorhis WC, Stuart KD, Gelb MH. Protein farnesyltransferase from Trypanosoma brucei. A heterodimer of 61- and 65-kda subunits as a new target for antiparasite therapeutics. J Biol Chem 1998; 273:26497-505. [PMID: 9756885 DOI: 10.1074/jbc.273.41.26497] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously shown that protein prenylation occurs in the Trypanosomatids Trypanosoma brucei (T. brucei), Trypanosoma cruzi, and Leishmania mexicana and that protein farnesyltransferase (PFT) activity can be detected in cytosolic extracts of insect (procyclic) form T. brucei. A PFT that transfers the farnesyl group from farnesyl pyrophosphate to a cysteine that is 4 residues upstream of the C terminus of the Ras GTP-binding protein RAS1-CVIM has now been purified 60,000-fold to near homogeneity from procyclic T. brucei. By screening a mixture of hexapeptides SSCALX (X is 20 different amino acids), it was found that SSCALM binds to T. brucei PFT with sub-micromolar affinity, and affinity chromatography using this peptide was a key step in the purification of this enzyme. On SDS-polyacrylamide gel electrophoresis, the enzyme migrates as a pair of bands with apparent molecular masses of 61 and 65 kDa, and thus its subunits are approximately 30% larger than those of the mammalian homolog. The 61-kDa band was identified as the putative beta-subunit by photoaffinity labeling with a 32P-labeled analog of farnesyl pyrophosphate. Mimetics of the C-terminal tetrapeptide of prenyl acceptors have been previously shown to inhibit mammalian PFT, and these compounds also inhibit T. brucei PFT with affinities in the nanomolar to micromolar range, although the structure-activity relationship is very different for parasite versus mammalian enzyme. Unlike mammalian cells, the growth of bloodstream T. brucei is completely inhibited by low micromolar concentrations of two of the PFT inhibitors, and these compounds also block protein farnesylation in cultured parasites. These compounds also potently block the growth of the intracellular (amastigote) form of T. cruzi grown in fibroblast host cells. The results suggest that protein farnesylation is a target for the development of anti-trypanosomatid chemotherapeutics.
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Affiliation(s)
- K Yokoyama
- Departments of Chemistry and Biochemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700, USA
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Crowell DN, Sen SE, Randall SK. Prenylcysteine alpha-carboxyl methyltransferase in suspension-cultured tobacco cells. Plant Physiol 1998; 118:115-23. [PMID: 9733531 PMCID: PMC34848 DOI: 10.1104/pp.118.1.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/1998] [Accepted: 05/23/1998] [Indexed: 05/19/2023]
Abstract
Isoprenylation is a posttranslational modification that is believed to be necessary, but not sufficient, for the efficient association of numerous eukaryotic cell proteins with membranes. Additional modifications have been shown to be required for proper intracellular targeting and function of certain isoprenylated proteins in mammalian and yeast cells. Although protein isoprenylation has been demonstrated in plants, postisoprenylation processing of plant proteins has not been described. Here we demonstrate that cultured tobacco (Nicotiana tabacum cv Bright Yellow-2) cells contain farnesylcysteine and geranylgeranylcysteine alpha-carboxyl methyltransferase activities with apparent Michaelis constants of 73 and 21 &mgr;M for N-acetyl-S-trans, trans-farnesyl-L-cysteine and N-acetyl-S-all-trans-geranylgeranyl-L-cysteine, respectively. Furthermore, competition analysis indicates that the same enzyme is responsible for both activities. These results suggest that alpha-carboxyl methylation is a step in the maturation of isoprenylated proteins in plants.
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Affiliation(s)
- DN Crowell
- Department of Biology, Indiana University-Purdue University at Indianapolis, 723 West Michigan Street, Indianapolis, Indiana 46202 (D.N.C., S.K.R.)
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Abstract
Prenylated proteins have been shown to function in important cellular regulatory processes including signal transduction. The enzymes involved in protein prenylation, farnesyl transferase and geranylgeranyl transferase, have been recent targets for development of cancer chemotherapeutics. We have initiated a systematic study of protein prenyl transferases of the malaria parasite, Plasmodium falciparum, to determine whether these enzymes can be developed as targets for antimalarial chemotherapy. We report here the identification of protein farnesyl transferase and protein geranylgeranyl transferase-I in the malaria parasite, P. falciparum. The farnesyl transferase has been partially purified from the cytosolic fraction through ammonium sulfate precipitation and Mono-Q chromatography. Farnesyl and geranylgeranyl transferase-I activities are present at all stages of P. falciparum intraerythrocytic development with maximum specific activity in the ring stage. Geranylgeranyl transferase-I specific activity is two times that of farnesyl transferase in the ring stage. Peptidomimetics and prenyl analogues of protein farnesyl transferase substrates were tested as in vitro inhibitors of partially purified P. falciparum prenyl transferase and of malaria parasite growth. The peptidomimetics were significantly more potent inhibitors than lipid substrate analogues of both the activity of Mono-Q purified enzyme and parasite growth in intraerythrocytic cultures. Exposure of the parasite to the peptidomimetic L-745,631 also showed significant inhibition of morphological development beyond the trophozoite stage. These studies suggest the potential of designing or identifying differential inhibitors of P. falciparum and mammalian prenyl transferases as an approach to novel malaria therapy.
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Affiliation(s)
- D Chakrabarti
- Department of Molecular Biology, Microbiology and Center for Diagnostics and Drug Development, University of Central Florida, Orlando 322816-2360, USA.
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Yokoyama K, Trobridge P, Buckner FS, Scholten J, Stuart KD, Van Voorhis WC, Gelb MH. The effects of protein farnesyltransferase inhibitors on trypanosomatids: inhibition of protein farnesylation and cell growth. Mol Biochem Parasitol 1998; 94:87-97. [PMID: 9719512 DOI: 10.1016/s0166-6851(98)00053-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Attachment of the prenyl groups farnesyl and geranylgeranyl to specific eukaryotic cell proteins by protein prenyltransferases is required for the functioning of a number of cellular processes including signal transduction. In this study it was found that previously reported inhibitors of mammalian protein farnesyltransferase (PFT) [those that mimic the substrate farnesyl pyrophosphate and those that mimic the protein acceptor of the farnesyl group (CaaX mimetic)] inhibit in vitro farnesylation catalyzed by partially purified Trypanosoma brucei (T. brucei) PFT. The most potent PFT inhibitors at concentrations of 3-10 microM inhibit the growth of insect (procyclic) and bloodstream forms of T. brucei. One of the PFT inhibitors was found to block the incorporation of radiolabeled mevalonic acid (the precursor of prenyl groups) into specific T. brucei proteins. This study also shows that protein prenylation occurs in the protozoan parasites Trypanosoma cruzi (T. cruzi) and Leishmania mexicana (L. mexicana). The growth of T. cruzi intracellular form (amastigote) is also sensitive to PFT inhibitors, whereas the insect form (epimastigote) is considerably more resistant to inhibition of protein farnesylation. On the other hand, growth of 3T3 fibroblast cells (host cells for amastigote growth) was not affected by up to 100 microM PFT inhibitors. The growth of L. mexicana insect form (promastigote) is modestly inhibited by protein farnesyltransferase inhibitors. These results suggest the potential for the development of PFT inhibitors for treating trypanosomiasis and leishmaniasis.
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Affiliation(s)
- K Yokoyama
- Department of Chemistry, University of Washington, Seattle 98195-1700, USA
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Abstract
The vast majority of signalling pathways in mammalian cells are mediated by heterotrimeric (alpha betagamma) G proteins. Reviewed here is regulation of signal transduction by the betagamma complex at different protein interfaces: subunit-subunit, receptor-G protein and G protein-effector. The role of diverse beta and gamma subunit types in achieving specificity in signalling and potentially unidentified functions for these subunits also are discussed.
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Affiliation(s)
- N Gautam
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Morishita R, Ueda H, Kato K, Asano T. Identification of two forms of the gamma subunit of G protein, gamma10 and gamma11, in bovine lung and their tissue distribution in the rat. FEBS Lett 1998; 428:85-8. [PMID: 9645481 DOI: 10.1016/s0014-5793(98)00498-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Two forms of the gamma subunit of G protein were purified from bovine lung, and were identified as gamma10 and gamma11 by analyses of partial amino acid sequences and reactivity with specific antibodies. The N-terminal amino acid residue of gamma11 was an unmodified Pro2, and the purified gamma11 was freed from beta even under non-denaturing conditions. Western blots with specific antibodies against gamma10 and gamma11 showed that both gamma subunits are present in a variety of tissues in the rat, with a particular abundance of gamma11 in the platelets.
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Affiliation(s)
- R Morishita
- Department of Biochemistry, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Japan
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Abstract
A specific set of proteins in eukaryotic cells contain covalently attached carboxy-terminal prenyl groups (15-carbon farnesyl and 20-carbon geranylgeranyl). Many of them are signaling proteins including Ras, heterotrimeric G proteins and Rab proteins. The protein prenyltransferases which attach prenyl groups to proteins have been well characterized, and an X-ray structure is available for protein farnesyltransferase. Inhibitors of protein farnesyltransferase are showing sufficient promise in preclinical trials as anti-cancer drugs to warrant widespread interest in the pharmaceutical industry.
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Affiliation(s)
- M H Gelb
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195, USA.
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Abstract
alpha and betagamma subunits of G proteins are thought to transduce signals from cell surface receptors to intracellular effector molecules. Galpha and Gbetagamma have also been implicated in cell growth and differentiation, perhaps due to their association with cytoskeletal components. In this report Gbetagamma is shown to modulate the cytoskeleton by regulation of microtubule assembly. Specificity among betagamma species exists, as beta1gamma2 stimulates microtubule assembly, and beta1gamma1 is without any effect. Furthermore, a mutant beta1gamma2, beta1gamma2(C68S), which does not undergo prenylation and subsequent carboxyl-terminal processing on the gamma subunit, does not stimulate the formation of microtubules. beta immunoreactivity was detected exclusively in the microtubule fraction after assembly in the presence of beta1gamma2, suggesting a preferential association with microtubules rather than soluble tubulin. Crude microtubule fractions from ovine brain contain Gbetagamma, and electron microscopy reveals a specific association with microtubules. The decoration of microtubules by Gbetagamma appears to be strikingly similar to the periodic pattern observed for microtubule-associated proteins, suggesting a similar site of activation of microtubule assembly by both agents. It is suggested that reformation of the cytoskeleton represents an additional cellular process mediated by Gbetagamma.
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Affiliation(s)
- S Roychowdhury
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
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Affiliation(s)
- M L Foegh
- Department of Surgery, Georgetown University Medical Center, Washington, DC, USA.
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