151
|
Hao L, Wang H, Sunter G, Bisaro DM. Geminivirus AL2 and L2 proteins interact with and inactivate SNF1 kinase. THE PLANT CELL 2003; 15:1034-48. [PMID: 12671096 PMCID: PMC152347 DOI: 10.1105/tpc.009530] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2002] [Accepted: 01/24/2003] [Indexed: 05/18/2023]
Abstract
Geminivirus AL2 and L2 proteins cause enhanced susceptibility, characterized primarily by an increase in viral infectivity, when expressed in transgenic plants. Here, we present genetic and biochemical evidence that enhanced susceptibility is attributable to the interaction of AL2 and L2 with SNF1 kinase, a global regulator of metabolism. Specifically, we show that AL2 and L2 inactivate SNF1 in vitro and in vivo. We further demonstrate that expression of an antisense SNF1 transgene in Nicotiana benthamiana plants causes enhanced susceptibility similar to that conditioned by the AL2 and L2 transgenes, whereas SNF1 overexpression leads to enhanced resistance. Transgenic plants expressing an AL2 protein that lacks a significant portion of the SNF1 interaction domain do not display enhanced susceptibility. Together, these observations suggest that the metabolic alterations mediated by SNF1 are a component of innate antiviral defenses and that SNF1 inactivation by AL2 and L2 is a counterdefensive measure. They also indicate that geminiviruses are able to modify host metabolism to their own advantage, and they provide a molecular link between metabolic status and inherent susceptibility to viral pathogens.
Collapse
Affiliation(s)
- Linhui Hao
- Department of Molecular Genetics, Plant Biotechnology Center, The Ohio State University, Columbus, Ohio 43210, USA
| | | | | | | |
Collapse
|
152
|
Dinant S, Clark AM, Zhu Y, Vilaine F, Palauqui JC, Kusiak C, Thompson GA. Diversity of the superfamily of phloem lectins (phloem protein 2) in angiosperms. PLANT PHYSIOLOGY 2003; 131:114-28. [PMID: 12529520 PMCID: PMC166792 DOI: 10.1104/pp.013086] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Phloem protein 2 (PP2) is one of the most abundant and enigmatic proteins in the phloem sap. Although thought to be associated with structural P-protein, PP2 is translocated in the assimilate stream where its lectin activity or RNA-binding properties can exert effects over long distances. Analyzing the diversity of these proteins in vascular plants led to the identification of PP2-like genes in species from 17 angiosperm and gymnosperm genera. This wide distribution of PP2 genes in the plant kingdom indicates that they are ancient and common in vascular plants. Their presence in cereals and gymnosperms, both of which lack structural P-protein, also supports a wider role for these proteins. Within this superfamily, PP2 proteins have considerable size polymorphism. This is attributable to variability in the length of the amino terminus that extends from a highly conserved domain. The conserved PP2 domain was identified in the proteins encoded by six genes from several cucurbits, celery (Apium graveolens), and Arabidopsis that are specifically expressed in the sieve element-companion cell complex. The acquisition of additional modular domains in the amino-terminal extensions of other PP2-like proteins could reflect divergence from its phloem function.
Collapse
Affiliation(s)
- Sylvie Dinant
- Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, Versailles 78026, France
| | | | | | | | | | | | | |
Collapse
|
153
|
Lovas A, Bimbó A, Szabó L, Bánfalvi Z. Antisense repression of StubGAL83 affects root and tuber development in potato. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 33:139-147. [PMID: 12943548 DOI: 10.1046/j.1365-313x.2003.016015.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
StubGAL83 is a potato gene that encodes the beta-subunit of a protein kinase complex similar to the yeast SNF1, and the mammalian AMPK complexes that are modulated by changes in the cellular AMP/ATP ratio and are important regulators of metabolic and stress responses. Here we show that the expression of StubGAL83 in potato foliage is much higher in the dark than in the light and can be repressed by metabolisable sugars in the dark. The amounts of StubGAL83 mRNA are higher in sink than in source leaves. To unravel the role of StubGAL83, transgenic potato plants expressing a part of the StubGAL83 cDNA in antisense orientation under the control of the constitutive CaMV35S promoter were generated. Northern analysis revealed a reduction up to 90-95% in StubGAL83 mRNA accumulation in leaves of seven lines. Five out of these seven lines exhibited a reduction of StubGAL83 mRNA levels also in root and tuber tissues. Independent on the type of repression, the transgenic lines showed a delay in rooting and an increased sensitivity to salt stress. The roots were stunted and possessed less pronounced tap roots than the controls albeit with different severity in the different transgenic lines. The root cells were smaller and some of them had irregular shape. Tuberisation of the antisense-StubGAL83 lines was delayed, the size of the tubers was reduced while the number of tubers per plant was increased. These results together suggest that StubGAL83 affects root and tuber development probably by altering the metabolic status of the leaves.
Collapse
Affiliation(s)
- Agnes Lovas
- Agricultural Biotechnology Center, H-2101 Gödöllõ, PO Box 411, Hungary
| | | | | | | |
Collapse
|
154
|
Vitale A. Physical methods. PLANT MOLECULAR BIOLOGY 2002; 50:825-836. [PMID: 12516856 DOI: 10.1023/a:1021209702115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Despite the advent of high-output, recombinant DNA-based screening strategies, many important protein-protein interactions in the plant cell have been and still are revealed using co-sedimentation, affinity chromatography and other affinity techniques, co-immunoprecipitation and cross-linking. The advantages of these techniques, the care that should be taken interpreting the data obtained and the possible ways to overcome pitfalls are illustrated.
Collapse
Affiliation(s)
- Alessandro Vitale
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, via Bassini 15, 20133 Milano, Italy.
| |
Collapse
|
155
|
Xie Y, Varshavsky A. UFD4 lacking the proteasome-binding region catalyses ubiquitination but is impaired in proteolysis. Nat Cell Biol 2002; 4:1003-7. [PMID: 12447385 DOI: 10.1038/ncb889] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2002] [Revised: 10/05/2002] [Accepted: 10/22/2002] [Indexed: 11/09/2022]
Abstract
The ubiquitin system recognizes degradation signals of protein substrates through E3-E2 ubiquitin ligases, which produce a substrate-linked multi-ubiquitin chain. Ubiquitinated substrates are degraded by the 26S proteasome, which consists of the 20S protease and two 19S particles. We previously showed that UBR1 and UFD4, two E3 ligases of the yeast Saccharomyces cerevisiae, interact with specific proteasomal subunits. Here we advance this analysis for UFD4 and show that it interacts with RPT4 and RPT6, two subunits of the 19S particle. The 201-residue amino-terminal region of UFD4 is essential for its binding to RPT4 and RPT6. UFD4(DeltaN), which lacks this N-terminal region, adds ubiquitin to test substrates with apparently wild-type activity, but is impaired in conferring short half-lives on these substrates. We propose that interaction of a targeted substrate with the 26S proteasome involves contacts of specific proteasomal subunits with the substrate-bound ubiquitin ligase, with the substrate-linked multi-ubiquitin chain and with the substrate itself. This multiple-site binding may function to slow down dissociation of the substrate from the proteasome and to facilitate the unfolding of substrate through ATP-dependent movements of the chaperone subunits of the 19S particle.
Collapse
Affiliation(s)
- Youming Xie
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
| | | |
Collapse
|
156
|
Ellis C, Turner JG, Devoto A. Protein complexes mediate signalling in plant responses to hormones, light, sucrose and pathogens. PLANT MOLECULAR BIOLOGY 2002; 50:971-980. [PMID: 12516865 DOI: 10.1023/a:1021291522243] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Living organisms use complex pathways of signal perception and transduction to respond to stimuli in their environments. In plants, putative signal transduction components have been identified through mutant screens and comparative analysis of genome sequences of model eukaryotes. Several pieces in a large series of puzzles have now been identified and a current challenge is to determine how these pieces interconnect. Functional analysis of the encoded proteins has necessitated a change from genetic to biochemical approaches. In recent years, the application of techniques such as two-hybrid screening and epitope tagging has facilitated the study of protein-protein interactions and has increased our understanding of cellular signalling mechanisms. One focus of present research is the ubiquitin/proteasome-mediated degradation of proteins. Increasing evidence suggests this is a control common to many plant signalling pathways including development and responsiveness to hormones, light and sucrose. A central challenge in the study of plant disease resistance has been to identify protein complexes that contain host defence proteins and pathogenicity factors. In this review we summarize the latest developments in these areas where the existence of protein complexes has been demonstrated to be of fundamental importance in plant signalling.
Collapse
Affiliation(s)
- Christine Ellis
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | | | | |
Collapse
|
157
|
Criqui MC, Genschik P. Mitosis in plants: how far we have come at the molecular level? CURRENT OPINION IN PLANT BIOLOGY 2002; 5:487-493. [PMID: 12393010 DOI: 10.1016/s1369-5266(02)00297-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The basic mechanism of mitosis is universally conserved in all eucaryotes, but specific solutions to achieve this process have been adapted by different organisms during evolution. Although cytological studies of plant cells have contributed to our understanding of chromatin dynamics during mitosis, many of the molecular mechanisms that control mitosis have been identified in yeast and animal cells. Nevertheless, recent advances have begun to fill the gaps in our understanding of how mitosis is regulated in plants, and raise intriguing questions to be answered in the future.
Collapse
Affiliation(s)
- Marie Claire Criqui
- Institut de Biologie Moléculaire des Plantes du CNRS, 12, rue du Général Zimmer, 67084 Cédex, Strasbourg, France
| | | |
Collapse
|
158
|
Devoto A, Nieto-Rostro M, Xie D, Ellis C, Harmston R, Patrick E, Davis J, Sherratt L, Coleman M, Turner JG. COI1 links jasmonate signalling and fertility to the SCF ubiquitin-ligase complex in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 32:457-66. [PMID: 12445118 DOI: 10.1046/j.1365-313x.2002.01432.x] [Citation(s) in RCA: 276] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Jasmonates (JAs) regulate Arabidopsis thaliana wound and defence responses, pollen development, and stress-related growth inhibition. Significantly, each of these responses requires COI1, an F-box protein. Other F-box proteins interact with SKP1 and cullin proteins to form SCF complexes that selectively recruit regulatory proteins targeted for ubiquitination. To determine whether COI1 also functions in an SCF complex, we have characterized Arabidopsis proteins that bind to COI1. An Arabidopsis cDNA expression library was screened in yeast for clones that produce proteins which can bind to COI1. We recovered two SKP1 homologues and a histone deacetylase. The Arabidopsis F-box protein TIR1 interacted with SKP1 proteins, but not with the histone deacetylase. Mutant COI1 proteins revealed that the F-box is required for interaction with SKP1s, but that sequences in leucine-rich repeat domains are required for interaction with the histone deacetylase. Epitope-tagged COI1 was introduced into Arabidopsis plants and cell cultures. Co-immunoprecipitation experiments confirmed the interaction in planta of COI1 with SKP1-like proteins and histone deacetylase, and also indicated that COI1 interacted with cullin. These results suggest that COI1 forms an SCFCOI1 complex in vivo. COI1 is therefore expected to form a functional E3-type ubiquitin ligase in plants and to regulate expression of jasmonate responsive genes, possibly by targeted ubiquitination of a histone deacetylase.
Collapse
Affiliation(s)
- Alessandra Devoto
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK, and John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
159
|
Van Der Wel H, Morris HR, Panico M, Paxton T, Dell A, Kaplan L, West CM. Molecular Cloning and Expression of a UDP-N-acetylglucosamine (GlcNAc):Hydroxyproline Polypeptide GlcNAc-transferase That Modifies Skp1 in the Cytoplasm ofDictyostelium. J Biol Chem 2002; 277:46328-37. [PMID: 12244115 DOI: 10.1074/jbc.m208024200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Skp1 is a ubiquitous eukaryotic protein found in several cytoplasmic and nuclear protein complexes, including the SCF-type E3 ubiquitin ligase. In Dictyostelium, Skp1 is hydroxylated at proline 143, which is then modified by a pentasaccharide chain. The enzyme activity that attaches the first sugar, GlcNAc, was previously shown to copurify with the GnT51 polypeptide whose gene has now been cloned using a proteomics approach based on a quadrupole/time-of-flight hybrid mass spectrometer. When expressed in Escherichia coli, recombinant GnT51 exhibits UDP-GlcNAc:hydroxyproline Skp1 GlcNAc-transferase activity. Based on amino acid sequence alignments, GnT51 defines a new family of microbial polypeptide glycosyltransferases that appear to be distantly related to the catalytic domain of mucin-type UDP-GalNAc:Ser/Thr polypeptide alpha-GalNAc-transferases expressed in the Golgi compartment of animal cells. This relationship is supported by the effects of site-directed mutagenesis of GnT51 amino acids associated with its predicted DXD-like motif, DAH. In contrast, GnT51 lacks the N-terminal signal anchor sequence present in the Golgi enzymes, consistent with the cytoplasmic localization of the Skp1 acceptor substrate and the biochemical properties of the enzyme. The first glycosylation step of Dictyostelium Skp1 is concluded to be mechanistically similar to that of animal mucin type O-linked glycosylation, except that it occurs in the cytoplasm rather than the Golgi compartment of the cell.
Collapse
Affiliation(s)
- Hanke Van Der Wel
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, Florida 32610-0235, USA
| | | | | | | | | | | | | |
Collapse
|
160
|
Kuroda H, Takahashi N, Shimada H, Seki M, Shinozaki K, Matsui M. Classification and expression analysis of Arabidopsis F-box-containing protein genes. PLANT & CELL PHYSIOLOGY 2002; 43:1073-85. [PMID: 12407186 DOI: 10.1093/pcp/pcf151] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
F-box proteins regulate diverse cellular processes, including cell cycle transition, transcriptional regulation and signal transduction, by playing roles in Skp1p-cullin-F-box protein (SCF) complexes or non-SCF complexes. F-box proteins are encoded by a large gene family. Our database search revealed that at least 568 F-box protein genes are present in the Arabidopsis thaliana (Arabidopsis) genome. Domain search analysis using SMART and Pfam-A databases revealed that 67 of the F-box proteins contained Kelch repeats and 29 contained leucine-rich repeats (LRRs). Interestingly only two F-box proteins contained WD40 repeats that are found in many F-box proteins of other organisms. Kelch repeats, LRRs and WD40 repeats are implicated in protein-protein interactions. This analysis also resulted in the finding of several unique functional domains; however, 448 of the F-box proteins did not contain any known domains. Therefore, these proteins were used to search the Pfam-B database to find novel domains, and three putative ones were found. These domain search analyses led us to classify the Arabidopsis F-box proteins into at least 19 groups based on their domain structures. Macro array analysis showed that several F-box protein genes are expressed in a tissue-specific manner.
