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Saini LK, Bheri M, Pandey GK. Protein phosphatases and their targets: Comprehending the interactions in plant signaling pathways. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 134:307-370. [PMID: 36858740 DOI: 10.1016/bs.apcsb.2022.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Protein phosphorylation is a vital reversible post-translational modification. This process is established by two classes of enzymes: protein kinases and protein phosphatases. Protein kinases phosphorylate proteins while protein phosphatases dephosphorylate phosphorylated proteins, thus, functioning as 'critical regulators' in signaling pathways. The eukaryotic protein phosphatases are classified as phosphoprotein phosphatases (PPP), metallo-dependent protein phosphatases (PPM), protein tyrosine (Tyr) phosphatases (PTP), and aspartate (Asp)-dependent phosphatases. The PPP and PPM families are serine (Ser)/threonine (Thr) specific phosphatases (STPs) that dephosphorylate Ser and Thr residues. The PTP family dephosphorylates Tyr residues while dual-specificity phosphatases (DsPTPs/DSPs) dephosphorylate Ser, Thr, and Tyr residues. The composition of these enzymes as well as their substrate specificity are important determinants of their functional significance in a number of cellular processes and stress responses. Their role in animal systems is well-understood and characterized. The functional characterization of protein phosphatases has been extensively covered in plants, although the comprehension of their mechanistic basis is an ongoing pursuit. The nature of their interactions with other key players in the signaling process is vital to our understanding. The substrates or targets determine their potential as well as magnitude of the impact they have on signaling pathways. In this article, we exclusively overview the various substrates of protein phosphatases in plant signaling pathways, which are a critical determinant of the outcome of various developmental and stress stimuli.
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Affiliation(s)
- Lokesh K Saini
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India.
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2
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Zhang S, Xia Y. Identification of genes preferentially expressed during microcycle conidiation of Metarhizium anisopliae using suppression subtractive hybridization. FEMS Microbiol Lett 2008; 286:71-7. [PMID: 18625022 DOI: 10.1111/j.1574-6968.2008.01257.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Microcycle conidiation has been defined as the production of conidia directly by a spore without the intervention of hyphal growth. The molecular mechanisms underlying this process are still poorly understood. Suppression subtractive hybridization was used here to isolate the genes preferentially expressed during microcycle conidiation vs. in normal conidiation hypha of Metarhizium anisopliae CQMa102, a common fungal pathogen of locusts. A total of 1600 clones from the subtracted cDNA library were screened by cDNA array dot blotting and 221 unique expressed sequence tags were identified as being differentially expressed. These genes were found to be homologous genes involved in various cellular processes, including general metabolism, protein synthesis, energy, cell-cycle and DNA processing, cellular transport, transcription, signal transduction and stress response. Real-time reverse transcriptase PCR assay of six randomly selected genes revealed that they are all highly expressed during microcycle conidiation.
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Affiliation(s)
- Shizhu Zhang
- Genetic Engineering Research Center, College of Bioengineering, Chongqing University and Chongqing Engineering Research Center for Fungal Insecticides, Chongqing, China
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Feng B, Zhao CH, Tanaka S, Imanaka H, Imamura K, Nakanishi K. TPR domain of Ser/Thr phosphatase of Aspergillus oryzae shows no auto-inhibitory effect on the dephosphorylation activity. Int J Biol Macromol 2007; 41:281-5. [PMID: 17475320 DOI: 10.1016/j.ijbiomac.2007.03.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 03/01/2007] [Accepted: 03/15/2007] [Indexed: 11/21/2022]
Abstract
A Ser/Thr phosphatase gene cloned from Aspergillus oryzae, aoppt, revealed that the tetratricopeptide repeat (TPR) and catalytic domains of the full-length AoPPT are located at the N- and C-terminal regions, respectively, similar to those of human Ser/Thr phosphatase 5 (PP5) and yeast Ppt1. Four different regions of AoPPT, namely, a full-length polypeptide, the catalytic domain, the catalytic domain plus C-terminal 15 amino-acid residues and the TPR domain were expressed in Escherichia coli and their roles in dephosphorylation activity were examined, using p-nitrophenyl phosphate as the substrate. The full-length AoPPT showed the highest dephosphorylation activity while the catalytic domain had the lowest activity. The activity of the catalytic domain was not inhibited by the presence of the TPR domain and arachidonic acid did not increase the activity of the full-length enzyme. These findings suggest that the integrity of the entire enzyme would be necessary for its full activity to be expressed.
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Affiliation(s)
- Bin Feng
- Department of Bioscience and Biotechnology, Faculty of Engineering, Okayama University, 3-1-1, Tsushima-Naka, Okayama 700-8530, Japan
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Mills E, Price HP, Johner A, Emerson JE, Smith DF. Kinetoplastid PPEF phosphatases: dual acylated proteins expressed in the endomembrane system of Leishmania. Mol Biochem Parasitol 2006; 152:22-34. [PMID: 17169445 PMCID: PMC1885993 DOI: 10.1016/j.molbiopara.2006.11.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 11/02/2006] [Accepted: 11/14/2006] [Indexed: 12/02/2022]
Abstract
Bioinformatic analyses have been used to identify potential downstream targets of the essential enzyme N-myristoyl transferase in the TriTryp species, Leishmania major, Trypanosoma brucei and Trypanosoma cruzi. These database searches predict ∼60 putative N-myristoylated proteins with high confidence, including both previously characterised and novel molecules. One of the latter is an N-myristoylated protein phosphatase which has high sequence similarity to the Protein Phosphatase with EF-Hand (PPEF) proteins identified in sensory cells of higher eukaryotes. In L. major and T. brucei, the PPEF-like phosphatases are encoded by single-copy genes and are constitutively expressed in all parasite life cycle stages. The N-terminus of LmPPEF is a substrate for N-myristoyl transferase and is also palmitoylated in vivo. The wild type protein has been localised to the endocytic system by immunofluorescence. The catalytic and fused C-terminal domains of the kinetoplastid and other eukaryotic PPEFs share high sequence similarity, but unlike their higher eukaryotic relatives, the C-terminal parasite EF-hand domains are degenerate and do not bind calcium.
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Affiliation(s)
- Elena Mills
- Wellcome Trust Laboratories for Molecular Parasitology, Centre for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Helen P. Price
- Wellcome Trust Laboratories for Molecular Parasitology, Centre for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, UK
- Immunology and Infection Unit, Department of Biology, University of York, Heslington, York YO10 5YW, UK
| | - Andrea Johner
- Immunology and Infection Unit, Department of Biology, University of York, Heslington, York YO10 5YW, UK
| | - Jenny E. Emerson
- Wellcome Trust Laboratories for Molecular Parasitology, Centre for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Deborah F. Smith
- Wellcome Trust Laboratories for Molecular Parasitology, Centre for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, UK
- Immunology and Infection Unit, Department of Biology, University of York, Heslington, York YO10 5YW, UK
- Corresponding author at: Immunology and Infection Unit, Department of Biology, University of York, Heslington, York YO10 5YW, UK. Tel.: +44 1904 328843; fax: +44 1904 328844.
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Feng B, Morita M, Imanaka H, Imamura K, Nakanishi K. Identification of genes from Aspergillus oryzae that are preferentially expressed in membrane-surface liquid culture. J Biosci Bioeng 2006; 102:470-3. [PMID: 17189178 DOI: 10.1263/jbb.102.470] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 08/09/2006] [Indexed: 11/17/2022]
Abstract
We identified 22 genes from Aspergillus oryzae that are preferentially expressed in membrane-surface liquid culture (MSLC), among which Ser/Thr protein kinase (aopk1) and phosphatase (aoppt) genes were cloned. We also revealed that aopk1 encodes a protein with an N-terminal sequence 150 amino acid residues longer than that predicted from the registered sequence in GenBank.
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Affiliation(s)
- Bin Feng
- Department of Bioscience and Biotechnology, Faculty of Engineering, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan
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Zeke T, Morrice N, Vázquez-Martin C, Cohen P. Human protein phosphatase 5 dissociates from heat-shock proteins and is proteolytically activated in response to arachidonic acid and the microtubule-depolymerizing drug nocodazole. Biochem J 2005; 385:45-56. [PMID: 15383005 PMCID: PMC1134672 DOI: 10.1042/bj20040690] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ppp5 (protein phosphatase 5) is a serine/threonine protein phosphatase that has been conserved throughout eukaryotic evolution. In mammalian cells, FLAG-tagged Ppp5 and endogenous Ppp5 are found to interact with endogenous Hsp (heat-shock protein) 70, as well as Hsp90. Incubation of cells with arachidonic acid or the microtubule-depolymerizing agent, nocodazole, causes loss of interaction of Hsp70 and Hsp90 with FLAG-tagged Ppp5 and increase of Ppp5 activity. In response to the same treatments, endogenous Ppp5 undergoes proteolytic cleavage of the N- and C-termini, with the subsequent appearance of high-molecular-mass species. The results indicate that Ppp5 is activated by proteolysis on dissociation from Hsps, and is destroyed via the proteasome after ubiquitination. Cleavage at the C-terminus removes a nuclear localization sequence, allowing these active cleaved forms of Ppp5 to translocate to the cytoplasm. The response of Ppp5 to arachidonic acid and nocodazole suggests that Ppp5 may be required for stress-related processes that can sometimes cause cell-cycle arrest, and leads to the first description for in vivo regulation of Ppp5 activity.
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Affiliation(s)
- Tamás Zeke
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Nick Morrice
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Cristina Vázquez-Martin
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Patricia T. W. Cohen
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
- To whom correspondence should be addressed (email )
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Borkovich KA, Alex LA, Yarden O, Freitag M, Turner GE, Read ND, Seiler S, Bell-Pedersen D, Paietta J, Plesofsky N, Plamann M, Goodrich-Tanrikulu M, Schulte U, Mannhaupt G, Nargang FE, Radford A, Selitrennikoff C, Galagan JE, Dunlap JC, Loros JJ, Catcheside D, Inoue H, Aramayo R, Polymenis M, Selker EU, Sachs MS, Marzluf GA, Paulsen I, Davis R, Ebbole DJ, Zelter A, Kalkman ER, O'Rourke R, Bowring F, Yeadon J, Ishii C, Suzuki K, Sakai W, Pratt R. Lessons from the genome sequence of Neurospora crassa: tracing the path from genomic blueprint to multicellular organism. Microbiol Mol Biol Rev 2004; 68:1-108. [PMID: 15007097 PMCID: PMC362109 DOI: 10.1128/mmbr.68.1.1-108.2004] [Citation(s) in RCA: 434] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We present an analysis of over 1,100 of the approximately 10,000 predicted proteins encoded by the genome sequence of the filamentous fungus Neurospora crassa. Seven major areas of Neurospora genomics and biology are covered. First, the basic features of the genome, including the automated assembly, gene calls, and global gene analyses are summarized. The second section covers components of the centromere and kinetochore complexes, chromatin assembly and modification, and transcription and translation initiation factors. The third area discusses genome defense mechanisms, including repeat induced point mutation, quelling and meiotic silencing, and DNA repair and recombination. In the fourth section, topics relevant to metabolism and transport include extracellular digestion; membrane transporters; aspects of carbon, sulfur, nitrogen, and lipid metabolism; the mitochondrion and energy metabolism; the proteasome; and protein glycosylation, secretion, and endocytosis. Environmental sensing is the focus of the fifth section with a treatment of two-component systems; GTP-binding proteins; mitogen-activated protein, p21-activated, and germinal center kinases; calcium signaling; protein phosphatases; photobiology; circadian rhythms; and heat shock and stress responses. The sixth area of analysis is growth and development; it encompasses cell wall synthesis, proteins important for hyphal polarity, cytoskeletal components, the cyclin/cyclin-dependent kinase machinery, macroconidiation, meiosis, and the sexual cycle. The seventh section covers topics relevant to animal and plant pathogenesis and human disease. The results demonstrate that a large proportion of Neurospora genes do not have homologues in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. The group of unshared genes includes potential new targets for antifungals as well as loci implicated in human and plant physiology and disease.
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Affiliation(s)
- Katherine A Borkovich
- Department of Plant Pathology, University of California, Riverside, California 92521, USA. Katherine/
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Jeong JY, Johns J, Sinclair C, Park JM, Rossie S. Characterization of Saccharomyces cerevisiae protein Ser/Thr phosphatase T1 and comparison to its mammalian homolog PP5. BMC Cell Biol 2003; 4:3. [PMID: 12694636 PMCID: PMC153538 DOI: 10.1186/1471-2121-4-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2002] [Accepted: 03/28/2003] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Protein Ser/Thr phosphatase 5 (PP5) and its Saccharomyces cerevisiae homolog protein phosphatase T1 (Ppt1p) each contain an N-terminal domain consisting of several tetratricopeptide repeats (TPRs) and a C-terminal catalytic domain that is related to the catalytic subunits of protein phosphatases 1 and 2A, and calcineurin. Analysis of yeast Ppt1p could provide important clues to the function of PP5 and its homologs, however it has not yet been characterized at the biochemical or cellular level. RESULTS The specific activity of recombinant Ppt1p toward the artificial substrates 32P-myelin basic protein (MBP) and 32P-casein was similar to that of PP5. Dephosphorylation of 32P-MBP, but not 32P-casein, was stimulated by unsaturated fatty acids and by arachidoyl coenzyme A. Limited proteolysis of Ppt1p removed the TPR domain and abrogated lipid stimulation. The remaining catalytic fragment exhibited a two-fold increase in activity toward 32P-MBP, but not 32P-casein. Removal of the C terminus increased Ppt1p activity toward both substrates two fold, but did not prevent further stimulation of activity toward 32P-MBP by lipid treatment. Ppt1p was localized throughout the cell including the nucleus. Levels of PPT1 mRNA and protein peaked in early log phase growth. CONCLUSIONS Many characteristics of Ppt1p are similar to those of PP5, including stimulation of phosphatase activity with some substrates by lipids, and peak expression during periods of rapid cell growth. Unlike PP5, however, proteolytic removal of the TPR domain or C-terminal truncation only modestly increased its activity. In addition, C-terminal truncation did not prevent further activation by lipid. This suggests that these regions play only a minor role in controlling its activity compared to PP5. Ppt1p is present in both the nucleus and cytoplasm, indicating that it may function in multiple compartments. The observation that Ppt1p is most highly expressed during early log phase growth suggests that this enzyme is involved in cell growth or its expression is controlled by metabolic or nutritional signals.
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Affiliation(s)
- Jee-Yeong Jeong
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Jeremiah Johns
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | | | - Jung-Min Park
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Sandra Rossie
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
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Zeke T, Kókai E, Szöor B, Yatzkan E, Yarden O, Szirák K, Fehér Z, Bagossi P, Gergely P, Dombrádi V. Expression of protein phosphatase 1 during the asexual development of Neurospora crassa. Comp Biochem Physiol B Biochem Mol Biol 2003; 134:161-70. [PMID: 12524044 DOI: 10.1016/s1096-4959(02)00188-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We cloned and sequenced the cDNA and the gene encoding the catalytic subunit of protein phosphatase 1 from the filamentous fungus Neurospora crassa. The gene, designated ppp-1 (phosphoprotein phosphatase 1), was mapped by restriction fragment length polymorphism to linkage group III, in the vicinity of con-7 and trp-1. The expression of the gene was monitored by reverse transcriptase and polymerase chain reactions, by Western blotting, and by protein phosphatase activity assays in synchronized cultures. Transcripts of ppp-1 were detected in the dormant conidia. The abundance of ppp-1 mRNA, Ppp-1 protein, and the activity of protein phosphatase 1 increased during germination and subsequent hyphal elongation as well as during the early stages of aerial mycelium formation.
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Affiliation(s)
- Tamás Zeke
- Department of Medical Chemistry, Medical and Health Sciences Center, University of Debrecen, H-4026 Debrecen, Hungary
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Abstract
During the last decade several novel yeast genes encoding proteins related to the PPP family of Ser/Thr protein phosphatases have been discovered and their functional characterization initiated. Most of these novel phosphatases display intriguing structural features and/or are involved in a number of important functions, such as cell cycle regulation, protein synthesis and maintenance of cellular integrity. While in some cases these genes appear to be restricted to fungi, in others similar proteins can be found in higher eukaryotes. This review will summarize the latest advances in our understanding about how these phosphatases are regulated and fulfil their functions in the yeast cell.
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Affiliation(s)
- Joaquín Ariño
- Department de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra Spain.
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Andreeva AV, Kutuzov MA. Nuclear localization of the plant protein Ser/Thr phosphatase PP7. MOLECULAR CELL BIOLOGY RESEARCH COMMUNICATIONS : MCBRC 2001; 4:345-52. [PMID: 11703093 DOI: 10.1006/mcbr.2001.0302] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recently we identified novel plant Ser/Thr phosphatases, termed PP7, which belong to the PPP family and have no known close homologs in other kingdoms. We now addressed the intracellular location of Arabidopsis thaliana PP7 using GFP fusions and confocal laser scanning microscopy. PP7. GFP fusion was expressed transiently or stably in Nicotiana benthamiana. PP7. GFP was found to be a predominantly nuclear protein. Effects of cytoskeleton-disrupting drugs indicate that cytoskeleton may be required for efficient PP7. GFP delivery to the nucleus. Deletion of a potential nuclear localization signal in the first insert in the catalytic domain, as well as exposure to the dark, cold, high salinity and abscisic acid failed to prevent nuclear localization of PP7. GFP. Deletion of the 44 C-terminal amino acids resulted in a fusion protein located exclusively in the cytoplasm. The results suggest a possible similarity of the nuclear targeting signals in PP7 and the PP5/PPT subfamily.
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Affiliation(s)
- A V Andreeva
- Research School of Biological and Molecular Sciences, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford, OX3 0BP, United Kingdom.
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Borthwick EB, Zeke T, Prescott AR, Cohen PT. Nuclear localization of protein phosphatase 5 is dependent on the carboxy-terminal region. FEBS Lett 2001; 491:279-84. [PMID: 11240142 DOI: 10.1016/s0014-5793(01)02177-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Endogenous and overexpressed protein phosphatase 5 (PP5) localizes to the nucleus and cytoplasm of HeLa cells, while the overexpressed TPR domain of PP5 is restricted to the cytoplasm. Deletion and mutational analysis of human PP5 demonstrates that the C-terminal amino acids 420-499 are essential for nuclear localization and PP5 activity is not required. Since the phosphatase domain terminates at 473, these studies suggest that the highly conserved section (476-491) with the eukaryotic consensus FXAVPHPXPhiXPMAYAN is required for nuclear localization of PP5. Bacterially expressed PP5 is inhibited by several tumor promoters but not by the anticancer drug fostriecin.
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Affiliation(s)
- E B Borthwick
- Medical Research Council Protein Phosphorylation Unit, Department of Biochemistry, MSI/WTB Complex, University of Dundee, Dow Street, DD1 5EH, Scotland, Dundee, UK
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14
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Brown L, Borthwick EB, Cohen PT. Drosophila protein phosphatase 5 is encoded by a single gene that is most highly expressed during embryonic development. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1492:470-6. [PMID: 10899584 DOI: 10.1016/s0167-4781(00)00105-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A putative Drosophila melanogaster homologue of mammalian PP5, termed Dm PP5, was identified from cDNA. Dm PP5 comprises a phosphatase catalytic domain preceded by an amino terminal domain containing three tetratricopeptide repeat motifs and shares 60% overall amino acid identity with human PP5. Genomic restriction analysis identified a single Dm PP5 gene that was mapped to the third chromosome at locus 85E10-12 and a strain carrying a deletion that encompasses this gene was identified. Dm PP5 mRNA and protein are more highly expressed in the embryo than at later developmental stages, but their expression levels do not always change synchronously. Dm PP5 protein localises to both the nucleus and the cytoplasm of cells at the periphery of newly cellularized embryos.
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Affiliation(s)
- L Brown
- Medical Research Council Protein Phosphorylation Unit, Department of Biochemistry, MSI/WTB Complex, University of Dundee, Dow Street, DD1 5EH, Dundee, UK
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Abstract
The tetratricopeptide repeat (TPR) motif is a protein-protein interaction module found in multiple copies in a number of functionally different proteins that facilitates specific interactions with a partner protein(s). Three-dimensional structural data have shown that a TPR motif contains two antiparallel alpha-helices such that tandem arrays of TPR motifs generate a right-handed helical structure with an amphipathic channel that might accommodate the complementary region of a target protein. Most TPR-containing proteins are associated with multiprotein complexes, and there is extensive evidence indicating that TPR motifs are important to the functioning of chaperone, cell-cycle, transcription, and protein transport complexes. The TPR motif may represent an ancient protein-protein interaction module that has been recruited by different proteins and adapted for specific functions. BioEssays 1999;21:932-939.
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Affiliation(s)
- G L Blatch
- Protein-Structure-Function Research Programme, Department of Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
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16
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Abstract
The tetratricopeptide repeat (TPR) motif is a protein-protein interaction module found in multiple copies in a number of functionally different proteins that facilitates specific interactions with a partner protein(s). Three-dimensional structural data have shown that a TPR motif contains two antiparallel alpha-helices such that tandem arrays of TPR motifs generate a right-handed helical structure with an amphipathic channel that might accommodate the complementary region of a target protein. Most TPR-containing proteins are associated with multiprotein complexes, and there is extensive evidence indicating that TPR motifs are important to the functioning of chaperone, cell-cycle, transcription, and protein transport complexes. The TPR motif may represent an ancient protein-protein interaction module that has been recruited by different proteins and adapted for specific functions. BioEssays 1999;21:932-939.
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Affiliation(s)
- G L Blatch
- Protein-Structure-Function Research Programme, Department of Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
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17
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Abstract
A great variety of cellular functions are regulated by protein serine/threonine phosphatases (PP). This review summarises the current knowledge of the structural features, patterns of expression and involvement in signal transduction pathways of protein serine/threonine phosphatases related to PP5 and RdgC. Designated now as PP5/RdgC subfamily by P. T. W. Cohen in her 1997 study published in Trends in Biochemical Sciences, (Vol. 22, pp. 245-251), this heterogeneous group comprises phosphatases PP5/PPT, containing regulatory domains with tetratricopeptide repeats, RdgC/PPEF, which possess Ca2+-binding EF hand-type sites, and, recently discovered in plants, PP7. PP5 is ubiquitously expressed and appears to be a multifunctional phosphatase involved in a number of different signalling pathways. In contrast, expression of RdgC/PPEF phosphatases and PP7 is confined primarily to specialised sensory cells in animals and plants, respectively, which may be indicative of their more specialised roles in sensory signal transduction.
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Affiliation(s)
- A V Andreeva
- Research School of Biological and Molecular Sciences, Oxford Brookes University, Headington, UK.
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Szöor B, Fehér Z, Zeke T, Gergely P, Yatzkan E, Yarden O, Dombrádi V. pzl-1 encodes a novel protein phosphatase-Z-like Ser/Thr protein phosphatase in Neurospora crassa. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1388:260-6. [PMID: 9774742 DOI: 10.1016/s0167-4838(98)00201-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The gene and cDNA of a novel protein phosphatase were cloned from Neurospora crassa. The pzl-1 gene encompasses three introns and is localized to the left arm of chromosome I between cyt-21 and Fsr-12. It encodes a protein of 58.3 kDa containing a Ser/Pro rich N-terminal segment, and a C-terminal domain that is similar to the catalytic subunit of type 1 protein phosphatases. The first 51 amino acid residues, including a potential N-myristoylation site, as well as the C-terminal domain (about 300 residues) have a high level of sequence identity with yeast PPZ phosphatases. However, residues 52-208 do not share high similarity with other proteins. The mRNA of pzl-1 was detected in all phases of asexual development of the filamentous fungus.
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Affiliation(s)
- B Szöor
- Department of Medical Chemistry, University Medical School of Debrecen, H-4012 Debrecen, Hungary
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