1
|
Barela Hudgell MA, Momtaz F, Jafri A, Alekseyev MA, Smith LC. Local Genomic Instability of the SpTransformer Gene Family in the Purple Sea Urchin Inferred from BAC Insert Deletions. Genes (Basel) 2024; 15:222. [PMID: 38397211 PMCID: PMC10887614 DOI: 10.3390/genes15020222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
The SpTransformer (SpTrf) gene family in the purple sea urchin, Strongylocentrotus purpuratus, encodes immune response proteins. The genes are clustered, surrounded by short tandem repeats, and some are present in genomic segmental duplications. The genes share regions of sequence and include repeats in the coding exon. This complex structure is consistent with putative local genomic instability. Instability of the SpTrf gene cluster was tested by 10 days of growth of Escherichia coli harboring bacterial artificial chromosome (BAC) clones of sea urchin genomic DNA with inserts containing SpTrf genes. After the growth period, the BAC DNA inserts were analyzed for size and SpTrf gene content. Clones with multiple SpTrf genes showed a variety of deletions, including loss of one, most, or all genes from the cluster. Alternatively, a BAC insert with a single SpTrf gene was stable. BAC insert instability is consistent with variations in the gene family composition among sea urchins, the types of SpTrf genes in the family, and a reduction in the gene copy number in single coelomocytes. Based on the sequence variability among SpTrf genes within and among sea urchins, local genomic instability of the family may be important for driving sequence diversity in this gene family that would be of benefit to sea urchins in their arms race with marine microbes.
Collapse
Affiliation(s)
- Megan A. Barela Hudgell
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
| | - Farhana Momtaz
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
| | - Abiha Jafri
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
| | - Max A. Alekseyev
- Department of Mathematics and the Computational Biology Institute, George Washington University, Washington, DC 20052, USA;
| | - L. Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
| |
Collapse
|
2
|
Clavé C, Dheur S, Ament-Velásquez SL, Granger-Farbos A, Saupe SJ. het-B allorecognition in Podospora anserina is determined by pseudo-allelic interaction of genes encoding a HET and lectin fold domain protein and a PII-like protein. PLoS Genet 2024; 20:e1011114. [PMID: 38346076 PMCID: PMC10890737 DOI: 10.1371/journal.pgen.1011114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/23/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024] Open
Abstract
Filamentous fungi display allorecognition genes that trigger regulated cell death (RCD) when strains of unlike genotype fuse. Podospora anserina is one of several model species for the study of this allorecognition process termed heterokaryon or vegetative incompatibility. Incompatibility restricts transmission of mycoviruses between isolates. In P. anserina, genetic analyses have identified nine incompatibility loci, termed het loci. Here we set out to clone the genes controlling het-B incompatibility. het-B displays two incompatible alleles, het-B1 and het-B2. We find that the het-B locus encompasses two adjacent genes, Bh and Bp that exist as highly divergent allelic variants (Bh1/Bh2 and Bp1/Bp2) in the incompatible haplotypes. Bh encodes a protein with an N-terminal HET domain, a cell death inducing domain bearing homology to Toll/interleukin-1 receptor (TIR) domains and a C-terminal domain with a predicted lectin fold. The Bp product is homologous to PII-like proteins, a family of small trimeric proteins acting as sensors of adenine nucleotides in bacteria. We show that although the het-B system appears genetically allelic, incompatibility is in fact determined by the non-allelic Bh1/Bp2 interaction while the reciprocal Bh2/Bp1 interaction plays no role in incompatibility. The highly divergent C-terminal lectin fold domain of BH determines recognition specificity. Population studies and genome analyses indicate that het-B is under balancing selection with trans-species polymorphism, highlighting the evolutionary significance of the two incompatible haplotypes. In addition to emphasizing anew the central role of TIR-like HET domains in fungal RCD, this study identifies novel players in fungal allorecognition and completes the characterization of the entire het gene set in that species.
Collapse
Affiliation(s)
- Corinne Clavé
- IBGC, UMR 5095, CNRS-Université de Bordeaux, Bordeaux, France
| | - Sonia Dheur
- IBGC, UMR 5095, CNRS-Université de Bordeaux, Bordeaux, France
| | | | | | - Sven J. Saupe
- IBGC, UMR 5095, CNRS-Université de Bordeaux, Bordeaux, France
| |
Collapse
|
3
|
Abstract
Investigation of fungal biology has been frequently motivated by the fact that many fungal species are important plant and animal pathogens. Such efforts have contributed significantly toward our understanding of fungal pathogenic lifestyles (virulence factors and strategies) and the interplay with host immune systems. In parallel, work on fungal allorecognition systems leading to the characterization of fungal regulated cell death determinants and pathways, has been instrumental for the emergent concept of fungal immunity. The uncovered evolutionary trans-kingdom parallels between fungal regulated cell death pathways and innate immune systems incite us to reflect further on the concept of a fungal immune system. Here, I briefly review key findings that have shaped the fungal immunity paradigm, providing a perspective on what I consider its most glaring knowledge gaps. Undertaking to fill such gaps would establish firmly the fungal immune system inside the broader field of comparative immunology.
Collapse
Affiliation(s)
- Asen Daskalov
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- ImmunoConcEpT, CNRS UMR 5164, University of Bordeaux, Bordeaux, France
| |
Collapse
|
4
|
Wojciechowski JW, Tekoglu E, Gąsior-Głogowska M, Coustou V, Szulc N, Szefczyk M, Kopaczyńska M, Saupe SJ, Dyrka W. Exploring a diverse world of effector domains and amyloid signaling motifs in fungal NLR proteins. PLoS Comput Biol 2022; 18:e1010787. [PMID: 36542665 PMCID: PMC9815663 DOI: 10.1371/journal.pcbi.1010787] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 01/05/2023] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
NLR proteins are intracellular receptors constituting a conserved component of the innate immune system of cellular organisms. In fungi, NLRs are characterized by high diversity of architectures and presence of amyloid signaling. Here, we explore the diverse world of effector and signaling domains of fungal NLRs using state-of-the-art bioinformatic methods including MMseqs2 for fast clustering, probabilistic context-free grammars for sequence analysis, and AlphaFold2 deep neural networks for structure prediction. In addition to substantially improving the overall annotation, especially in basidiomycetes, the study identifies novel domains and reveals the structural similarity of MLKL-related HeLo- and Goodbye-like domains forming the most abundant superfamily of fungal NLR effectors. Moreover, compared to previous studies, we found several times more amyloid motif instances, including novel families, and validated aggregating and prion-forming properties of the most abundant of them in vitro and in vivo. Also, through an extensive in silico search, the NLR-associated amyloid signaling was identified in basidiomycetes. The emerging picture highlights similarities and differences in the NLR architectures and amyloid signaling in ascomycetes, basidiomycetes and other branches of life.
Collapse
Affiliation(s)
- Jakub W. Wojciechowski
- Katedra Inżynierii Biomedycznej, Wydział Podstawowych Problemów Techniki, Politechnika Wrocławska, Wrocław, Poland
| | - Emirhan Tekoglu
- Biyomühendislik Bölümü, Yıldız Teknik Üniversitesi, İstanbul, Turkey
- Wydział Chemiczny, Politechnika Wrocławska, Poland
| | - Marlena Gąsior-Głogowska
- Katedra Inżynierii Biomedycznej, Wydział Podstawowych Problemów Techniki, Politechnika Wrocławska, Wrocław, Poland
| | - Virginie Coustou
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, Bordeaux, France
| | - Natalia Szulc
- Katedra Inżynierii Biomedycznej, Wydział Podstawowych Problemów Techniki, Politechnika Wrocławska, Wrocław, Poland
| | - Monika Szefczyk
- Katedra Chemii Bioorganicznej, Wydział Chemiczny, Politechnika Wrocławska, Wrocław, Poland
| | - Marta Kopaczyńska
- Katedra Inżynierii Biomedycznej, Wydział Podstawowych Problemów Techniki, Politechnika Wrocławska, Wrocław, Poland
| | - Sven J. Saupe
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, Bordeaux, France
- * E-mail: (SJS); (WD)
| | - Witold Dyrka
- Katedra Inżynierii Biomedycznej, Wydział Podstawowych Problemów Techniki, Politechnika Wrocławska, Wrocław, Poland
- * E-mail: (SJS); (WD)
| |
Collapse
|
5
|
Ament-Velásquez SL, Vogan AA, Granger-Farbos A, Bastiaans E, Martinossi-Allibert I, Saupe SJ, de Groot S, Lascoux M, Debets AJM, Clavé C, Johannesson H. Allorecognition genes drive reproductive isolation in Podospora anserina. Nat Ecol Evol 2022; 6:910-923. [PMID: 35551248 PMCID: PMC9262711 DOI: 10.1038/s41559-022-01734-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 03/15/2022] [Indexed: 11/09/2022]
Abstract
Allorecognition, the capacity to discriminate self from conspecific non-self, is a ubiquitous organismal feature typically governed by genes evolving under balancing selection. Here, we show that in the fungus Podospora anserina, allorecognition loci controlling vegetative incompatibility (het genes), define two reproductively isolated groups through pleiotropic effects on sexual compatibility. These two groups emerge from the antagonistic interactions of the unlinked loci het-r (encoding a NOD-like receptor) and het-v (encoding a methyltransferase and an MLKL/HeLo domain protein). Using a combination of genetic and ecological data, supported by simulations, we provide a concrete and molecularly defined example whereby the origin and coexistence of reproductively isolated groups in sympatry is driven by pleiotropic genes under balancing selection.
Collapse
Affiliation(s)
- S Lorena Ament-Velásquez
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, Sweden. .,Department of Zoology, Stockholm University, Stockholm, Sweden.
| | - Aaron A Vogan
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, Sweden
| | - Alexandra Granger-Farbos
- Institut de Biochimie et de Génétique Cellulaires, UMR 5095, CNRS, Université de Bordeaux, Bordeaux, France
| | - Eric Bastiaans
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, Sweden.,Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Ivain Martinossi-Allibert
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, Sweden.,Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Sven J Saupe
- Institut de Biochimie et de Génétique Cellulaires, UMR 5095, CNRS, Université de Bordeaux, Bordeaux, France
| | - Suzette de Groot
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Martin Lascoux
- Plant Ecology and Evolution, Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Alfons J M Debets
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Corinne Clavé
- Institut de Biochimie et de Génétique Cellulaires, UMR 5095, CNRS, Université de Bordeaux, Bordeaux, France
| | - Hanna Johannesson
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, Sweden.
| |
Collapse
|
6
|
Deryusheva EI, Machulin AV, Galzitskaya OV. Structural, Functional, and Evolutionary Characteristics of Proteins with Repeats. Mol Biol 2021. [DOI: 10.1134/s0026893321040038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
7
|
Dyrka W, Coustou V, Daskalov A, Lends A, Bardin T, Berbon M, Kauffmann B, Blancard C, Salin B, Loquet A, Saupe SJ. Identification of NLR-associated Amyloid Signaling Motifs in Bacterial Genomes. J Mol Biol 2020; 432:6005-6027. [PMID: 33058872 DOI: 10.1016/j.jmb.2020.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 10/05/2020] [Accepted: 10/05/2020] [Indexed: 02/06/2023]
Abstract
In filamentous fungi, amyloid signaling sequences allow Nod-like receptors (NLRs) to activate downstream cell-death inducing proteins with HeLo and HeLo-like (HELL) domains and amyloid RHIM and RHIM-related motifs control immune defense pathways in mammals and flies. Herein, we show bioinformatically that analogous amyloid signaling motifs exist in bacteria. These short motifs are found at the N terminus of NLRs and at the C terminus of proteins with a domain we term BELL. The corresponding NLR and BELL proteins are encoded by adjacent genes. We identify 10 families of such bacterial amyloid signaling sequences (BASS), one of which (BASS3) is homologous to RHIM and a fungal amyloid motif termed PP. BASS motifs occur nearly exclusively in bacteria forming multicellular structures (mainly in Actinobacteria and Cyanobacteria). We analyze experimentally a subset of seven of these motifs (from the most common BASS1 family and the RHIM-related BASS3 family) and find that these sequences form fibrils in vitro. Using a fungal in vivo model, we show that all tested BASS-motifs form prions and that the NLR-side motifs seed prion-formation of the corresponding BELL-side motif. We find that BASS3 motifs show partial prion cross-seeding with mammalian RHIM and fungal PP-motifs and that proline mutations on key positions of the BASS3 core motif, conserved in RHIM and PP-motifs, abolish prion formation. This work expands the paradigm of prion amyloid signaling to multicellular prokaryotes and suggests a long-term evolutionary conservation of these motifs from bacteria, to fungi and animals.
Collapse
Affiliation(s)
- Witold Dyrka
- Politechnika Wrocławska, Wydział Podstawowych Problemów Techniki, Katedra Inżynierii Biomedycznej, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Virginie Coustou
- Non-self Recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, 1 Rue Camille Saint Saëns, 33077 Bordeaux CEDEX, France
| | - Asen Daskalov
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248 CBMN, IECB, CNRS, Université de Bordeaux, Allee Geoffroy Saint-Hilaire, 33607 Pessac, France
| | - Alons Lends
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248 CBMN, IECB, CNRS, Université de Bordeaux, Allee Geoffroy Saint-Hilaire, 33607 Pessac, France
| | - Thierry Bardin
- Non-self Recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, 1 Rue Camille Saint Saëns, 33077 Bordeaux CEDEX, France
| | - Mélanie Berbon
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, 1 Rue Camille Saint Saëns, 33077 Bordeaux CEDEX, France
| | - Brice Kauffmann
- IECB, UMS 3033, US 001, CNRS, Université de Bordeaux, 2 Rue Robert Escarpit, 33607 Pessac, France
| | - Corinne Blancard
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, 1 Rue Camille Saint Saëns, 33077 Bordeaux CEDEX, France
| | - Bénédicte Salin
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, 1 Rue Camille Saint Saëns, 33077 Bordeaux CEDEX, France
| | - Antoine Loquet
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248 CBMN, IECB, CNRS, Université de Bordeaux, Allee Geoffroy Saint-Hilaire, 33607 Pessac, France
| | - Sven J Saupe
- Non-self Recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS, Université de Bordeaux, 1 Rue Camille Saint Saëns, 33077 Bordeaux CEDEX, France.
| |
Collapse
|
8
|
Milgroom MG, Smith ML, Drott MT, Nuss DL. Balancing selection at nonself recognition loci in the chestnut blight fungus, Cryphonectria parasitica, demonstrated by trans-species polymorphisms, positive selection, and even allele frequencies. Heredity (Edinb) 2018; 121:511-523. [PMID: 29426879 DOI: 10.1038/s41437-018-0060-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 11/09/2022] Open
Abstract
Balancing selection has been inferred in diverse organisms for nonself recognition genes, including those involved in immunity, mating compatibility, and vegetative incompatibility. Although selective forces maintaining polymorphisms are known for genes involved in immunity and mating, mechanisms of balancing selection for vegetative incompatibility genes in fungi are being debated. We hypothesized that allorecognition and its consequent inhibition of virus transmission contribute to the maintenance of polymorphisms in vegetative incompatibility loci (vic) in the chestnut blight fungus, Cryphonectria parasitica. Balancing selection was demonstrated at two loci, vic2 and vic6, by trans-species polymorphisms in C. parasitica, C. radicalis, and C. japonica and signatures of positive selection in gene sequences. In addition, more than half (31 of 54) of allele frequency estimates at six vic loci in nine field populations of C. parasitica from Asia and the eastern US were not significantly different from 0.5, as expected at equilibrium for two alleles per locus under balancing selection. At three vic loci, deviations from 0.5 were predicted based on the effects of heteroallelism on virus transmission. Twenty-five of 27 allele frequency estimates were greater than or equal to 0.5 for the allele that confers significantly stronger inhibition of virus transmission at three loci with asymmetric transmission. These results are consistent with the allorecognition hypothesis that vegetative incompatibility genes are under selection because of their role in reducing infection by viruses.
Collapse
Affiliation(s)
- Michael G Milgroom
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY, 14853, USA.
| | - Myron L Smith
- Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Milton T Drott
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY, 14853, USA
| | - Donald L Nuss
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD, 20850, USA.,Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV, 26506, USA
| |
Collapse
|
9
|
Gonçalves AP, Heller J, Daskalov A, Videira A, Glass NL. Regulated Forms of Cell Death in Fungi. Front Microbiol 2017; 8:1837. [PMID: 28983298 PMCID: PMC5613156 DOI: 10.3389/fmicb.2017.01837] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 09/07/2017] [Indexed: 12/15/2022] Open
Abstract
Cell death occurs in all domains of life. While some cells die in an uncontrolled way due to exposure to external cues, other cells die in a regulated manner as part of a genetically encoded developmental program. Like other eukaryotic species, fungi undergo programmed cell death (PCD) in response to various triggers. For example, exposure to external stress conditions can activate PCD pathways in fungi. Calcium redistribution between the extracellular space, the cytoplasm and intracellular storage organelles appears to be pivotal for this kind of cell death. PCD is also part of the fungal life cycle, in which it occurs during sexual and asexual reproduction, aging, and as part of development associated with infection in phytopathogenic fungi. Additionally, a fungal non-self-recognition mechanism termed heterokaryon incompatibility (HI) also involves PCD. Some of the molecular players mediating PCD during HI show remarkable similarities to major constituents involved in innate immunity in metazoans and plants. In this review we discuss recent research on fungal PCD mechanisms in comparison to more characterized mechanisms in metazoans. We highlight the role of PCD in fungi in response to exogenic compounds, fungal development and non-self-recognition processes and discuss identified intracellular signaling pathways and molecules that regulate fungal PCD.
Collapse
Affiliation(s)
- A Pedro Gonçalves
- Plant and Microbial Biology Department, University of California, BerkeleyBerkeley, CA, United States
| | - Jens Heller
- Plant and Microbial Biology Department, University of California, BerkeleyBerkeley, CA, United States
| | - Asen Daskalov
- Plant and Microbial Biology Department, University of California, BerkeleyBerkeley, CA, United States
| | - Arnaldo Videira
- Instituto de Ciências Biomédicas de Abel Salazar, Universidade do PortoPorto, Portugal.,I3S - Instituto de Investigação e Inovação em SaúdePorto, Portugal
| | - N Louise Glass
- Plant and Microbial Biology Department, University of California, BerkeleyBerkeley, CA, United States
| |
Collapse
|
10
|
A novel gene, cilia flagella associated protein 44, encoding an enzyme cleaving FtsZ and tubulin contributes to the regulation of secretory pathway. Biochem Biophys Res Commun 2017; 493:399-408. [PMID: 28887034 DOI: 10.1016/j.bbrc.2017.09.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 09/04/2017] [Indexed: 11/24/2022]
Abstract
We identified a novel gene, encoding the central region of the cilia and flagella associated protein 44 (Cfap44), that regulates trafficking of cellular components and morphology via the cleavage of cellular proteins (particularly β-tubulin). Although Cfap44 is registered in GenBank, the functions of both the central part and full-length protein are unknown except for a polymorphism associated with proprotein convertase 9 activity, the third gene of familiar hyper-cholesterolemia. In mice and humans, both unspliced and spliced RNAs were transcribed, and the spliced form was predominantly transcribed in the brain and embryonic tissues. In transfectants carrying this gene, various cellular processes such as cell division, transport of cellular components, and proteolytic processing of several proteins were found to be affected. The cleavage of β-tubulin was observed. A bacterial tubulin homolog, cell division protein FtsZ, was also cleaved in vivo and in vitro by the spliced form of Cfap44 product. Furthermore, the unspliced form showed proteolytic activity with low substrate specificity. Various biological activities of Cfap44 may be due to a direct effect of cleavage of β-tubulin inhibiting microtubule formation, or an indirect effect with the cross-recognition of the cleavage site between β-tubulin and other molecules.
Collapse
|
11
|
Abstract
ABSTRACT
For the majority of fungal species, the somatic body of an individual is a network of interconnected cells sharing a common cytoplasm and organelles. This syncytial organization contributes to an efficient distribution of resources, energy, and biochemical signals. Cell fusion is a fundamental process for fungal development, colony establishment, and habitat exploitation and can occur between hyphal cells of an individual colony or between colonies of genetically distinct individuals. One outcome of cell fusion is the establishment of a stable heterokaryon, culminating in benefits for each individual via shared resources or being of critical importance for the sexual or parasexual cycle of many fungal species. However, a second outcome of cell fusion between genetically distinct strains is formation of unstable heterokaryons and the induction of a programmed cell death reaction in the heterokaryotic cells. This reaction of nonself rejection, which is termed heterokaryon (or vegetative) incompatibility, is widespread in the fungal kingdom and acts as a defense mechanism against genome exploitation and mycoparasitism. Here, we review the currently identified molecular players involved in the process of somatic cell fusion and its regulation in filamentous fungi. Thereafter, we summarize the knowledge of the molecular determinants and mechanism of heterokaryon incompatibility and place this phenomenon in the broader context of biotropic interactions and immunity.
Collapse
|
12
|
Vegetative incompatibility in fungi: From recognition to cell death, whatever does the trick. FUNGAL BIOL REV 2016. [DOI: 10.1016/j.fbr.2016.08.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
13
|
Abstract
Repeats are ubiquitous elements of proteins and they play important roles for cellular function and during evolution. Repeats are, however, also notoriously difficult to capture computationally and large scale studies so far had difficulties in linking genetic causes, structural properties and evolutionary trajectories of protein repeats. Here we apply recently developed methods for repeat detection and analysis to a large dataset comprising over hundred metazoan genomes. We find that repeats in larger protein families experience generally very few insertions or deletions (indels) of repeat units but there is also a significant fraction of noteworthy volatile outliers with very high indel rates. Analysis of structural data indicates that repeats with an open structure and independently folding units are more volatile and more likely to be intrinsically disordered. Such disordered repeats are also significantly enriched in sites with a high functional potential such as linear motifs. Furthermore, the most volatile repeats have a high sequence similarity between their units. Since many volatile repeats also show signs of recombination, we conclude they are often shaped by concerted evolution. Intriguingly, many of these conserved yet volatile repeats are involved in host-pathogen interactions where they might foster fast but subtle adaptation in biological arms races. KEY WORDS: protein evolution, domain rearrangements, protein repeats, concerted evolution.
Collapse
Affiliation(s)
- Andreas Schüler
- Institute for Evolution and Biodiversity, Westfalian Wilhelms University, Huefferstrasse 1, Muenster, Germany
| | - Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, Westfalian Wilhelms University, Huefferstrasse 1, Muenster, Germany
| |
Collapse
|
14
|
Distribution patterns and impact of transposable elements in genes of green algae. Gene 2016; 594:151-159. [PMID: 27614292 DOI: 10.1016/j.gene.2016.09.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 09/01/2016] [Accepted: 09/06/2016] [Indexed: 11/23/2022]
Abstract
Transposable elements (TEs) are DNA sequences able to transpose in the host genome, a remarkable feature that enables them to influence evolutive trajectories of species. An investigation about the TE distribution and TE impact in different gene regions of the green algae species Chlamydomonas reinhardtii and Volvox carteri was performed. Our results indicate that TEs are very scarce near introns boundaries, suggesting that insertions in this region are negatively selected. This contrasts with previous results showing enrichment of tandem repeats in introns boundaries and suggests that different evolutionary forces are acting in these different classes of repeats. Despite the relatively low abundance of TEs in the genome of green algae when compared to mammals, the proportion of poly(A) sites derived from TEs found in C. reinhardtii was similar to that described in human and mice. This fact, associated with the enrichment of TEs in gene 5' and 3' flanks of C. reinhardtii, opens up the possibility that TEs may have considerably contributed for gene regulatory sequences evolution in this species. Moreover, it was possible identify several instances of TE exonization for C. reinhardtii, with a particularly interesting case from a gene coding for Condensin II, a protein involved in the maintenance of chromosomal structure, where the addition of a transposomal PHD finger may contribute to binding specificity of this protein. Taken together, our results suggest that the low abundance of TEs in green algae genomes is correlated with a strict negative selection process, combined with the retention of copies that contribute positively with gene structures.
Collapse
|
15
|
Lamacchia M, Dyrka W, Breton A, Saupe SJ, Paoletti M. Overlapping Podospora anserina Transcriptional Responses to Bacterial and Fungal Non Self Indicate a Multilayered Innate Immune Response. Front Microbiol 2016; 7:471. [PMID: 27148175 PMCID: PMC4835503 DOI: 10.3389/fmicb.2016.00471] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/21/2016] [Indexed: 11/13/2022] Open
Abstract
Recognition and response to non self is essential to development and survival of all organisms. It can occur between individuals of the same species or between different organisms. Fungi are established models for conspecific non self recognition in the form of vegetative incompatibility (VI), a genetically controlled process initiating a programmed cell death (PCD) leading to the rejection of a fusion cell between genetically different isolates of the same species. In Podospora anserina VI is controlled by members of the hnwd gene family encoding for proteins analogous to NOD Like Receptors (NLR) immune receptors in eukaryotes. It was hypothesized that the hnwd controlled VI reaction was derived from the fungal innate immune response. Here we analyze the P. anserina transcriptional responses to two bacterial species, Serratia fonticola to which P. anserina survives and S. marcescens to which P. anserina succumbs, and compare these to the transcriptional response induced under VI conditions. Transcriptional responses to both bacteria largely overlap, however the number of genes regulated and magnitude of regulation is more important when P. anserina survives. Transcriptional responses to bacteria also overlap with the VI reaction for both up or down regulated gene sets. Genes up regulated tend to be clustered in the genome, and display limited phylogenetic distribution. In all three responses we observed genes related to autophagy to be up-regulated. Autophagy contributes to the fungal survival in all three conditions. Genes encoding for secondary metabolites and histidine kinase signaling are also up regulated in all three conditions. Transcriptional responses also display differences. Genes involved in response to oxidative stress, or encoding small secreted proteins are essentially expressed in response to bacteria, while genes encoding NLR proteins are expressed during VI. Most functions encoded in response to bacteria favor survival of the fungus while most functions up regulated during VI would lead to cell death. These differences are discussed in the frame of a multilayered response to non self in fungi.
Collapse
Affiliation(s)
- Marina Lamacchia
- Institut de Biologie et Génétique Cellulaire, UMR 5095, Centre National de la Recherche Scientifique et Université de Bordeaux Bordeaux, France
| | - Witold Dyrka
- Equipe MAGNOME, INRIA, Université de Bordeaux, Centre National de la Recherche ScientifiqueTalence, France; Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of TechnologyWroclaw, Poland
| | - Annick Breton
- Institut de Biologie et Génétique Cellulaire, UMR 5095, Centre National de la Recherche Scientifique et Université de Bordeaux Bordeaux, France
| | - Sven J Saupe
- Institut de Biologie et Génétique Cellulaire, UMR 5095, Centre National de la Recherche Scientifique et Université de Bordeaux Bordeaux, France
| | - Mathieu Paoletti
- Institut de Biologie et Génétique Cellulaire, UMR 5095, Centre National de la Recherche Scientifique et Université de Bordeaux Bordeaux, France
| |
Collapse
|
16
|
Heller J, Zhao J, Rosenfield G, Kowbel DJ, Gladieux P, Glass NL. Characterization of Greenbeard Genes Involved in Long-Distance Kind Discrimination in a Microbial Eukaryote. PLoS Biol 2016; 14:e1002431. [PMID: 27077707 PMCID: PMC4831770 DOI: 10.1371/journal.pbio.1002431] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/11/2016] [Indexed: 01/09/2023] Open
Abstract
Microorganisms are capable of communication and cooperation to perform social activities. Cooperation can be enforced using kind discrimination mechanisms in which individuals preferentially help or punish others, depending on genetic relatedness only at certain loci. In the filamentous fungus Neurospora crassa, genetically identical asexual spores (germlings) communicate and fuse in a highly regulated process, which is associated with fitness benefits during colony establishment. Recognition and chemotropic interactions between isogenic germlings requires oscillation of the mitogen-activated protein kinase (MAPK) signal transduction protein complex (NRC-1, MEK-2, MAK-2, and the scaffold protein HAM-5) to specialized cell fusion structures termed conidial anastomosis tubes. Using a population of 110 wild N. crassa isolates, we investigated germling fusion between genetically unrelated individuals and discovered that chemotropic interactions are regulated by kind discrimination. Distinct communication groups were identified, in which germlings within one communication group interacted at high frequency, while germlings from different communication groups avoided each other. Bulk segregant analysis followed by whole genome resequencing identified three linked genes (doc-1, doc-2, and doc-3), which were associated with communication group phenotype. Alleles at doc-1, doc-2, and doc-3 fell into five haplotypes that showed transspecies polymorphism. Swapping doc-1 and doc-2 alleles from different communication group strains was necessary and sufficient to confer communication group affiliation. During chemotropic interactions, DOC-1 oscillated with MAK-2 to the tips of conidial anastomosis tubes, while DOC-2 was statically localized to the plasma membrane. Our data indicate that doc-1, doc-2, and doc-3 function as "greenbeard" genes, involved in mediating long-distance kind recognition that involves actively searching for one's own type, resulting in cooperation between non-genealogical relatives. Our findings serve as a basis for investigations into the mechanisms associated with attraction, fusion, and kind recognition in other eukaryotic species.
Collapse
Affiliation(s)
- Jens Heller
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | - Jiuhai Zhao
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | - Gabriel Rosenfield
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | - David J. Kowbel
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | | | - N. Louise Glass
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
- * E-mail:
| |
Collapse
|
17
|
Zhao J, Gladieux P, Hutchison E, Bueche J, Hall C, Perraudeau F, Glass NL. Identification of Allorecognition Loci in Neurospora crassa by Genomics and Evolutionary Approaches. Mol Biol Evol 2015; 32:2417-32. [PMID: 26025978 PMCID: PMC4540973 DOI: 10.1093/molbev/msv125] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Understanding the genetic and molecular bases of the ability to distinguish self from nonself (allorecognition) and mechanisms underlying evolution of allorecognition systems is an important endeavor for understanding cases where it becomes dysfunctional, such as in autoimmune disorders. In filamentous fungi, allorecognition can result in vegetative or heterokaryon incompatibility, which is a type of programmed cell death that occurs following fusion of genetically different cells. Allorecognition is genetically controlled by het loci, with coexpression of any combination of incompatible alleles triggering vegetative incompatibility. Herein, we identified, characterized, and inferred the evolutionary history of candidate het loci in the filamentous fungus Neurospora crassa. As characterized het loci encode proteins carrying an HET domain, we annotated HET domain genes in 25 isolates from a natural population along with the N. crassa reference genome using resequencing data. Because allorecognition systems can be affected by frequency-dependent selection favoring rare alleles (i.e., balancing selection), we mined resequencing data for HET domain loci whose alleles displayed elevated levels of variability, excess of intermediate frequency alleles, and deep gene genealogies. From these analyses, 34 HET domain loci were identified as likely to be under balancing selection. Using transformation, incompatibility assays and genetic analyses, we determined that one of these candidates functioned as a het locus (het-e). The het-e locus has three divergent allelic groups that showed signatures of positive selection, intra- and intergroup recombination, and trans-species polymorphism. Our findings represent a compelling case of balancing selection functioning on multiple alleles across multiple loci potentially involved in allorecognition.
Collapse
Affiliation(s)
- Jiuhai Zhao
- Plant and Microbial Biology Department, University of California, Berkeley
| | - Pierre Gladieux
- Plant and Microbial Biology Department, University of California, Berkeley INRA, UMR BGPI, TA A54/K, Montpellier, France; CIRAD, Montpellier, France
| | - Elizabeth Hutchison
- Plant and Microbial Biology Department, University of California, Berkeley Biology Department, 1 College Circle SUNY Geneseo, Geneseo, NY
| | - Joanna Bueche
- Plant and Microbial Biology Department, University of California, Berkeley
| | - Charles Hall
- Plant and Microbial Biology Department, University of California, Berkeley
| | - Fanny Perraudeau
- Plant and Microbial Biology Department, University of California, Berkeley Ecole Polytechnique, Palaiseau, France
| | - N Louise Glass
- Plant and Microbial Biology Department, University of California, Berkeley
| |
Collapse
|
18
|
Schaper E, Anisimova M. The evolution and function of protein tandem repeats in plants. THE NEW PHYTOLOGIST 2015; 206:397-410. [PMID: 25420631 DOI: 10.1111/nph.13184] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 10/18/2014] [Indexed: 05/27/2023]
Abstract
Sequence tandem repeats (TRs) are abundant in proteomes across all domains of life. For plants, little is known about their distribution or contribution to protein function. We exhaustively annotated TRs and studied the evolution of TR unit variations for all Ensembl plants. Using phylogenetic patterns of TR units, we detected conserved TRs with unit number and order preserved during evolution, and those TRs that have diverged via recent TR unit gains/losses. We correlated the mode of evolution of TRs to protein function. TR number was strongly correlated with proteome size, with about one-half of all TRs recognized as common protein domains. The majority of TRs have been highly conserved over long evolutionary distances, some since the separation of red algae and green plants c. 1.6 billion yr ago. Conversely, recurrent recent TR unit mutations were rare. Our results suggest that the first TRs by far predate the first plants, and that TR appearance is an ongoing process with similar rates across the plant kingdom. Interestingly, the few detected highly mutable TRs might provide a source of variation for rapid adaptation. In particular, such TRs are enriched in leucine-rich repeats (LRRs) commonly found in R genes, where TR unit gain/loss may facilitate resistance to emerging pathogens.
Collapse
Affiliation(s)
- Elke Schaper
- Department of Computer Science, ETH Zürich, Zürich, 8092, Switzerland
- Institute of Integrative Biology, ETH Zürich, Zürich, 8092, Switzerland
- Vital-IT Competency Center, Swiss Institute for Bioinformatics (SIB), Lausanne, 1015, Switzerland
| | - Maria Anisimova
- Institute of Applied Simulation (IAS), School of Life Sciences and Facility Management, Zürich University of Applied Sciences (ZHAW), Wädenswil, 8820, Switzerland
| |
Collapse
|
19
|
Daskalov A, Habenstein B, Martinez D, Debets AJM, Sabaté R, Loquet A, Saupe SJ. Signal transduction by a fungal NOD-like receptor based on propagation of a prion amyloid fold. PLoS Biol 2015; 13:e1002059. [PMID: 25671553 PMCID: PMC4344463 DOI: 10.1371/journal.pbio.1002059] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 12/29/2014] [Indexed: 01/09/2023] Open
Abstract
In the fungus Podospora anserina, the [Het-s] prion induces programmed cell death by activating the HET-S pore-forming protein. The HET-s β-solenoid prion fold serves as a template for converting the HET-S prion-forming domain into the same fold. This conversion, in turn, activates the HET-S pore-forming domain. The gene immediately adjacent to het-S encodes NWD2, a Nod-like receptor (NLR) with an N-terminal motif similar to the elementary repeat unit of the β-solenoid fold. NLRs are immune receptors controlling cell death and host defense processes in animals, plants and fungi. We have proposed that, analogously to [Het-s], NWD2 can activate the HET-S pore-forming protein by converting its prion-forming region into the β-solenoid fold. Here, we analyze the ability of NWD2 to induce formation of the β-solenoid prion fold. We show that artificial NWD2 variants induce formation of the [Het-s] prion, specifically in presence of their cognate ligands. The N-terminal motif is responsible for this prion induction, and mutations predicted to affect the β-solenoid fold abolish templating activity. In vitro, the N-terminal motif assembles into infectious prion amyloids that display a structure resembling the β-solenoid fold. In vivo, the assembled form of the NWD2 N-terminal region activates the HET-S pore-forming protein. This study documenting the role of the β-solenoid fold in fungal NLR function further highlights the general importance of amyloid and prion-like signaling in immunity-related cell fate pathways. The fungus Podospora anserina uses a prion amyloid fold as a signal transduction device between a Nod-like receptor and a downstream cell death execution protein. Although amyloids are best known as protein aggregates that are responsible for fatal neurodegenerative diseases, amyloid structures can also fulfill functional roles in cells. In particular, the controlled formation of amyloid structures appears to be involved in different signaling processes in the context of programmed cell death and host defense. The [Het-s] prion of the filamentous fungus Podospora anserina is a model system in which the 3-D structure of the prion form has been solved. The [Het-s] prion works as an activation switch for a second protein termed HET-S. HET-S is a pore-forming protein that is activated when the [Het-s] prion causes its C-terminal domain to adopt an amyloid-like fold. The protein encoded by the gene adjacent to het-S is a Nod-like receptor (NLR) called NWD2. NLRs are immune receptors that control host defense and cell death processes in plants, animals, and fungi. We show that NWD2 can template the formation of the [Het-s] prion fold in a ligand-controlled manner. NWD2 has an N-terminal motif homologous to the HET-S/s prion-forming region; we find that this region is both necessary and sufficient for its prion-inducing activity, and our functional and structural approaches reveal that the N-terminal region of NWD2 adopts a fold closely related to that of the HET-S/s prion. This study illustrates how the controlled formation of a prion amyloid fold can be used in a signaling process whereby a Nod-like receptor protein activates a downstream cell death execution domain.
Collapse
Affiliation(s)
- Asen Daskalov
- Non-self recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS—Université de Bordeaux, Bordeaux, France
| | - Birgit Habenstein
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS, CBMN, UMR 5248, Pessac, France
| | - Denis Martinez
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS, CBMN, UMR 5248, Pessac, France
| | - Alfons J. M. Debets
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg, Wageningen, The Netherlands
| | - Raimon Sabaté
- Institut de Nanociència i nanotecnologia, Departament Fisicoquímica, Universitat de Barcelona, Joan XXIII s/n, Barcelona, Spain
| | - Antoine Loquet
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS, CBMN, UMR 5248, Pessac, France
| | - Sven J. Saupe
- Non-self recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS—Université de Bordeaux, Bordeaux, France
- * E-mail:
| |
Collapse
|
20
|
Dyrka W, Lamacchia M, Durrens P, Kobe B, Daskalov A, Paoletti M, Sherman DJ, Saupe SJ. Diversity and variability of NOD-like receptors in fungi. Genome Biol Evol 2014; 6:3137-58. [PMID: 25398782 PMCID: PMC4986451 DOI: 10.1093/gbe/evu251] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are intracellular receptors that control innate immunity and other biotic interactions in animals and plants. NLRs have been characterized in plant and animal lineages, but in fungi, this gene family has not been systematically described. There is however previous indications of the involvement of NLR-like genes in nonself recognition and programmed cell death in fungi. We have analyzed 198 fungal genomes for the presence of NLRs and have annotated a total of 5,616 NLR candidates. We describe their phylogenetic distribution, domain organization, and evolution. Fungal NLRs are characterized by a great diversity of domain organizations, suggesting frequently occurring combinatorial assortments of different effector, NOD and repeat domains. The repeat domains are of the WD, ANK, and TPR type; no LRR motifs were found. As previously documented for WD-repeat domains of fungal NLRs, TPR, and ANK repeats evolve under positive selection and show highly conserved repeats and repeat length polymorphism, suggesting the possibility of concerted evolution of these repeats. We identify novel effector domains not previously found associated with NLRs, whereas others are related to effector domains of plant or animals NLRs. In particular, we show that the HET domain found in fungal NLRs may be related to Toll/interleukin-1 receptor domains found in animal and plant immune receptors. This description of fungal NLR repertoires reveals both similarities and differences with plant and animals NLR collections, highlights the importance of domain reassortment and repeat evolution and provides a novel entry point to explore the evolution of NLRs in eukaryotes.
Collapse
Affiliation(s)
- Witold Dyrka
- INRIA-Université Bordeaux-CNRS, MAGNOME, Talence, France
| | - Marina Lamacchia
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| | - Pascal Durrens
- INRIA-Université Bordeaux-CNRS, MAGNOME, Talence, France
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Centre for Infectious Disease Research, University of Queensland, Brisbane, Queensland, Australia
| | - Asen Daskalov
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| | - Matthieu Paoletti
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| | | | - Sven J Saupe
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| |
Collapse
|
21
|
Schaper E, Gascuel O, Anisimova M. Deep conservation of human protein tandem repeats within the eukaryotes. Mol Biol Evol 2014; 31:1132-48. [PMID: 24497029 PMCID: PMC3995336 DOI: 10.1093/molbev/msu062] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Tandem repeats (TRs) are a major element of protein sequences in all domains of life. They are particularly abundant in mammals, where by conservative estimates one in three proteins contain a TR. High generation-scale duplication and deletion rates were reported for nucleic TR units. However, it is not known whether protein TR units can also be frequently lost or gained providing a source of variation for rapid adaptation of protein function, or alternatively, tend to have conserved TR unit configurations over long evolutionary times. To obtain a systematic picture, we performed a proteome-wide analysis of the mode of evolution for human protein TRs. For this purpose, we propose a novel method for the detection of orthologous TRs based on circular profile hidden Markov models. For all detected TRs, we reconstructed bispecies TR unit phylogenies across 61 eukaryotes ranging from human to yeast. Moreover, we performed additional analyses to correlate functional and structural annotations of human TRs with their mode of evolution. Surprisingly, we find that the vast majority of human TRs are ancient, with TR unit number and order preserved intact since distant speciation events. For example, ≥61% of all human TRs have been strongly conserved at least since the root of all mammals, approximately 300 Ma. Further, we find no human protein TR that shows evidence for strong recent duplications and deletions. The results are in contrast to the high generation-scale mutability of nucleic TRs. Presumably, most protein TRs fold into stable and conserved structures that are indispensable for the function of the TR-containing protein. All of our data and results are available for download from http://www.atgc-montpellier.fr/TRE.
Collapse
Affiliation(s)
- Elke Schaper
- Department of Computer Science, ETH Zürich, Zürich, Switzerland
| | | | | |
Collapse
|
22
|
Bastiaans E, Debets AJM, Aanen DK, van Diepeningen AD, Saupe SJ, Paoletti M. Natural variation of heterokaryon incompatibility gene het-c in Podospora anserina reveals diversifying selection. Mol Biol Evol 2014; 31:962-74. [PMID: 24448643 PMCID: PMC3969566 DOI: 10.1093/molbev/msu047] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In filamentous fungi, allorecognition takes the form of heterokaryon incompatibility, a cell death reaction triggered when genetically distinct hyphae fuse. Heterokaryon incompatibility is controlled by specific loci termed het-loci. In this article, we analyzed the natural variation in one such fungal allorecognition determinant, the het-c heterokaryon incompatibility locus of the filamentous ascomycete Podospora anserina. The het-c locus determines an allogenic incompatibility reaction together with two unlinked loci termed het-d and het-e. Each het-c allele is incompatible with a specific subset of the het-d and het-e alleles. We analyzed variability at the het-c locus in a population of 110 individuals, and in additional isolates from various localities. We identified a total of 11 het-c alleles, which define 7 distinct incompatibility specificity classes in combination with the known het-d and het-e alleles. We found that the het-c allorecognition gene of P. anserina is under diversifying selection. We find a highly unequal allele distribution of het-c in the population, which contrasts with the more balanced distribution of functional groups of het-c based on their allorecognition function. One explanation for the observed het-c diversity in the population is its function in allorecognition. However, alleles that are most efficient in allorecognition are rare. An alternative and not exclusive explanation for the observed diversity is that het-c is involved in pathogen recognition. In Arabidopsis thaliana, a homolog of het-c is a pathogen effector target, supporting this hypothesis. We hypothesize that the het-c diversity in P. anserina results from both its functions in pathogen-defense, and allorecognition.
Collapse
Affiliation(s)
- Eric Bastiaans
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg, Wageningen, The Netherlands
| | | | | | | | | | | |
Collapse
|
23
|
Van der Nest MA, Olson A, Lind M, Vélëz H, Dalman K, Brandström Durling M, Karlsson M, Stenlid J. Distribution and evolution of het gene homologs in the basidiomycota. Fungal Genet Biol 2013; 64:45-57. [PMID: 24380733 DOI: 10.1016/j.fgb.2013.12.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/04/2013] [Accepted: 12/20/2013] [Indexed: 12/24/2022]
Abstract
In filamentous fungi a system known as somatic incompatibility (SI) governs self/non-self recognition. SI is controlled by a regulatory signaling network involving proteins encoded at the het (heterokaryon incompatible) loci. Despite the wide occurrence of SI, the molecular identity and structure of only a small number of het genes and their products have been characterized in the model fungi Neurospora crassa and Podospora anserina. Our aim was to identify and study the distribution and evolution of putative het gene homologs in the Basidiomycota. For this purpose we used the information available for the model fungi to identify homologs of het genes in other fungi, especially the Basidiomycota. Putative het-c, het-c2 and un-24 homologs, as well as sequences containing the NACHT, HET or WD40 domains present in the het-e, het-r, het-6 and het-d genes were identified in certain members of the Ascomycota and Basidiomycota. The widespread phylogenetic distribution of certain het genes may reflect the fact that the encoded proteins are involved in fundamental cellular processes other than SI. Although homologs of het-S were previously known only from the Sordariomycetes (Ascomycota), we also identified a putative homolog of this gene in Gymnopus luxurians (Basidiomycota, class Agaricomycetes). Furthermore, with the exception of un-24, all of the putative het genes identified occurred mostly in a multi-copy fashion, some with lineage and species-specific expansions. Overall our results indicated that gene duplication followed by gene loss and/or gene family expansion, as well as multiple events of domain fusion and shuffling played an important role in the evolution of het gene homologs of Basidiomycota and other filamentous fungi.
Collapse
Affiliation(s)
- M A Van der Nest
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden.
| | - A Olson
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - M Lind
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - H Vélëz
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - K Dalman
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - M Brandström Durling
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - M Karlsson
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - J Stenlid
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| |
Collapse
|
24
|
Dawe AL, Nuss DL. Hypovirus molecular biology: from Koch's postulates to host self-recognition genes that restrict virus transmission. Adv Virus Res 2013; 86:109-47. [PMID: 23498905 DOI: 10.1016/b978-0-12-394315-6.00005-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The idea that viruses can be used to control fungal diseases has been a driving force in mycovirus research since the earliest days. Viruses in the family Hypoviridae associated with reduced virulence (hypovirulence) of the chestnut blight fungus, Cryphonectria parasitica, have held a prominent place in this research. This has been due in part to the severity of the chestnut blight epidemics in North America and Europe and early reports of hypovirulence-mediated mitigation of disease in European forests and successful application for control of chestnut blight in chestnut orchards. A more recent contributing factor has been the development of a hypovirus/C. parasitica experimental system that has overcome many of the challenges associated with mycovirus research, stemming primarily from the exclusive intracellular lifestyle shared by all mycoviruses. This chapter will focus on hypovirus molecular biology with an emphasis on the development of the hypovirus/C. parasitica experimental system and its contributions to fundamental and practical advances in mycovirology and the broader understanding of virus-host interactions and fungal pathogenesis.
Collapse
Affiliation(s)
- Angus L Dawe
- Department of Biology, New Mexico State University, Las Cruces, NM, USA
| | | |
Collapse
|
25
|
Bornberg-Bauer E, Albà MM. Dynamics and adaptive benefits of modular protein evolution. Curr Opin Struct Biol 2013; 23:459-66. [PMID: 23562500 DOI: 10.1016/j.sbi.2013.02.012] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 02/15/2013] [Accepted: 02/15/2013] [Indexed: 11/29/2022]
Abstract
During protein evolution, novel domain arrangements are continuously formed. Rearrangements are important for the creation of molecular biodiversity and for functional molecular changes which underlie developmental shifts in the bauplan of organisms. Here we review the mechanisms by which new arrangements arise and the potential benefits of rearrangements. We concentrate on how new domains emerge and why they rapidly spread across genomes, gaining higher copy numbers than older, more established domains. This spread is most likely a consequence of their high adaptive potential but is unlikely to make up on its own for the drastic loss of domains, which is observed across different taxa. We show that a significant portion of the recently emerged domains, especially those in multidomain families, are highly disordered and speculate about the significance of these findings for the evolvability of novel genetic material.
Collapse
Affiliation(s)
- Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, School of Biological Sciences, University of Münster, Hüfferstrasse 1, D48149 Münster, Germany.
| | | |
Collapse
|
26
|
Smith RP, Wellman K, Smith ML. Trans-species activity of a nonself recognition domain. BMC Microbiol 2013; 13:63. [PMID: 23517247 PMCID: PMC3618301 DOI: 10.1186/1471-2180-13-63] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 02/07/2013] [Indexed: 11/18/2022] Open
Abstract
Background The ability to distinguish nonself from self is a fundamental characteristic of biological systems. In the filamentous fungus Neurospora crassa, multiple incompatibility genes mediate nonself recognition during vegetative growth. One of these genes, un-24, encodes both nonself recognition function and the large subunit of a type I ribonucleotide reductase, an evolutionarily conserved enzyme that is essential for the conversion of NDP precursors into dNDPs for use in DNA synthesis. Previous studies have shown that co-expression of the two allelic forms of un-24, Oakridge (OR) and Panama (PA), in the same cell results in cell death. Results We identify a 135 amino acid nonself recognition domain in the C-terminus region of UN-24 that confers an incompatibility-like phenotype when expressed in the yeast, Saccharomyces cerevisiae. Low-level expression of this domain results in several cytological and phenotypic characteristics consistent with an incompatibility reaction in filamentous fungi. These incompatibility phenotypes are correlated with the presence of a non-reducible complex consisting of the PA incompatibility domain and Rnr1p, a large subunit of ribonucleotide reductase in yeast. When the PA incompatibility domain is switched to high-level expression, the incompatibility phenotype transitions to wild-type concomitant with the appearance of a complex containing the PA incompatibility domain and Ssa1p, an Hsp70 homolog. Conclusions Results from this study provide insights into the mechanism and control of vegetative nonself recognition mediated by ribonucleotide reductase in N. crassa, thus establishing the yeast system as a powerful tool to study fungal nonself recognition. Our work shows that heat shock proteins may function to deactivate vegetative incompatibility systems, as required for entry into the sexual cycle. Finally, our results suggest that variations on the PA incompatibility domain may serve as novel and specific antimicrobial peptides.
Collapse
|
27
|
Moore AD, Grath S, Schüler A, Huylmans AK, Bornberg-Bauer E. Quantification and functional analysis of modular protein evolution in a dense phylogenetic tree. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:898-907. [PMID: 23376183 DOI: 10.1016/j.bbapap.2013.01.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/06/2013] [Accepted: 01/09/2013] [Indexed: 12/24/2022]
Abstract
Modularity is a hallmark of molecular evolution. Whether considering gene regulation, the components of metabolic pathways or signaling cascades, the ability to reuse autonomous modules in different molecular contexts can expedite evolutionary innovation. Similarly, protein domains are the modules of proteins, and modular domain rearrangements can create diversity with seemingly few operations in turn allowing for swift changes to an organism's functional repertoire. Here, we assess the patterns and functional effects of modular rearrangements at high resolution. Using a well resolved and diverse group of pancrustaceans, we illustrate arrangement diversity within closely related organisms, estimate arrangement turnover frequency and establish, for the first time, branch-specific rate estimates for fusion, fission, domain addition and terminal loss. Our results show that roughly 16 new arrangements arise per million years and that between 64% and 81% of these can be explained by simple, single-step modular rearrangement events. We find evidence that the frequencies of fission and terminal deletion events increase over time, and that modular rearrangements impact all levels of the cellular signaling apparatus and thus may have strong adaptive potential. Novel arrangements that cannot be explained by simple modular rearrangements contain a significant amount of repeat domains that occur in complex patterns which we term "supra-repeats". Furthermore, these arrangements are significantly longer than those with a single-step rearrangement solution, suggesting that such arrangements may result from multi-step events. In summary, our analysis provides an integrated view and initial quantification of the patterns and functional impact of modular protein evolution in a well resolved phylogenetic tree. This article is part of a Special Issue entitled: The emerging dynamic view of proteins: Protein plasticity in allostery, evolution and self-assembly.
Collapse
Affiliation(s)
- Andrew D Moore
- Institute for Evolution and Biodiversity, Münster, Germany
| | | | | | | | | |
Collapse
|
28
|
|
29
|
Genomic clustering and homology between HET-S and the NWD2 STAND protein in various fungal genomes. PLoS One 2012; 7:e34854. [PMID: 22493719 PMCID: PMC3321046 DOI: 10.1371/journal.pone.0034854] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 03/08/2012] [Indexed: 12/23/2022] Open
Abstract
Background Prions are infectious proteins propagating as self-perpetuating amyloid polymers. The [Het-s] prion of Podospora anserina is involved in a cell death process associated with non-self recognition. The prion forming domain (PFD) of HET-s adopts a β-solenoid amyloid structure characterized by the two fold repetition of an elementary triangular motif. [Het-s] induces cell death when interacting with HET-S, an allelic variant of HET-s. When templated by [Het-s], HET-S undergoes a trans-conformation, relocates to the cell membrane and induces toxicity. Methodology/Principal Findings Here, comparing HET-s homologs from different species, we devise a consensus for the HET-s elementary triangular motif. We use this motif to screen genomic databases and find a match to the N-terminus of NWD2, a STAND protein, encoded by the gene immediately adjacent to het-S. STAND proteins are signal transducing ATPases which undergo ligand-induced oligomerisation. Homology modelling predicts that the NWD2 N-terminal region adopts a HET-s-like fold. We propose that upon NWD2 oligomerisation, these N-terminal extensions adopt the β-solenoid fold and template HET-S to adopt the amyloid fold and trigger toxicity. We extend this model to a putative prion, the σ infectious element in Nectria haematococca, because the s locus controlling propagation of σ also encodes a STAND protein and displays analogous features. Comparative genomic analyses indicate evolutionary conservation of these STAND/prion-like gene pairs, identify a number of novel prion candidates and define, in addition to the HET-s PFD motif, two distinct, novel putative PFD-like motifs. Conclusions/Significance We suggest the existence, in the fungal kingdom, of a widespread and evolutionarily conserved mode of signal transduction based on the transmission of an amyloid-fold from a NOD-like STAND receptor protein to an effector protein.
Collapse
|
30
|
Kersting AR, Bornberg-Bauer E, Moore AD, Grath S. Dynamics and adaptive benefits of protein domain emergence and arrangements during plant genome evolution. Genome Biol Evol 2012; 4:316-29. [PMID: 22250127 PMCID: PMC3318442 DOI: 10.1093/gbe/evs004] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Plant genomes are generally very large, mostly paleopolyploid, and have numerous gene duplicates and complex genomic features such as repeats and transposable elements. Many of these features have been hypothesized to enable plants, which cannot easily escape environmental challenges, to rapidly adapt. Another mechanism, which has recently been well described as a major facilitator of rapid adaptation in bacteria, animals, and fungi but not yet for plants, is modular rearrangement of protein-coding genes. Due to the high precision of profile-based methods, rearrangements can be well captured at the protein level by characterizing the emergence, loss, and rearrangements of protein domains, their structural, functional, and evolutionary building blocks. Here, we study the dynamics of domain rearrangements and explore their adaptive benefit in 27 plant and 3 algal genomes. We use a phylogenomic approach by which we can explain the formation of 88% of all arrangements by single-step events, such as fusion, fission, and terminal loss of domains. We find many domains are lost along every lineage, but at least 500 domains are novel, that is, they are unique to green plants and emerged more or less recently. These novel domains duplicate and rearrange more readily within their genomes than ancient domains and are overproportionally involved in stress response and developmental innovations. Novel domains more often affect regulatory proteins and show a higher degree of structural disorder than ancient domains. Whereas a relatively large and well-conserved core set of single-domain proteins exists, long multi-domain arrangements tend to be species-specific. We find that duplicated genes are more often involved in rearrangements. Although fission events typically impact metabolic proteins, fusion events often create new signaling proteins essential for environmental sensing. Taken together, the high volatility of single domains and complex arrangements in plant genomes demonstrate the importance of modularity for environmental adaptability of plants.
Collapse
Affiliation(s)
- Anna R Kersting
- Evolutionary Bioinformatics Group, Institute for Evolution and Biodiversity, University of Muenster (WWU), Germany
| | | | | | | |
Collapse
|
31
|
Lafontaine DL, Smith ML. Diverse interactions mediate asymmetric incompatibility by the het-6 supergene complex in Neurospora crassa. Fungal Genet Biol 2011; 49:65-73. [PMID: 22094057 DOI: 10.1016/j.fgb.2011.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 10/20/2011] [Accepted: 11/02/2011] [Indexed: 11/28/2022]
Abstract
Heterokaryon incompatibility (HI) in filamentous fungi is a form of nonself recognition that operates during the vegetative phase of the life cycle. One HI gene complex in Neurospora crassa, the het-6 locus, comprises two incompatibility genes, het-6 and un-24, each having two allelic variants, Oak Ridge (OR) and Panama (PA). The un-24 gene also encodes the large subunit of ribonucleotide reductase while het-6 appears to be a member of a repetitive gene family with no other known function aside from HI. These two genes are in severe linkage disequilibrium such that only un-24(OR)het-6(OR) and un-24(PA)het-6(PA) haplotypes occur in nature. In this study we unravel several genetic interactions that govern the HI functions of this gene complex. We use novel un-24(PA)het-6(OR) strains and het-6 deletion strains to demonstrate that nonallelic interactions occur between un-24 and het-6 and reveal an allelic incompatibility interaction between the OR and PA forms of un-24 that is asymmetrically enhanced by the presence of het-6(OR) or het-6(PA). We also show how two allelic forms of vib-1, a suppressor of het-c- and mat-associated incompatibility, differentially act as recessive suppressors of HI associated with nonallelic interactions between un-24(PA) and het-6(OR). In contrast, vib-1 is a dominant suppressor of HI associated with allelic differences at un-24 and a dominant partial suppressor of the un-24(OR) and het-6(PA) nonallelic interaction. The range of suppressor activities is largely explained by an interesting differential effect on het-6(OR) and het-6(PA) transcript levels by VIB-1.
Collapse
|
32
|
Molecular characterization of vegetative incompatibility genes that restrict hypovirus transmission in the chestnut blight fungus Cryphonectria parasitica. Genetics 2011; 190:113-27. [PMID: 22021387 PMCID: PMC3249360 DOI: 10.1534/genetics.111.133983] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genetic nonself recognition systems such as vegetative incompatibility operate in many filamentous fungi to regulate hyphal fusion between genetically dissimilar individuals and to restrict the spread of virulence-attenuating mycoviruses that have potential for biological control of pathogenic fungi. We report here the use of a comparative genomics approach to identify seven candidate polymorphic genes associated with four vegetative incompatibility (vic) loci of the chestnut blight fungus Cryphonectria parasitica. