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Campomenosi P, Mortara L, Bassani B, Valli R, Porta G, Bruno A, Acquati F. The Potential Role of the T2 Ribonucleases in TME-Based Cancer Therapy. Biomedicines 2023; 11:2160. [PMID: 37626657 PMCID: PMC10452627 DOI: 10.3390/biomedicines11082160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/23/2023] [Accepted: 07/24/2023] [Indexed: 08/27/2023] Open
Abstract
In recent years, there has been a growing interest in developing innovative anticancer therapies targeting the tumor microenvironment (TME). The TME is a complex and dynamic milieu surrounding the tumor mass, consisting of various cellular and molecular components, including those from the host organism, endowed with the ability to significantly influence cancer development and progression. Processes such as angiogenesis, immune evasion, and metastasis are crucial targets in the search for novel anticancer drugs. Thus, identifying molecules with "multi-tasking" properties that can counteract cancer cell growth at multiple levels represents a relevant but still unmet clinical need. Extensive research over the past two decades has revealed a consistent anticancer activity for several members of the T2 ribonuclease family, found in evolutionarily distant species. Initially, it was believed that T2 ribonucleases mainly acted as anticancer agents in a cell-autonomous manner. However, further investigation uncovered a complex and independent mechanism of action that operates at a non-cell-autonomous level, affecting crucial processes in TME-induced tumor growth, such as angiogenesis, evasion of immune surveillance, and immune cell polarization. Here, we review and discuss the remarkable properties of ribonucleases from the T2 family in the context of "multilevel" oncosuppression acting on the TME.
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Affiliation(s)
- Paola Campomenosi
- Laboratory of Molecular Genetics, Department of Biotechnology and Life Sciences, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy;
- Genomic Medicine Research Center, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy; (R.V.); (G.P.)
| | - Lorenzo Mortara
- Immunology and General Pathology Laboratory, Department of Biotechnology and Life Sciences, University of Insubria, Via Monte Generoso 71, 21100 Varese, Italy;
| | - Barbara Bassani
- Laboratory of Innate Immunity, Unit of Molecular Pathology, Biochemistry, and Immunology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) MultiMedica, Via G. Fantoli 16/15, 20138 Milan, Italy;
| | - Roberto Valli
- Genomic Medicine Research Center, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy; (R.V.); (G.P.)
- Department of Medicine and Surgery, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy
| | - Giovanni Porta
- Genomic Medicine Research Center, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy; (R.V.); (G.P.)
- Department of Medicine and Surgery, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy
| | - Antonino Bruno
- Immunology and General Pathology Laboratory, Department of Biotechnology and Life Sciences, University of Insubria, Via Monte Generoso 71, 21100 Varese, Italy;
- Laboratory of Innate Immunity, Unit of Molecular Pathology, Biochemistry, and Immunology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) MultiMedica, Via G. Fantoli 16/15, 20138 Milan, Italy;
| | - Francesco Acquati
- Genomic Medicine Research Center, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy; (R.V.); (G.P.)
- Human Genetics Laboratory, Department of Biotechnology and Life Sciences, University of Insubria, Via J.H. Dunant 3, 21100 Varese, Italy
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Thompson CE, Brisolara-Corrêa L, Thompson HN, Stassen H, de Freitas LB. Evolutionary and structural aspects of Solanaceae RNases T2. Genet Mol Biol 2022; 46:e20220115. [PMID: 36534953 PMCID: PMC9762611 DOI: 10.1590/1678-4685-gmb-2022-0115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 10/20/2022] [Indexed: 12/23/2022] Open
Abstract
Plant RNases T2 are involved in several physiological and developmental processes, including inorganic phosphate starvation, senescence, wounding, defense against pathogens, and the self-incompatibility system. Solanaceae RNases form three main clades, one composed exclusively of S-RNases and two that include S-like RNases. We identified several positively selected amino acids located in highly flexible regions of these molecules, mainly close to the B1 and B2 substrate-binding sites in S-like RNases and the hypervariable regions of S-RNases. These differences between S- and S-like RNases in the flexibility of amino acids in substrate-binding regions are essential to understand the RNA-binding process. For example, in the S-like RNase NT, two positively selected amino acid residues (Tyr156 and Asn134) are located at the most flexible sites on the molecular surface. RNase NT is induced in response to tobacco mosaic virus infection; these sites may thus be regions of interaction with pathogen proteins or viral RNA. Differential selective pressures acting on plant ribonucleases have increased amino acid variability and, consequently, structural differences within and among S-like RNases and S-RNases that seem to be essential for these proteins play different functions.
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Affiliation(s)
- Claudia Elizabeth Thompson
- Universidade Federal de Ciências da Saúde de Porto Alegre,
Departamento de Farmacociências, Porto Alegre, RS, Brazil
| | - Lauís Brisolara-Corrêa
- Universidade Federal do Rio Grande do Sul, Departamento de Genética,
Porto Alegre, RS, Brazil
| | - Helen Nathalia Thompson
- Universidade Federal do Rio Grande do Sul, Instituto de Química,
Departamento de Fisico-Química, Laboratório de Química Teórica e Computacional,
Porto Alegre, RS, Brazil
| | - Hubert Stassen
- Universidade Federal do Rio Grande do Sul, Instituto de Química,
Departamento de Fisico-Química, Laboratório de Química Teórica e Computacional,
Porto Alegre, RS, Brazil
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Torres-Rodríguez MD, González-Segura L, Rodríguez-Sotres R, Juárez-DíaZ JA, Cruz-Zamora Y, Cruz-García F. High resolution crystal structure of NaTrxh from Nicotiana alata and its interaction with the S-RNase. J Struct Biol 2020; 212:107578. [PMID: 32682729 DOI: 10.1016/j.jsb.2020.107578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/11/2020] [Accepted: 07/14/2020] [Indexed: 11/24/2022]
Abstract
Thioredoxins are regulatory proteins that reduce disulfide bonds on target proteins. NaTrxh, which belongs to the plant thioredoxin family h subgroup 2, interacts and reduces the S-RNase enhancing its ribonuclease activity seven-fold, resulting an essential protein for pollen rejection inNicotiana.Here, the crystal structure of NaTrxh at 1.7 Å by X-ray diffraction is reported. NaTrxh conserves the typical fold observed in other thioredoxins from prokaryotes and eukaryotes, but it contains extensions towards both N- and C-termini.The NaTrxh N-terminal extension participates in the reduction of S-RNase, and in the structure reported here, this is orientated towards the reactive site. The interaction between SF11-RNase and the NaTrxh N-terminal was simulated and the short-lived complex observed lasted for a tenth of ns. Moreover, we identified certain amino acids as SF11-RNase-E155 and NaTrxh-M104 as good candidates to contribute to the stability of the complex. Furthermore, we simulated the reduction of the C153-C186 SF11-RNase disulfide bond and observed subtle changes that affect the entire core, which might explain the increase in the ribonuclease activity of S-RNase when it is reduced by NaTrxh.
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Affiliation(s)
| | - Lilian González-Segura
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Cd. Mx 04510, Mexico
| | - Rogelio Rodríguez-Sotres
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Cd. Mx 04510, Mexico
| | - Javier Andrés Juárez-DíaZ
- Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Cd. Mx 04510, Mexico
| | - Yuridia Cruz-Zamora
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Cd. Mx 04510, Mexico
| | - Felipe Cruz-García
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Cd. Mx 04510, Mexico.
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Torres-Rodríguez MD, Cruz-Zamora Y, Juárez-Díaz JA, Mooney B, McClure BA, Cruz-García F. NaTrxh is an essential protein for pollen rejection in Nicotiana by increasing S-RNase activity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1304-1317. [PMID: 32392366 DOI: 10.1111/tpj.14802] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 03/20/2020] [Accepted: 04/28/2020] [Indexed: 06/11/2023]
Abstract
In self-incompatible Solanaceae, the pistil protein S-RNase contributes to S-specific pollen rejection in conspecific crosses, as well as to rejecting pollen from foreign species or whole clades. However, S-RNase alone is not sufficient for either type of pollen rejection. We describe a thioredoxin (Trx) type h from Nicotiana alata, NaTrxh, which interacts with and reduces S-RNase in vitro. Here, we show that expressing a redox-inactive mutant, NaTrxhSS , suppresses both S-specific pollen rejection and rejection of pollen from Nicotiana plumbaginifolia. Biochemical experiments provide evidence that NaTrxh specifically reduces the Cys155 -Cys185 disulphide bond of SC10 -Rnase, resulting in a significant increase of its ribonuclease activity. This reduction and increase in S-RNase activity by NaTrxh helps to explain why S-RNase alone could be insufficient for pollen rejection.
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Affiliation(s)
- Maria D Torres-Rodríguez
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México. Cd. Mx, 04510, México
| | - Yuridia Cruz-Zamora
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México. Cd. Mx, 04510, México
| | - Javier A Juárez-Díaz
- Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México. Cd. Mx, 04510, México
| | - Brian Mooney
- Charles W. Gehrke Proteomics Center, University of Missouri, Columbia, MO, 65211, USA
| | - Bruce A McClure
- Department of Biochemistry, University of Missouri, Columbia, MO, 65211, USA
| | - Felipe Cruz-García
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México. Cd. Mx, 04510, México
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5
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Miller JS, Blank CM, Levin RA. Colonization, Baker's law, and the evolution of gynodioecy in Hawaii: implications from a study of Lycium carolinianum. AMERICAN JOURNAL OF BOTANY 2019; 106:733-743. [PMID: 31042317 DOI: 10.1002/ajb2.1279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 03/06/2019] [Indexed: 06/09/2023]
Abstract
PREMISE As Baker's law suggests, the successful colonization of oceanic islands is often associated with uniparental reproduction (self-fertility), but the high incidence of dimorphism (dioecy, gynodioecy) on islands complicates this idea. Lycium carolinianum is widespread, occurring on the North American mainland and the Hawaiian Islands. We examined Baker's ideas for mainland and island populations of L. carolinianum and examined inbreeding depression as a possible contributor to the evolution of gynodioecy on Maui. METHODS Controlled crosses were conducted in two mainland populations and two populations in Hawaii. Treatments included self and cross pollination, unmanipulated controls, and autogamy/agamospermy. Alleles from the self-incompatibility S-RNase gene were isolated and compared between mainland and island populations. Given self-compatibility in Hawaii, we germinated seeds from self- and cross- treatments and estimated inbreeding depression using seven traits and a measure of cumulative fitness. RESULTS Mainland populations of Lycium carolinianum are predominately self-incompatible with some polymorphism for self-fertility, whereas Hawaiian populations are self-compatible. Concordantly, S-RNase allelic diversity is reduced in Hawaii compared to the mainland. Hawaiian populations also exhibit significant inbreeding depression. CONCLUSIONS Self-compatibility in Hawaii and individual variation in self-fertility in mainland populations suggests that a colonization filter promoting uniparental reproduction may be acting in this system. Comparison of S-RNase variation suggests a collapse of allelic diversity and heterozygosity at the S-RNase locus in Hawaii, which likely contributed to mate limitation upon arrival to the Pacific. Inbreeding depression coupled with autonomous self-fertilization may have led to the evolution of gynodioecy on Maui.
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Affiliation(s)
- Jill S Miller
- Department of Biology, Amherst College, Amherst, Massachusetts, 01002, USA
| | - Caitlin M Blank
- Department of Biology, Amherst College, Amherst, Massachusetts, 01002, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Rachel A Levin
- Department of Biology, Amherst College, Amherst, Massachusetts, 01002, USA
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Claessen H, Keulemans W, Van de Poel B, De Storme N. Finding a Compatible Partner: Self-Incompatibility in European Pear ( Pyrus communis); Molecular Control, Genetic Determination, and Impact on Fertilization and Fruit Set. FRONTIERS IN PLANT SCIENCE 2019; 10:407. [PMID: 31057563 PMCID: PMC6477101 DOI: 10.3389/fpls.2019.00407] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 03/18/2019] [Indexed: 05/25/2023]
Abstract
Pyrus species display a gametophytic self-incompatibility (GSI) system that actively prevents fertilization by self-pollen. The GSI mechanism in Pyrus is genetically controlled by a single locus, i.e., the S-locus, which includes at least two polymorphic and strongly linked S-determinant genes: a pistil-expressed S-RNase gene and a number of pollen-expressed SFBB genes (S-locus F-Box Brothers). Both the molecular basis of the SI mechanism and its functional expression have been widely studied in many Rosaceae fruit tree species with a particular focus on the characterization of the elusive SFBB genes and S-RNase alleles of economically important cultivars. Here, we discuss recent advances in the understanding of GSI in Pyrus and provide new insights into the mechanisms of GSI breakdown leading to self-fertilization and fruit set. Molecular analysis of S-genes in several self-compatible Pyrus cultivars has revealed mutations in both pistil- or pollen-specific parts that cause breakdown of self-incompatibility. This has significantly contributed to our understanding of the molecular and genetic mechanisms that underpin self-incompatibility. Moreover, the existence and development of self-compatible mutants open new perspectives for pear production and breeding. In this framework, possible consequences of self-fertilization on fruit set, development, and quality in pear are also reviewed.
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Affiliation(s)
- Hanne Claessen
- Laboratory for Plant Genetics and Crop Improvement, Division of Crop Biotechnics, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Wannes Keulemans
- Laboratory for Plant Genetics and Crop Improvement, Division of Crop Biotechnics, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Bram Van de Poel
- Laboratory for Molecular Plant Hormone Physiology, Division of Crop Biotechnics, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Nico De Storme
- Laboratory for Plant Genetics and Crop Improvement, Division of Crop Biotechnics, Department of Biosystems, KU Leuven, Leuven, Belgium
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7
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Li J, Zhang Y, Song Y, Zhang H, Fan J, Li Q, Zhang D, Xue Y. Electrostatic potentials of the S-locus F-box proteins contribute to the pollen S specificity in self-incompatibility in Petunia hybrida. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 89:45-57. [PMID: 27569591 DOI: 10.1111/tpj.13318] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 08/04/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
Self-incompatibility (SI) is a self/non-self discrimination system found widely in angiosperms and, in many species, is controlled by a single polymorphic S-locus. In the Solanaceae, Rosaceae and Plantaginaceae, the S-locus encodes a single S-RNase and a cluster of S-locus F-box (SLF) proteins to control the pistil and pollen expression of SI, respectively. Previous studies have shown that their cytosolic interactions determine their recognition specificity, but the physical force between their interactions remains unclear. In this study, we show that the electrostatic potentials of SLF contribute to the pollen S specificity through a physical mechanism of 'like charges repel and unlike charges attract' between SLFs and S-RNases in Petunia hybrida. Strikingly, the alteration of a single C-terminal amino acid of SLF reversed its surface electrostatic potentials and subsequently the pollen S specificity. Collectively, our results reveal that the electrostatic potentials act as a major physical force between cytosolic SLFs and S-RNases, providing a mechanistic insight into the self/non-self discrimination between cytosolic proteins in angiosperms.
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Affiliation(s)
- Junhui Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Yue Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Yanzhai Song
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Hui Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Jiangbo Fan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Qun Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
| | - Dongfen Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
| | - Yongbiao Xue
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing, 100101, China
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
- Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai, 200433, China
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8
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Dzidzienyo DK, Bryan GJ, Wilde G, Robbins TP. Allelic diversity of S-RNase alleles in diploid potato species. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2016; 129:1985-2001. [PMID: 27497984 PMCID: PMC5025496 DOI: 10.1007/s00122-016-2754-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 07/15/2016] [Indexed: 05/27/2023]
Abstract
The S-ribonuclease sequences of 16 S-alleles derived from diploid types of Solanum are presented. A phylogenetic analysis and partial phenotypic analysis support the conclusion that these are functional S-alleles. S-Ribonucleases (S-RNases) control the pistil specificity of the self-incompatibility (SI) response in the genus Solanum and several other members of the Solanaceae. The nucleotide sequences of S-RNases corresponding to a large number of S-alleles or S-haplotypes have been characterised. However, surprisingly, few S-RNase sequences are available for potato species. The identification of new S-alleles in diploid potato species is desirable as these stocks are important sources of traits such as biotic and abiotic resistance. S-RNase sequences are reported here from three distinct diploid types of potato: cultivated Solanum tuberosum Group Phureja, S. tuberosum Group Stenotomum, and the wild species Solanum okadae. Partial S-RNase sequences were obtained from pistil RNA by RT-PCR or 3'RACE (Rapid Amplification of cDNA Ends) using a degenerate primer. Full-length sequences were obtained for two alleles by 5'RACE. Database searches with these sequences identified 16 S-RNases in total, all of which are novel. The sequence analysis revealed all the expected features of functional S-RNases. Phylogenetic analysis with selected published S-RNase and S-like-RNase sequences from the Solanaceae revealed extensive trans-generic evolution of the S-RNases and a clear distinction from S-like-RNases. Pollination tests were used to confirm the self-incompatibility status and cross-compatibility relationships of the S. okadae accessions. All the S. okadae accessions were found to be self-incompatible as expected with crosses amongst them exhibiting both cross-compatibility and semi-compatibility consistent with the S-genotypes determined from the S-RNase sequence data. The progeny analysis of four semi-compatible crosses examined by allele-specific PCR provided further confirmation that these are functional S-RNases.
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Affiliation(s)
- Daniel K Dzidzienyo
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, Scotland, UK
- Biotechnology Centre, College of Basic and Applied Sciences, University of Ghana, P.O. Box LG 68, Legon-Accra, Ghana
| | - Glenn J Bryan
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, Scotland, UK
| | - Gail Wilde
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, Scotland, UK
| | - Timothy P Robbins
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK.
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Williams JS, Wu L, Li S, Sun P, Kao TH. Insight into S-RNase-based self-incompatibility in Petunia: recent findings and future directions. FRONTIERS IN PLANT SCIENCE 2015; 6:41. [PMID: 25699069 PMCID: PMC4318427 DOI: 10.3389/fpls.2015.00041] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/15/2015] [Indexed: 05/29/2023]
Abstract
S-RNase-based self-incompatibility in Petunia is a self/non-self recognition system that allows the pistil to reject self-pollen to prevent inbreeding and to accept non-self pollen for outcrossing. Cloning of S-RNase in 1986 marked the beginning of nearly three decades of intensive research into the mechanism of this complex system. S-RNase was shown to be the sole female determinant in 1994, and the first male determinant, S-locus F-box protein1 (SLF1), was identified in 2004. It was discovered in 2010 that additional SLF proteins are involved in pollen specificity, and recently two S-haplotypes of Petunia inflata were found to possess 17 SLF genes based on pollen transcriptome analysis, further increasing the complexity of the system. Here, we first summarize the current understanding of how the interplay between SLF proteins and S-RNase in the pollen tube allows cross-compatible pollination, but results in self-incompatible pollination. We then discuss some of the aspects that are not yet elucidated, including uptake of S-RNase into the pollen tube, nature, and assembly of SLF-containing complexes, the biochemical basis for differential interactions between SLF proteins and S-RNase, and fate of non-self S-RNases in the pollen tube.
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Affiliation(s)
- Justin S. Williams
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Lihua Wu
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
| | - Shu Li
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
| | - Penglin Sun
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
| | - Teh-Hui Kao
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
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10
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Brisolara-Corrêa L, Thompson CE, Fernandes CL, de Freitas LB. Diversification and distinctive structural features of S-RNase alleles in the genus Solanum. Mol Genet Genomics 2014; 290:987-1002. [PMID: 25501309 DOI: 10.1007/s00438-014-0969-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 11/27/2014] [Indexed: 11/29/2022]
Abstract
The multigenic and multiallelic S-locus in plants is responsible for the gametophytic self-incompatibility system, which is important to prevent the detrimental effects of self-fertilization and inbreeding depression. Several studies have discussed the importance of punctual mutations, recombination, and natural selection in the generation of allelic diversity in the S-locus. However, there has been no wide-ranging study correlating the molecular evolution and structural aspects of the corresponding proteins in Solanum. Therefore, we evaluated the molecular evolution of one gene in this locus and generated a statistically well-supported phylogenetic tree, as well as evidence of positive selection, helping us to understand the diversification of S alleles in Solanum. The three-dimensional structures of some of the proteins corresponding to the major clusters of the phylogenetic tree were constructed and subsequently submitted to molecular dynamics to stabilize the folding and obtain the native structure. The positively selected amino acid residues were predominantly located in the hyper variable regions and on the surface of the protein, which appears to be fundamental for allele specificity. One of the positively selected residues was identified adjacent to a conserved strand that is crucial for enzymatic catalysis. Additionally, we have shown significant differences in the electrostatic potential among the predicted molecular surfaces in S-RNases. The structural results indicate that local changes in the three-dimensional structure are present in some regions of the molecule, although the general structure seems to be conserved. No previous study has described such structural variations in S-RNases.
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Affiliation(s)
- Lauís Brisolara-Corrêa
- Department of Genetics, Laboratory of Molecular Evolution, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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11
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Krey T, Bontems F, Vonrhein C, Vaney MC, Bricogne G, Rümenapf T, Rey FA. Crystal structure of the pestivirus envelope glycoprotein E(rns) and mechanistic analysis of its ribonuclease activity. Structure 2012; 20:862-73. [PMID: 22579253 DOI: 10.1016/j.str.2012.03.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 02/29/2012] [Accepted: 03/03/2012] [Indexed: 01/24/2023]
Abstract
Pestiviruses, which belong to the Flaviviridae family of RNA viruses, are important agents of veterinary diseases causing substantial economical losses in animal farming worldwide. Pestivirus particles display three envelope glycoproteins at their surface: E(rns), E1, and E2. We report here the crystal structure of the catalytic domain of E(rns), the ribonucleolytic activity of which is believed to counteract the innate immunity of the host. The structure reveals a three-dimensional fold corresponding to T2 ribonucleases from plants and fungi. Cocrystallization experiments with mono- and oligonucleotides revealed the structural basis for substrate recognition at two binding sites previously identified for T2 RNases. A detailed analysis of poly-U cleavage products using (31)P-NMR and size exclusion chromatography, together with molecular docking studies, provides a comprehensive mechanistic picture of E(rns) activity on its substrates and reveals the presence of at least one additional nucleotide binding site.
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Affiliation(s)
- Thomas Krey
- Unité de Virologie Structurale, Institut Pasteur, 75015 Paris, France.
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12
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De Franceschi P, Dondini L, Sanzol J. Molecular bases and evolutionary dynamics of self-incompatibility in the Pyrinae (Rosaceae). JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:4015-32. [PMID: 22563122 DOI: 10.1093/jxb/ers108] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The molecular bases of the gametophytic self-incompatibility (GSI) system of species of the subtribe Pyrinae (Rosaceae), such as apple and pear, have been widely studied in the last two decades. The characterization of S-locus genes and of the mechanisms underlying pollen acceptance or rejection have been topics of major interest. Besides the single pistil-side S determinant, the S-RNase, multiple related S-locus F-box genes seem to be involved in the determination of pollen S specificity. Here, we collect and review the state of the art of GSI in the Pyrinae. We emphasize recent genomic data that have contributed to unveiling the S-locus structure of the Pyrinae, and discuss their consistency with the models of self-recognition that have been proposed for Prunus and the Solanaceae. Experimental data suggest that the mechanism controlling pollen-pistil recognition specificity of the Pyrinae might fit well with the collaborative 'non-self' recognition system proposed for Petunia (Solanaceae), whereas it presents relevant differences with the mechanism exhibited by the species of the closely related genus Prunus, which uses a single evolutionarily divergent F-box gene as the pollen S determinant. The possible involvement of multiple pollen S genes in the GSI system of Pyrinae, still awaiting experimental confirmation, opens up new perspectives to our understanding of the evolution of S haplotypes, and of the evolution of S-RNase-based GSI within the Rosaceae family. Whereas S-locus genes encode the players determining self-recognition, pollen rejection in the Pyrinae seems to involve a complex cascade of downstream cellular events with significant similarities to programmed cell death.
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Affiliation(s)
- Paolo De Franceschi
- Dipartimento di Colture Arboree (DCA), Università degli Studi di Bologna, Via Giuseppe Fanin 46, 40127 Bologna, Italy.
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13
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de Leeuw M, González A, Lanir A, Roiz L, Smirnoff P, Schwartz B, Shoseyov O, Almog O. The 1.8 Å Crystal Structure of ACTIBIND Suggests a Mode of Action for T2 Ribonucleases As Antitumorigenic Agents. J Med Chem 2012; 55:1013-20. [DOI: 10.1021/jm1015507] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marina de Leeuw
- Department of Clinical Biochemistry,
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Ana González
- Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, MS 99, Menlo
Park, California 94025, United States
| | - Assaf Lanir
- Department of Clinical Biochemistry,
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | | | | | | | | | - Orna Almog
- Department of Clinical Biochemistry,
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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14
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Abstract
BACKGROUND For the Solanaceae-type self-incompatibility, also possessed by Rosaceae and Plantaginaceae, the specificity of self/non-self interactions between pollen and pistil is controlled by two polymorphic genes at the S-locus: the S-locus F-box gene (SLF or SFB) controls pollen specificity and the S-RNase gene controls pistil specificity. SCOPE This review focuses on the work from the authors' laboratory using Petunia inflata (Solanaceae) as a model. Here, recent results on the identification and functional studies of S-RNase and SLF are summarized and a protein-degradation model is proposed to explain the biochemical mechanism for specific rejection of self-pollen tubes by the pistil. CONCLUSIONS The protein-degradation model invokes specific degradation of non-self S-RNases in the pollen tube mediated by an SLF, and can explain compatible versus incompatible pollination and the phenomenon of competitive interaction, where SI breaks down in pollen carrying two different S-alleles. In Solanaceae, Plantaginaceae and subfamily Maloideae of Rosaceae, there also exist multiple S-locus-linked SLF/SFB-like genes that potentially function as the pollen S-gene. To date, only three such genes, all in P. inflata, have been examined, and they do not function as the pollen S-gene in the S-genotype backgrounds tested. Interestingly, subfamily Prunoideae of Rosaceae appears to possess only a single SLF/SFB gene, and competitive interaction, observed in Solanaceae, Plantaginaceae and subfamily Maloideae, has not been observed. Thus, although the cytotoxic function of S-RNase is an integral part of SI in Solanaceae, Plantaginaceae and Rosaceae, the function of SLF/SFB may have diverged. This highlights the complexity of the S-RNase-based SI mechanism. The review concludes by discussing some key experiments that will further advance our understanding of this self/non-self discrimination mechanism.
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Affiliation(s)
- Xiaoying Meng
- Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Penglin Sun
- Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Teh-hui Kao
- Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
- For correspondence. E-mail
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15
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MacIntosh GC. RNase T2 Family: Enzymatic Properties, Functional Diversity, and Evolution of Ancient Ribonucleases. NUCLEIC ACIDS AND MOLECULAR BIOLOGY 2011. [DOI: 10.1007/978-3-642-21078-5_4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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16
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Miller JS, Kostyun JL. Functional gametophytic self-incompatibility in a peripheral population of Solanum peruvianum (Solanaceae). Heredity (Edinb) 2010; 107:30-9. [PMID: 21119705 DOI: 10.1038/hdy.2010.151] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The transition from self-incompatibility to self-compatibility is a common transition in angiosperms often reported in populations at the edge of species range limits. Geographically distinct populations of wild tomato species (Solanum section Lycopersicon (Solanaceae)) have been described as polymorphic for mating system with both self-incompatible and self-compatible populations. Using controlled pollinations and sequencing of the S-RNase mating system gene, we test the compatibility status of a population of S. peruvianum located near its southern range limit. Pollinations among plants of known genotypes revealed strong self-incompatibility; fruit set following compatible pollinations was significantly higher than following incompatible pollinations for all tested individuals. Sequencing of the S-RNase gene in parents and progeny arrays was also as predicted under self-incompatibility. Molecular variation at the S-RNase locus revealed a diverse set of alleles, and heterozygosity in over 500 genotyped individuals. We used controlled crosses to test the specificity of sequences recovered in this study; in all cases, results were consistent with a unique allelic specificity for each tested sequence, including two alleles sharing 92% amino-acid similarity. Site-specific patterns of selection at the S-RNase gene indicate positive selection in regions of the gene associated with allelic specificity determination and purifying selection in previously characterized conserved regions. Further, there is broad convergence between the present and previous studies in specific amino-acid positions inferred to be evolving under positive selection.
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Affiliation(s)
- J S Miller
- Department of Biology, Amherst College, MA, USA.
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17
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Protein interactions and subcellular localization in S-RNase-based self-incompatibility. Biochem Soc Trans 2010; 38:622-6. [DOI: 10.1042/bst0380622] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The recent identification of several proteins playing key roles in S-RNase-based gametophytic self-incompatibility has led both to a greater understanding of the molecular biology of this response, as well as to questions regarding the precise mechanism by which compatible pollen tubes are recognized and accepted. A proposed variant SCFSLF (where SCF is SSK1/cullin/F-box and SLF is S-locus F-box) ubiquitin ligase complex is thought to play a central role in recognizing and inhibiting non-self S-RNases, but the exact role of ubiquitination remains unclear. How the possible sequestration of non-self S-RNases in a pollen vacuolar compartment can be reconciled with the need for protein interaction between S-RNase and the SCFSLF complex needs to be determined. Current work to answer these questions focuses on more precisely defining quantitative protein interactions and subcellular localization of proteins involved in S-RNase-based gametophytic self-incompatibility.
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18
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Luhtala N, Parker R. T2 Family ribonucleases: ancient enzymes with diverse roles. Trends Biochem Sci 2010; 35:253-9. [PMID: 20189811 DOI: 10.1016/j.tibs.2010.02.002] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 02/02/2010] [Accepted: 02/03/2010] [Indexed: 01/27/2023]
Abstract
Ribonucleases of the T2 family are found in the genomes of protozoans, plants, bacteria, animals and viruses. A broad range of biological roles for these ribonucleases have been suggested, including scavenging of nucleic acids, degradation of self-RNA, serving as extra- or intracellular cytotoxins, and modulating host immune responses. Recently, RNaseT2 family members have been implicated in human pathologies such as cancer and parasitic diseases. Interestingly, certain functions of RNaseT2 family members are independent of their nuclease activity, suggesting that these proteins have additional functions. Moreover, humans lacking RNASET2 manifest a defect in neurological development, perhaps due to aberrant control of the immune system. We review the basic structure and function of RNaseT2 family members and their biological roles.
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Affiliation(s)
- Natalie Luhtala
- Cancer Biology Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ 85721-0106, USA
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19
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Li MF, Li XF, Han ZH, Shu HR, Li TZ. Molecular analysis of two Chinese pear (Pyrus bretschneideri Rehd.) spontaneous self-compatible mutants, Yan Zhuang and Jin Zhui. PLANT BIOLOGY (STUTTGART, GERMANY) 2009; 11:774-783. [PMID: 19689786 DOI: 10.1111/j.1438-8677.2008.00180.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Yan Zhuang and Jin Zhui are spontaneous bud mutants of Chinese pear (Pyrus bretschneideri Rehd.) from Ya Li. Both fruit set rate and seed number after self-pollination, together with pollen tube growth, prove that Yan Zhuang and Jin Zhui are self-compatible. The fruit set rate and seed number after cross-pollination suggest that the self-compatibility of Yan Zhuang and Jin Zhui may be due to natural mutations of the stylar S allele and pollen S allele, respectively. PCR amplification of the S-RNase gene in self-pollinated progeny of Yan Zhuang and Jin Zhui show that they contain point mutations in the stylar S(21) allele and pollen S(34) allele, respectively. The cDNA sequence of the Yan Zhuang stylar S-RNase gene revealed that the 182nd nucleotide of the S(21)-RNase (cDNA) sequence had been substituted resulting in a Gly to Val mutation, and this might affect the stability of the S-RNase. In addition, Western blotting showed that one Yan Zhuang stylar S-RNase was absent and the expression level of another S-RNase protein was decreased compared to Ya Li. Therefore, we suggest that the self-compatibility of Yan Zhuang is caused by a point mutation in an S(21)-RNase nucleotide.
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Affiliation(s)
- M F Li
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, China
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20
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McClure B. Darwin's foundation for investigating self-incompatibility and the progress toward a physiological model for S-RNase-based SI. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1069-1081. [PMID: 19297550 DOI: 10.1093/jxb/erp024] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Charles Darwin made extensive observations of the pollination biology of a wide variety of plants. He carefully documented the consequences of self-pollination and described species that were self-sterile but that could easily be crossed with other plants of the same species. He believed that compatibility was controlled by the 'mutual action' of pollen and pistil contents. A genetic model for self-sterility was developed in the early 1900 s based on studies of the compatibility relationships among, what are now referred to as, self-incompatible (SI) Nicotiana species. Today, it is believed that SI in these species is controlled by an interaction between S-RNases produced in the pistil and F-box proteins expressed in pollen and, moreover, that this S-RNase-based SI system is shared by a great diversity of other plant species. Current research is aimed at understanding how the mutual actions of these S-gene products function in the physiological context of pollen tube growth.
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Affiliation(s)
- Bruce McClure
- Division of Biochemistry, Interdisciplinary Plant Group, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211-7310, USA.
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21
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Rodriguez SM, Panjikar S, Van Belle K, Wyns L, Messens J, Loris R. Nonspecific base recognition mediated by water bridges and hydrophobic stacking in ribonuclease I from Escherichia coli. Protein Sci 2008; 17:681-90. [PMID: 18305191 PMCID: PMC2271172 DOI: 10.1110/ps.073420708] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 01/21/2008] [Accepted: 01/21/2008] [Indexed: 10/22/2022]
Abstract
The crystal structure of Escherichia coli ribonuclease I (EcRNase I) reveals an RNase T2-type fold consisting of a conserved core of six beta-strands and three alpha-helices. The overall architecture of the catalytic residues is very similar to the plant and fungal RNase T2 family members, but the perimeter surrounding the active site is characterized by structural elements specific for E. coli. In the structure of EcRNase I in complex with a substrate-mimicking decadeoxynucleotide d(CGCGATCGCG), we observe a cytosine bound in the B2 base binding site and mixed binding of thymine and guanine in the B1 base binding site. The active site residues His55, His133, and Glu129 interact with the phosphodiester linkage only through a set of water molecules. Residues forming the B2 base recognition site are well conserved among bacterial homologs and may generate limited base specificity. On the other hand, the B1 binding cleft acquires true base aspecificity by combining hydrophobic van der Waals contacts at its sides with a water-mediated hydrogen-bonding network at the bottom. This B1 base recognition site is highly variable among bacterial sequences and the observed interactions are unique to EcRNaseI and a few close relatives.
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Affiliation(s)
- Sergio Martinez Rodriguez
- Laboratorium voor Ultrastructuur, Vrije Universiteit Brussels, Pleinlaan 2, B-1050 Brussels, Belgium
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22
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Miller JS, Levin RA, Feliciano NM. A tale of two continents: Baker's rule and the maintenance of self-incompatibility in Lycium (Solanaceae). Evolution 2008; 62:1052-65. [PMID: 18315577 DOI: 10.1111/j.1558-5646.2008.00358.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Over 50 years ago, Baker (1955, 1967) suggested that self-compatible species were more likely than self-incompatible species to establish new populations on oceanic islands. His logic was straightforward and rested on the assumption that colonization was infrequent; thus, mate limitation favored the establishment of self-fertilizing individuals. In support of Baker's rule, many authors have documented high frequencies of self-compatibility on islands, and recent work has solidified the generality of Baker's ideas. The genus Lycium (Solanaceae) has ca. 80 species distributed worldwide, and phylogenetic studies suggest that Lycium originated in South America and dispersed to the Old World a single time. Previous analyses of the S-RNase gene, which controls the stylar component of self-incompatibility, have shown that gametophytically controlled self-incompatibility is ancestral within the genus, making Lycium a good model for investigating Baker's assertions concerning reproductive assurance following oceanic dispersal. Lycium is also useful for investigations of reproductive evolution, given that species vary both in sexual expression and the presence of self-incompatibility. A model for the evolution of gender dimorphism suggests that polyploidy breaks down self-incompatibility, leading to the evolution of gender dimorphism, which arises as an alternative outcrossing mechanism. There is a perfect association of dimorphic gender expression, polyploidy, and self-compatibility (vs. cosexuality, diploidy, and self-incompatibility) among North American Lycium. Although the association between ploidy level and gender expression also holds for African Lycium, to date no studies of mating systems have been initiated in Old World species. Here, using controlled pollinations, we document strong self-incompatibility in two cosexual, diploid species of African Lycium. Further, we sequence the S-RNase gene in 15 individuals from five cosexual, diploid species of African Lycium and recover 24 putative alleles. Genealogical analyses indicate reduced trans-generic diversity of S-RNases in the Old World compared to the New World. We suggest that genetic diversity at this locus was reduced as a result of a founder event, but, despite the bottleneck, self-incompatibility was maintained in the Old World. Maximum-likelihood analyses of codon substitution patterns indicate that positive Darwinian selection has been relatively strong in the Old World, suggesting the rediversification of S-RNases following a bottleneck. The present data thus provide a dramatic exception to Baker's rule, in addition to supporting a key assumption of the Miller and Venable (2000) model, namely that self-incompatibility is associated with diploidy and cosexuality.
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Affiliation(s)
- Jill S Miller
- Department of Biology, Amherst College, Amherst, MA 01002, USA.
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23
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Messens J, Collet JF, Van Belle K, Brosens E, Loris R, Wyns L. The Oxidase DsbA Folds a Protein with a Nonconsecutive Disulfide. J Biol Chem 2007; 282:31302-7. [PMID: 17702751 DOI: 10.1074/jbc.m705236200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the last unsolved problems of molecular biology is how the sequential amino acid information leads to a functional protein. Correct disulfide formation within a protein is hereby essential. We present periplasmic ribonuclease I (RNase I) from Escherichia coli as a new endogenous substrate for the study of oxidative protein folding. One of its four disulfides is between nonconsecutive cysteines. In general view, the folding of proteins with nonconsecutive disulfides requires the protein disulfide isomerase DsbC. In contrast, our study with RNase I shows that DsbA is a sufficient catalyst for correct disulfide formation in vivo and in vitro. DsbA is therefore more specific than generally assumed. Further, we show that the redox potential of the periplasm depends on the presence of glutathione and the Dsb proteins to maintain it at-165 mV. We determined the influence of this redox potential on the folding of RNase I. Under the more oxidizing conditions of dsb(-) strains, DsbC becomes necessary to correct non-native disulfides, but it cannot substitute for DsbA. Altogether, DsbA folds a protein with a nonconsecutive disulfide as long as no incorrect disulfides are formed.
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Affiliation(s)
- Joris Messens
- Brussels Center for Redox Biology, Vlaams Instituut voor Biotechnologie, Vrije Universiteit Brussel, 1050 Brussel, Belgium.
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24
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Igic B, Smith WA, Robertson KA, Schaal BA, Kohn JR. Studies of self-incompatibility in wild tomatoes: I. S-allele diversity in Solanum chilense (Dun.) Reiche [corrected] (Solanaceae). Heredity (Edinb) 2007; 99:553-61. [PMID: 17700636 DOI: 10.1038/sj.hdy.6801035] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We characterized the molecular allelic variation of RNases at the self-incompatibility (SI) locus of Solanum chilense Dun. We recovered 30 S-RNase allele sequences from 34 plants representing a broad geographic sample. This yielded a species-wide estimate of 35 (95% likelihood interval 31-40) S-alleles. We performed crosses to confirm the association with SI function of 10 of the putative S-RNase allele sequences. Results in all cases were consistent with the expectation that these sequences represent functional alleles under single-locus gametophytic SI. We used the allele sequences to conduct an analysis of selection, as measured by the excess of nonsynonymous changes per site, and found evidence for adaptive changes both within the traditionally defined hypervariable regions and downstream, near the 3'-end of the molecule.
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Affiliation(s)
- B Igic
- Department of Biological Sciences, University of Illinois-Chicago, Chicago, IL 60607, USA.
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25
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Savage AE, Miller JS. Gametophytic self-incompatibility in Lycium parishii (Solanaceae): allelic diversity, genealogical structure, and patterns of molecular evolution at the S-RNase locus. Heredity (Edinb) 2006; 96:434-44. [PMID: 16622475 DOI: 10.1038/sj.hdy.6800818] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We characterized allelic diversity at the locus controlling self-incompatibility (SI) for a population of Lycium parishii (Solanaceae) from Organ Pipe National Monument, Arizona. Twenty-four partial sequences of S-RNase alleles were recovered from 25 individuals. Estimates of allelic diversity range from 23 to 27 alleles and, consistent with expectations for SI, individuals are heterozygous. We compare S-RNase diversity, patterns of molecular evolution, and the genealogical structure of alleles from L. parishii to a previously studied population of its congener L. andersonii. Gametophytic SI is well characterized for Solanaceae and although balancing selection is hypothesized to be responsible for high levels of allelic divergence, the pattern of selection varies depending on the portion of the gene considered. Site-specific models investigating patterns of selection for L. parishii and L. andersonii indicate that positive selection occurs in those regions of the S-RNase gene hypothesized as important to the recognition response, whereas positive selection was not detected for any position within regions previously characterized as conserved. A 10-species genealogy including S-RNases from a pair of congeners from each of five genera in Solanaceae reveals extensive transgeneric evolution of L. parishii S-RNases. Further, within Lycium, the Dn/Ds ratios for pairs of closely related alleles for intraspecific versus interspecific comparisons were not significantly different, suggesting that the S-RNase diversity recovered in these two species was present prior to the speciation event separating them. Despite this, two S-RNases from L. parishii are identical to two previously reported alleles for L. andersonii, suggesting gene flow between these species.
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Affiliation(s)
- A E Savage
- Department of Biology, Amherst College, McGuire Life Sciences Building, Amherst, MA 01002, USA
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26
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Qin X, Soulard J, Laublin G, Morse D, Cappadocia M. Molecular analysis of the conserved C4 region of the S11-RNase of Solanum chacoense. PLANTA 2005; 221:531-537. [PMID: 15650838 DOI: 10.1007/s00425-004-1470-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Accepted: 12/01/2004] [Indexed: 05/24/2023]
Abstract
The stylar component to gametophytic self-incompatibility in Solanaceae is an S-RNase. Its primary structure has a characteristic pattern of two hypervariable regions, involved in pollen recognition, and five constant regions. Two of the latter (C2 and C3) constitute the active site, while the highly hydrophobic C1 and C5 are believed to be involved in protein stability. We analyzed the role of the C4 region by site-directed mutagenesis. A GGGG mutant, in which the four charged residues in the C4 region were replaced with glycine, did not accumulate the protein to detectable levels in styles, suggestive of a role in protein stability. A R115G mutant, in which a charged amino acid was eliminated to reduce the potential binding affinity, had no effect on the pollen rejection phenotype. This suggests the C4 does not interact with partners such as potential pollen tube receptors facilitating S-RNase uptake. Finally, a K113R mutant replaced a potential ubiquitination target with arginine. However, this RNase acted as the wild type in both incompatible and compatible crosses. The latter crosses rule out the role of the conserved C4 lysine in ubiquitination.
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Affiliation(s)
- Xike Qin
- IRBV, Biology Department, University of Montreal, 4101 rue Sherbrooke est, Montreal, Canada, H1X 2B2
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27
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Cruz-Garcia F, Nathan Hancock C, Kim D, McClure B. Stylar glycoproteins bind to S-RNase in vitro. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 42:295-304. [PMID: 15842616 DOI: 10.1111/j.1365-313x.2005.02375.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
S-RNases determine the specificity of S-specific pollen rejection in self-incompatible plants of the Solanaceae, Rosaceae, and Scrophulariaceae. They are also implicated in at least two distinct types of unilateral interspecific incompatibility in Nicotiana. However, S-RNase itself is not sufficient for most types of pollen rejection, and evidence for its direct interaction with pollen tubes is limited. Thus, non-S-RNase factors also are required for pollen rejection. As one approach to identifying such factors, we tested whether SC10-RNase from Nicotiana alata would bind to other stylar proteins in vitro. SC10-RNase was immobilized on Affi-gel, and binding proteins were analyzed by SDS-PAGE and immunoblotting. In addition to SC10-RNase and a small protein similar to lily chemocyanin, the most prominent binding proteins include NaTTS, 120K, and NaPELPIII, these latter three being arabinogalactan proteins previously shown to interact directly with pollen tubes. We also show that SC10-RNase and these glycoproteins migrate as a complex in a native PAGE system. Our hypothesis is that S-RNase forms a complex with these glycoproteins in the stylar ECM, that the glycoproteins interact directly with the pollen tubes and thus that the initial interaction between the pollen tube and S-RNase is indirect.
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Affiliation(s)
- Felipe Cruz-Garcia
- Department of Biochemistry, University of Missouri-Columbia, 117 Schweitzer Hall, Columbia, MO 65211, USA
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28
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Abstract
Sexual reproduction in many flowering plants involves self-incompatibility (SI), which is one of the most important systems to prevent inbreeding. In many species, the self-/nonself-recognition of SI is controlled by a single polymorphic locus, the S-locus. Molecular dissection of the S-locus revealed that SI represents not one system, but a collection of divergent mechanisms. Here, we discuss recent advances in the understanding of three distinct SI mechanisms, each controlled by two separate determinant genes at the S-locus. In the Brassicaceae, the determinant genes encode a pollen ligand and its stigmatic receptor kinase; their interaction induces incompatible signaling(s) within the stigma papilla cells. In the Solanaceae-type SI, the determinants are a ribonuclease and an F-box protein, suggesting the involvement of RNA and protein degradation in the system. In the Papaveraceae, the only identified female determinant induces a Ca2+-dependent signaling network that ultimately results in the death of incompatible pollen.
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Affiliation(s)
- Seiji Takayama
- Laboratory of Intercellular Communications, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
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29
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Mueller JL, Ripoll DR, Aquadro CF, Wolfner MF. Comparative structural modeling and inference of conserved protein classes in Drosophila seminal fluid. Proc Natl Acad Sci U S A 2004; 101:13542-7. [PMID: 15345744 PMCID: PMC518759 DOI: 10.1073/pnas.0405579101] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Indexed: 11/18/2022] Open
Abstract
The constituents of seminal fluid are a complex mixture of proteins and other molecules, most of whose functions have yet to be determined and many of which are rapidly evolving. As a step in elucidating the roles of these proteins and exposing potential functional similarities hidden by their rapid evolution, we performed comparative structural modeling on 28 of 52 predicted seminal proteins produced in the Drosophila melanogaster male accessory gland. Each model was characterized by defining residues likely to be important for structure and function. Comparisons of known protein structures with predicted accessory gland proteins (Acps) revealed similarities undetectable by primary sequence alignments. The structures predict that Acps fall into several categories: regulators of proteolysis, lipid modifiers, immunity/protection, sperm-binding proteins, and peptide hormones. The comparative structural modeling approach indicates that major functional classes of mammalian and Drosophila seminal fluid proteins are conserved, despite differences in reproductive strategies. This is particularly striking in the face of the rapid protein sequence evolution that characterizes many reproductive proteins, including Drosophila and mammalian seminal proteins.
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Affiliation(s)
- Jacob L Mueller
- Department of Molecular Biology and Genetics, Biotechnology Building, Cornell Theory Center, Cornell University, Ithaca, NY 14853, USA
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Gan JH, Yu L, Wu J, Xu H, Choudhary JS, Blackstock WP, Liu WY, Xia ZX. The three-dimensional structure and X-ray sequence reveal that trichomaglin is a novel S-like ribonuclease. Structure 2004; 12:1015-25. [PMID: 15274921 DOI: 10.1016/j.str.2004.03.023] [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: 01/20/2004] [Revised: 02/26/2004] [Accepted: 03/27/2004] [Indexed: 11/27/2022]
Abstract
Trichomaglin is a protein isolated from root tuber of the plant Maganlin (Trichosanthes Lepiniate, Cucurbitaceae). The crystal structure of trichomaglin has been determined by multiple-isomorphous replacement and refined at 2.2 A resolution. The X-ray sequence was established, based on electron density combined with the experimentally determined N-terminal sequence, and the sequence information derived from mass spectroscopic analysis. X-ray sequence-based homolog search and the three-dimensional structure reveal that trichomaglin is a novel S-like RNase, which was confirmed by biological assay. Trichomaglin molecule contains an additional beta sheet in the HV(b) region, compared with the known plant RNase structures. Fourteen cystein residues form seven disulfide bridges, more than those in the other known structures of S- and S-like RNases. His43 and His105 are expected to be the catalytic acid and base, respectively. Four hydrosulfate ions are bound in the active site pocket, three of them mimicking the substrate binding sites.
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Affiliation(s)
- Jian-Hua Gan
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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Isolation of S-RNase binding proteins from Solanum chacoense: identification of an SBP1 (RING finger protein) orthologue. ACTA ACUST UNITED AC 2004. [DOI: 10.1007/s00497-004-0218-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Franklin-Tong NVE, Franklin FCH. Gametophytic self-incompatibility inhibits pollen tube growth using different mechanisms. TRENDS IN PLANT SCIENCE 2003; 8:598-605. [PMID: 14659709 DOI: 10.1016/j.tplants.2003.10.008] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Self-incompatibility (SI) is one of the most important mechanisms used by plants to prevent self-pollination and consequently inbreeding. It is genetically controlled by the S-locus, which allows the recognition and rejection of 'self' (S-phenotypically identical) pollen. Gametophytically controlled SI (GSI) is the most widespread SI system. To date, only two forms have been elucidated in detail at the molecular level, revealing two different stigmatic S-genes. Here we summarize the evidence for the use of two different mechanisms to inhibit incompatible pollen tube growth. Because the limited data suggest the independent evolution of these two GSI systems, it would be interesting to explore other GSI systems to determine the extent of the mechanistic diversity.
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Entani T, Iwano M, Shiba H, Che FS, Isogai A, Takayama S. Comparative analysis of the self-incompatibility (S-) locus region of Prunus mume: identification of a pollen-expressed F-box gene with allelic diversity. Genes Cells 2003; 8:203-13. [PMID: 12622718 DOI: 10.1046/j.1365-2443.2003.00626.x] [Citation(s) in RCA: 248] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Self-incompatibility (SI) in the Solanaceae, Rosaceae and Scrophulariaceae is gametophytically controlled by a single polymorphic locus, termed the S-locus. To date, the only known S-locus product is a polymorphic ribonuclease, termed S-RNase, which is secreted by stylar tissue and thought to act as a cytotoxin that degrades the RNA of incompatible pollen tubes. However, understanding how S-RNase causes S-haplotype specific inhibition of pollen tubes has been hampered by the lack of a cloned pollen S-determinant gene. RESULTS To identify the pollen S-determinant gene, we investigated the genomic structure of the S-locus region of the S1- and S7-haplotypes of Prunus mume (Japanese apricot), and identified 13 genes around the S-RNase gene. Among them, only one F-box gene, termed SLF (S-locus F-box), fulfilled the conditions for a pollen S-determinant gene: (i) together with the S-RNase gene, it is located within the highly divergent genomic region of the S-locus, (ii) it exhibits S-haplotype specific diversity among three analysed S-haplotypes, and (iii) it is specifically expressed in pollen, but not in the styles or leaves. CONCLUSION The results indicate that SLF is a prime candidate for the pollen S-determinant gene of SI.
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Affiliation(s)
- Tetsuyuki Entani
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0101, Japan
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Wang Y, Wang X, Skirpan AL, Kao TH. S-RNase-mediated self-incompatibility. JOURNAL OF EXPERIMENTAL BOTANY 2003; 54:115-122. [PMID: 12456761 DOI: 10.1093/jxb/erg008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The Solanaceae, Rosaceae, and Scrophulariaceae families all possess an RNase-mediated self-incompatibility mechanism through which their pistils can recognize and reject self-pollen to prevent inbreeding. The highly polymorphic S-locus controls the self-incompatibility interaction, and the S-locus of the Solanaceae has been shown to be a multi-gene complex in excess of 1.3 Mb. To date, the function of only one of the S-locus genes, the S-RNase gene, has been determined. This article reviews the current status of the search for the pollen S-gene and the current models for how S-haplotype specific inhibition of pollen tubes can be accomplished by S-RNases.
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Affiliation(s)
- Yan Wang
- Intercollege Graduate Degree Program in Plant Physiology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Cruz-Garcia F, Hancock CN, McClure B. S-RNase complexes and pollen rejection. JOURNAL OF EXPERIMENTAL BOTANY 2003; 54:123-30. [PMID: 12456762 DOI: 10.1093/jxb/erg045] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Biochemical interactions between the pollen and the pistil allow plants fine control over fertilization. S-RNase-based pollen rejection is among the most widespread and best understood of these interactions. At least three plant families have S-RNase-based self-incompatibility (SI) systems, and S-RNases have also been implicated in interspecific pollen rejection. Although S-RNases determine the specificity of SI, other genes are required for the pollen rejection system to function. Progress is being made toward identifying these non-S-RNase factors. HT-protein, first identified as a non-S-RNase factor that was required for SI in Nicotiana alata, has now been implicated in other species as well. In addition, several pistil proteins bind to S-RNase in vitro. One hypothesis is that S-RNase forms a complex with these proteins in vivo that is the active form of S-RNase in pollen rejection.
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Affiliation(s)
- Felipe Cruz-Garcia
- Department of Biochemistry, Facultad de Química, National Autonomous University of México, Conjunto 'E' Paseo de la Investigacio'n Cientifica, Ciudad Universitaria, 04510 México DF, México
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Abstract
Plant self-incompatibility (SI) systems are unique among self/nonself recognition systems in being based on the recognition of self rather than nonself. SI in crucifer species is controlled by highly polymorphic and co-evolving genes linked in a complex. Self recognition is based on allele-specific interactions between stigma receptors and pollen ligands that result in the arrest of pollen tube development. Commonalities and differences between SI and other self/nonself discrimination systems are discussed.
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Affiliation(s)
- June B Nasrallah
- Department of Plant Biology, Cornell University, Ithaca, NY 14853, USA.
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