Collapse
Affiliation(s)
- Hirofumi Kuroda
- Plant Function Exploration Team, Plant Functional Genomics Research Group, Genomic Sciences Center, RIKEN Yokohama Institute, 1-7-22 Suyehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan
| | | | | | | | | | | |
Collapse
|
161
|
Panicot M, Minguet EG, Ferrando A, Alcázar R, Blázquez MA, Carbonell J, Altabella T, Koncz C, Tiburcio AF. A polyamine metabolon involving aminopropyl transferase complexes in Arabidopsis. THE PLANT CELL 2002; 14:2539-51. [PMID: 12368503 PMCID: PMC151234 DOI: 10.1105/tpc.004077] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The conversion of putrescine to spermidine in the biosynthetic pathway of plant polyamines is catalyzed by two closely related spermidine synthases, SPDS1 and SPDS2, in Arabidopsis. In the yeast two-hybrid system, SPDS2 was found to interact with SPDS1 and a novel protein, SPMS (spermine synthase), which is homologous with SPDS2 and SPDS1. SPMS interacts with both SPDS1 and SPDS2 in yeast and in vitro. Unlike SPDS1 and SPDS2, SPMS failed to suppress the speDelta3 deficiency of spermidine synthase in yeast. However, SPMS was able to complement the speDelta4 spermine deficiency in yeast, indicating that SPMS is a novel spermine synthase. The SPDS and SPMS proteins showed no homodimerization but formed heterodimers in vitro. Pairwise coexpression of hemagglutinin- and c-Myc epitope-labeled proteins in Arabidopsis cells confirmed the existence of coimmunoprecipitating SPDS1-SPDS2 and SDPS2-SPMS heterodimers in vivo. The epitope-labeled SPDS and SPMS proteins copurified with protein complexes ranging in size from 650 to 750 kD. Our data demonstrate the existence of a metabolon involving at least the last two steps of polyamine biosynthesis in Arabidopsis.
Collapse
Affiliation(s)
- Mireia Panicot
- Unitat de Fisiologia Vegetal, Facultat de Farmàcia, Universitat de Barcelona, Diagonal 643, 08028-Barcelona, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
162
|
Ríos G, Lossow A, Hertel B, Breuer F, Schaefer S, Broich M, Kleinow T, Jásik J, Winter J, Ferrando A, Farrás R, Panicot M, Henriques R, Mariaux JB, Oberschall A, Molnár G, Berendzen K, Shukla V, Lafos M, Koncz Z, Rédei GP, Schell J, Koncz C. Rapid identification of Arabidopsis insertion mutants by non-radioactive detection of T-DNA tagged genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 32:243-53. [PMID: 12383089 DOI: 10.1046/j.1365-313x.2002.01416.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
To assist in the analysis of plant gene functions we have generated a new Arabidopsis insertion mutant collection of 90 000 lines that carry the T-DNA of Agrobacterium gene fusion vector pPCV6NFHyg. Segregation analysis indicates that the average frequency of insertion sites is 1.29 per line, predicting about 116 100 independent tagged loci in the collection. The average T-DNA copy number estimated by Southern DNA hybridization is 2.4, as over 50% of the insertion loci contain tandem T-DNA copies. The collection is pooled in two arrays providing 40 PCR templates, each containing DNA from either 4000 or 5000 individual plants. A rapid and sensitive PCR technique using high-quality template DNA accelerates the identification of T-DNA tagged genes without DNA hybridization. The PCR screening is performed by agarose gel electrophoresis followed by isolation and direct sequencing of DNA fragments of amplified T-DNA insert junctions. To estimate the mutation recovery rate, 39 700 lines have been screened for T-DNA tags in 154 genes yielding 87 confirmed mutations in 73 target genes. Screening the whole collection with both T-DNA border primers requires 170 PCR reactions that are expected to detect a mutation in a gene with at least twofold redundancy and an estimated probability of 77%. Using this technique, an M2 family segregating a characterized gene mutation can be identified within 4 weeks.
Collapse
Affiliation(s)
- Gabino Ríos
- Max-Planck Institut für Züchtungsforschung, Carl-von-Linné-Weg 10, D-59829 Köln, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
163
|
Gagne JM, Downes BP, Shiu SH, Durski AM, Vierstra RD. The F-box subunit of the SCF E3 complex is encoded by a diverse superfamily of genes in Arabidopsis. Proc Natl Acad Sci U S A 2002; 99:11519-24. [PMID: 12169662 PMCID: PMC123288 DOI: 10.1073/pnas.162339999] [Citation(s) in RCA: 474] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The covalent attachment of ubiquitin is an important determinant for selective protein degradation by the 26S proteasome in plants and animals. The specificity of ubiquitination is often controlled by ubiquitin-protein ligases (or E3s), which facilitate the transfer of ubiquitin to appropriate targets. One ligase type, the SCF E3s are composed of four proteins, cullin1/Cdc53, Rbx1/Roc1/Hrt1, Skp1, and an F-box protein. The F-box protein, which identifies the targets, binds to the Skp1 component of the complex through a degenerate N-terminal approximately 60-aa motif called the F-box. Using published F-boxes as queries, we have identified 694 potential F-box genes in Arabidopsis, making this gene superfamily one of the largest currently known in plants. Most of the encoded proteins contain interaction domains C-terminal to the F-box that presumably participate in substrate recognition. The F-box proteins can be classified via a phylogenetic approach into five major families, which can be further organized into multiple subfamilies. Sequence diversity within the subfamilies suggests that many F-box proteins have distinct functions and/or substrates. Representatives of all of the major families interact in yeast two-hybrid experiments with members of the Arabidopsis Skp family supporting their classification as F-box proteins. For some, a limited preference for Skps was observed, suggesting that a hierarchical organization of SCF complexes exists defined by distinct Skp/F-box protein pairs. Collectively, the data shows that Arabidopsis has exploited the SCF complex and the ubiquitin/26S proteasome pathway as a major route for cellular regulation and that a diverse array of SCF targets is likely present in plants.
Collapse
Affiliation(s)
- Jennifer M Gagne
- Cellular and Molecular Biology Program and the Department of Horticulture, 1575 Linden Drive, University of Wisconsin, Madison, WI 53706, USA
| | | | | | | | | |
Collapse
|
164
|
Kertesz N, Samson J, Debacker C, Wu H, Labastie MC. Cloning and characterization of human and mouse SNRK sucrose non-fermenting protein (SNF-1)-related kinases. Gene 2002; 294:13-24. [PMID: 12234663 DOI: 10.1016/s0378-1119(02)00829-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We previously isolated, from the earliest population of CD34+ hematopoietic progenitors that form in the aorta of the human embryo, a partial DNA complementary to RNA (cDNA) sequence that was later identified as the human homologue of rat sucrose non-fermenting protein (SNF-1) related kinase (rSNRK), a novel SNF-1-related kinase previously characterized in the rat. In the present study we report the cloning of the complete human SNF-1 related kinase (hSNRK) cDNA and show that the gene spans 39.8 kb at region 3p21 and contains six exons. Recombinant expression of the hSNRK coding sequence in Escherichia coli led to the production of a functional protein kinase of 85 kDa. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of hSNRK expression in fetal CD34+ hematopoietic progenitors revealed its continuous expression throughout human development with higher levels in highly dividing CD34+ CD38+ cells compared to quiescent CD34+ CD38- cells. This observation, together with the expression of hSNRK in numerous human leukemic cell lines, may reflect an implication of hSNRK protein in hematopoietic cell proliferation or differentiation. In the mouse, the SNRK cDNA is 4.6-kb-long and encodes a protein of 748 amino acids with a predicted molecular mass of 81,930 Da. The proteins from human, rat and mouse are strongly conserved and are characterized by the presence of a serine/threonine kinase catalytic domain, a bipartite nuclear targeting signal and an ubiquitin-associated domain. In situ hybridization and RT-PCR analysis of the pattern of mSNRK expression in the mouse reveals that it is temporally and spatially regulated during embryogenesis, and widespread expressed in adult tissues.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- Embryo, Mammalian/enzymology
- Embryo, Mammalian/metabolism
- Exons
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Enzymologic
- Genes/genetics
- HL-60 Cells
- Hematopoietic Stem Cells/enzymology
- Hematopoietic Stem Cells/metabolism
- Humans
- In Situ Hybridization
- Introns
- Jurkat Cells
- K562 Cells
- Male
- Molecular Sequence Data
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Rats
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- Nathalie Kertesz
- Howard Hughes Medical Institute and Department of Molecular and Medical Pharmacology, UCLA School of Medicine, Los Angeles, CA 90095-1735, USA
| | | | | | | | | |
Collapse
|
165
|
Leonchiks A, Stavropoulou V, Sharipo A, Masucci MG. Inhibition of ubiquitin-dependent proteolysis by a synthetic glycine-alanine repeat peptide that mimics an inhibitory viral sequence. FEBS Lett 2002; 522:93-8. [PMID: 12095625 DOI: 10.1016/s0014-5793(02)02897-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The glycine-alanine repeat (GAr) of the Epstein-Barr virus nuclear antigen-1 is a cis-acting transferable element that inhibits ubiquitin/proteasome-dependent proteolysis in vitro and in vivo. We have here examined the effect of a synthetic 20-mer GAr oligopeptide on the degradation of iodinated or biotin labeled lysozyme in a rabbit reticulocyte lysates in vitro assay. Micromolar concentrations of the GA-20 peptide inhibited the hydrolysis of lysozyme without significant effect on ubiquitination. Addition of the peptide did not inhibit the hydrolysis of fluorogenic substrate by purified proteasomes and did not affect the ubiquitination of lysozyme. An excess of the peptide failed to compete for binding of a synthetic tetra-ubiquitin complex to the S5a ubiquitin-binding subunit of the 19S regulator, confirming that the GAr does not block the access of ubiquitinated substrates to the proteasome. Our data suggest that the GAr may act by destabilizing the interaction of ubiquitinated substrates with the proteasome and promote the premature release of the substrate.
Collapse
Affiliation(s)
- Ainars Leonchiks
- Microbiology and Tumor Biology Center, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | | | | | | |
Collapse
|
166
|
Shen WH, Parmentier Y, Hellmann H, Lechner E, Dong A, Masson J, Granier F, Lepiniec L, Estelle M, Genschik P. Null mutation of AtCUL1 causes arrest in early embryogenesis in Arabidopsis. Mol Biol Cell 2002; 13:1916-28. [PMID: 12058059 PMCID: PMC117614 DOI: 10.1091/mbc.e02-02-0077] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The SCF (for SKP1, Cullin/CDC53, F-box protein) ubiquitin ligase targets a number of cell cycle regulators, transcription factors, and other proteins for degradation in yeast and mammalian cells. Recent genetic studies demonstrate that plant F-box proteins are involved in auxin responses, jasmonate signaling, flower morphogenesis, photocontrol of circadian clocks, and leaf senescence, implying a large spectrum of functions for the SCF pathway in plant development. Here, we present a molecular and functional characterization of plant cullins. The Arabidopsis genome contains 11 cullin-related genes. Complementation assays revealed that AtCUL1 but not AtCUL4 can functionally complement the yeast cdc53 mutant. Arabidopsis mutants containing transfer DNA (T-DNA) insertions in the AtCUL1 gene were shown to display an arrest in early embryogenesis. Consistently, both the transcript and the protein of the AtCUL1 gene were found to accumulate in embryos. The AtCUL1 protein localized mainly in the nucleus but also weakly in the cytoplasm during interphase and colocalized with the mitotic spindle in metaphase. Our results demonstrate a critical role for the SCF ubiquitin ligase in Arabidopsis embryogenesis.
Collapse
Affiliation(s)
- Wen-Hui Shen
- Institut de Biologie Moléculaire des Plantes du CNRS, 67084 Strasbourg, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
167
|
Chen Y, Peumans WJ, Hause B, Bras J, Kumar M, Proost P, Barre A, Rougé P, Van Damme EJM. Jasmonic acid methyl ester induces the synthesis of a cytoplasmic/nuclear chito-oligosaccharide binding lectin in tobacco leaves. FASEB J 2002; 16:905-7. [PMID: 12039875 DOI: 10.1096/fj.01-0598fje] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In contrast to animal lectins, no evidence has indicated the occurrence of plant lectins, which recognize and bind "endogenous" receptors and accordingly are involved in recognition mechanisms within the organism itself. Here we show that the plant hormone jasmonic acid methyl ester (JAME) induces in leaves of Nicotiana tabacum (var. Samsun NN) the expression of a lectin that is absent from untreated plants. The lectin specifically binds to oligomers of N-acetylglucosamine and is detected exclusively in the cytoplasm and the nucleus. Both the subcellular location and specificity indicate that the Nicotiana tabacum agglutinin (called Nictaba) may be involved in the regulation of gene expression in stressed plants through specific protein-carbohydrate interactions with regulatory cytoplasmic/nuclear glycoproteins. Searches in the databases revealed that many flowering plants contain sequences encoding putative homologues of the tobacco lectin, which suggest that Nictaba is the prototype of a widespread or possibly ubiquitous family of lectins with a specific endogenous role.
Collapse
Affiliation(s)
- Ying Chen
- Laboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven, 3001 Leuven, Belgium
| | | | | | | | | | | | | | | | | |
Collapse
|
168
|
Unno M, Mizushima T, Morimoto Y, Tomisugi Y, Tanaka K, Yasuoka N, Tsukihara T. The structure of the mammalian 20S proteasome at 2.75 A resolution. Structure 2002; 10:609-18. [PMID: 12015144 DOI: 10.1016/s0969-2126(02)00748-7] [Citation(s) in RCA: 391] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The 20S proteasome is the catalytic portion of the 26S proteasome. Constitutively expressed mammalian 20S proteasomes have three active subunits, beta 1, beta 2, and beta 5, which are replaced in the immunoproteasome by interferon-gamma-inducible subunits beta 1i, beta 2i, and beta 5i, respectively. Here we determined the crystal structure of the bovine 20S proteasome at 2.75 A resolution. The structures of alpha 2, beta 1, beta 5, beta 6, and beta 7 subunits of the bovine enzyme were different from the yeast enzyme but enabled the bovine proteasome to accommodate either the constitutive or the inducible subunits. A novel N-terminal nucleophile hydrolase activity was proposed for the beta 7 subunit. We also determined the site of the nuclear localization signals in the molecule. A model of the immunoproteasome was predicted from this constitutive structure.
Collapse
Affiliation(s)
- Masaki Unno
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | | | | | | | | | | | | |
Collapse
|
169
|
Austin MJ, Muskett P, Kahn K, Feys BJ, Jones JDG, Parker JE. Regulatory role of SGT1 in early R gene-mediated plant defenses. Science 2002; 295:2077-80. [PMID: 11847308 DOI: 10.1126/science.1067747] [Citation(s) in RCA: 288] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Animal SGT1 is a component of Skp1-Cullin-F-box protein (SCF) ubiquitin ligases that target regulatory proteins for degradation. Mutations in one (SGT1b) of two highly homologous Arabidopsis SGT1 genes disable early plant defenses conferred by multiple resistance (R) genes. Loss of SGT1b function in resistance is not compensated for by SGT1a. R genes differ in their requirements for SGT1b and a second resistance signaling gene, RAR1, that was previously implicated as an SGT1 interactor. Moreover, SGT1b and RAR1 contribute additively to RPP5-mediated pathogen recognition. These data imply both operationally distinct and cooperative functions of SGT1 and RAR1 in plant disease resistance.
Collapse
Affiliation(s)
- Mark J Austin
- Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | | | | | | | | | | |
Collapse
|
170
|
Fordham-Skelton AP, Chilley P, Lumbreras V, Reignoux S, Fenton TR, Dahm CC, Pages M, Gatehouse JA. A novel higher plant protein tyrosine phosphatase interacts with SNF1-related protein kinases via a KIS (kinase interaction sequence) domain. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 29:705-715. [PMID: 12148529 DOI: 10.1046/j.1365-313x.2002.01250.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A novel protein phosphatase in Arabidopsis thaliana was identified by database searching. This protein, designated AtPTPKIS1, contains a protein tyrosine phosphatase (PTP) catalytic domain and a kinase interaction sequence (KIS) domain. It is predicted to interact with plant SNF1-related kinases (SnRKs), representing central regulators of metabolic and stress responses. AtPTPKIS1 has close homologues in other plant species, both dicots and monocots, but is not found in other kingdoms. The tomato homologue of AtPTPKIS1 was expressed as a recombinant protein and shown to hydrolyse a generic phosphatase substrate, and phosphotyrosine residues in synthetic peptides. The KIS domain of AtPTPKIS1 was shown to interact with the plant SnRK AKIN11 both in vivo in the yeast two-hybrid system, and in vitro in a GST-fusion 'pull down' assay. The genomes of Arabidopsis and other plants contain further predicted proteins related to AtPTPKIS1, which could also interact with SnRKs and act in novel regulatory and signalling pathways.
Collapse
|
171
|
Yamanaka A, Yada M, Imaki H, Koga M, Ohshima Y, Nakayama KI. Multiple Skp1-related proteins in Caenorhabditis elegans: diverse patterns of interaction with Cullins and F-box proteins. Curr Biol 2002; 12:267-75. [PMID: 11864566 DOI: 10.1016/s0960-9822(02)00657-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND The ubiquitin-proteasome pathway of proteolysis controls the abundance of specific regulatory proteins. The SCF complex is a type of ubiquitin-protein ligase (E3) that contributes to this pathway in many biological systems. In yeast and mammals, the SCF complex consists of common components, including Skp1, Cdc53/Cul1, and Rbx1, as well as variable components known as F-box proteins. Whereas only one functional Skp1 gene is present in the human genome, the genome of Caenorhabditis elegans has now been shown to contain at least 21 Skp1-related (skr) genes. The biochemical properties, expression, and function of the C. elegans SKR proteins were examined. RESULTS Of the 17 SKR proteins examined, eight (SKR-1, -2, -3, -4, -7, -8, -9, and -10) were shown to interact with C. elegans CUL1 by yeast two-hybrid analysis or a coimmunoprecipitation assay in mammalian cells. Furthermore, SKR proteins exhibited diverse binding specificities for C. elegans F-box proteins. The tissue specificity of expression of the CUL1-interacting SKR proteins was also varied. Suppression of skr-1 or skr-2 genes by double-stranded RNA interference resulted in embryonic death, whereas that of skr-7, -8, -9, or -10 was associated with slow growth and morphological abnormalities. CONCLUSIONS The multiple C. elegans SKR proteins exhibit marked differences in their association with Cullins and F-box proteins, in tissue specificity of expression, and in phenotypes associated with functional suppression by RNAi. At least eight of the SKR proteins may, like F-box proteins, act as variable components of the SCF complex in C. elegans.
Collapse
Affiliation(s)
- Atsushi Yamanaka
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, 812-8582, Fukuoka, Japan
| | | | | | | | | | | |
Collapse
|
172
|
del Pozo JC, Dharmasiri S, Hellmann H, Walker L, Gray WM, Estelle M. AXR1-ECR1-dependent conjugation of RUB1 to the Arabidopsis Cullin AtCUL1 is required for auxin response. THE PLANT CELL 2002; 14:421-33. [PMID: 11884684 PMCID: PMC152922 DOI: 10.1105/tpc.010282] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Mutations in the AXR1 gene result in a reduction in auxin response and diverse defects in auxin-regulated growth and development. In a previous study, we showed that AXR1 forms a heterodimer with the ECR1 protein. This enzyme activates the ubiquitin-related protein RUB1 in vitro. Furthermore, we showed that the Skp1-Cul1/Cdc53-F-box (SCF) subunit AtCUL1 is modified by RUB1 in vivo. In this report, we demonstrate that the formation of RUB-AtCUL1 is dependent on AXR1 and ECR1 in vivo. The expression of AXR1 and ECR1 is restricted to zones of active cell division and cell elongation, consistent with their role in growth regulation. These results provide strong support for a model in which RUB conjugation of AtCUL1 affects the function of SCF E3s that are required for auxin response.
Collapse
Affiliation(s)
- Juan C del Pozo
- Molecular Cell and Developmental Biology, Institute for Cellular and Molecular Biology, University of Texas at Austin, Texas 78712, USA
| | | | | | | | | | | |
Collapse
|
173
|
West CM, van der Wel H, Gaucher EA. Complex glycosylation of Skp1 in Dictyostelium: implications for the modification of other eukaryotic cytoplasmic and nuclear proteins. Glycobiology 2002; 12:17R-27R. [PMID: 11886837 DOI: 10.1093/glycob/12.2.17r] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Recently, complex O-glycosylation of the cytoplasmic/nuclear protein Skp1 has been characterized in the eukaryotic microorganism Dictyostelium. Skp1's glycosylation is mediated by the sequential action of a prolyl hydroxylase and five conventional sugar nucleotide-dependent glycosyltransferase activities that reside in the cytoplasm rather than the secretory compartment. The Skp1-HyPro GlcNAcTransferase, which adds the first sugar, appears to be related to a lineage of enzymes that originated in the prokaryotic cytoplasm and initiates mucin-type O-linked glycosylation in the lumen of the eukaryotic Golgi apparatus. GlcNAc is extended by a bifunctional glycosyltransferase that mediates the ordered addition of beta1,3-linked Gal and alpha1,2-linked Fuc. The architecture of this enzyme resembles that of certain two-domain prokaryotic glycosyltransferases. The catalytic domains are related to those of a large family of prokaryotic and eukaryotic, cytoplasmic, membrane-bound, inverting glycosyltransferases that modify glycolipids and polysaccharides prior to their translocation across membranes toward the secretory pathway or the cell exterior. The existence of these enzymes in the eukaryotic cytoplasm away from membranes and their ability to modify protein acceptors expose a new set of cytoplasmic and nuclear proteins to potential prolyl hydroxylation and complex O-linked glycosylation.
Collapse
Affiliation(s)
- Christopher M West
- Department of Anatomy and Cell Biology, 1600 SW Archer Road, University of Florida College of Medicine, Gainesville, FL 32610-0235, USA
| | | | | |
Collapse
|
174
|
Abstract
The plant hormone auxin is a simple molecule similar to tryptophan, yet it elicits a diverse array of responses and is involved in the regulation of growth and development throughout the plant life cycle. The ability of auxin to bring about such diverse responses appears to result partly from the existence of several independent mechanisms for auxin perception. Furthermore, one prominent mechanism for auxin signal transduction involves the targeted degradation of members of a large family of transcriptional regulators that appear to participate in complex and competing dimerization networks to modulate the expression of a wide range of genes. These models for auxin signaling now offer a framework in which to test how each specific response to auxin is brought about.
Collapse
Affiliation(s)
- Ottoline Leyser
- Department of Biology, University of York, York YO10 5YW, United Kingdom.
| |
Collapse
|
175
|
Rolland F, Moore B, Sheen J. Sugar sensing and signaling in plants. THE PLANT CELL 2002; 14 Suppl:S185-205. [PMID: 12045277 PMCID: PMC151255 DOI: 10.1105/tpc.010455] [Citation(s) in RCA: 610] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2001] [Accepted: 02/20/2002] [Indexed: 05/18/2023]
Affiliation(s)
| | | | - Jen Sheen
- To whom correspondence should be addressed. E-mail ; fax 617-726-6893
| |
Collapse
|
176
|
Abstract
Auxins are a class of phytohormones implicated in virtually every aspect of plant growth and development. Many early plant responses to auxin are apparently mediated by members of a family of Aux/IAA proteins that dimerize with and inhibit members of the auxin response factor (ARF) family of transcription factors. Aux/IAA proteins are unstable, and their degradation is triggered by a ubiquitin-protein ligase that is regulated by modification with a ubiquitin-related protein. Recent genetic and biochemical evidence indicates that auxin accelerates the degradation of the already short-lived Aux/IAA proteins to derepress transcription by ARF proteins. Several pieces of the auxin-signaling puzzle remain to be assembled, including the proteins that initially bind auxin, the proteins that convey this signal to the protein degradation machinery, and the targets of the transcriptional derepression.
Collapse
Affiliation(s)
- L E Rogg
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA
| | | |
Collapse
|
177
|
von Arnim AG. A hitchhiker's guide to the proteasome. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2001; 2001:pe2. [PMID: 11698580 DOI: 10.1126/stke.2001.97.pe2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Regulated degradation of proteins is essential for viability and is involved in the control of many signal transduction pathways. von Arnim discusses a new model for how substrates destined for degradation by the 26S proteasome may be presented to the proteasome through a physical interaction between the proteasome and a complex consisting of the substrate and a ubiquitin-ligase. The new model suggests that the SCF (Skp1/cullin/F-box) protein complex may physically associate with the proteasome and that this interaction may be regulated by posttranslational modifications, such as phosphorylation or the covalent attachment of the Nedd8 protein, called neddylation. Additionally, other proteins may compete with the SCF complexes for binding to the proteasome and thus present another layer of regulation for controlling substrate targeting for ubiquitin-mediated degradation.
Collapse
Affiliation(s)
- A G von Arnim
- Department of Botany, University of Tennessee, Knoxville, TN 37996-1100, USA.
| |
Collapse
|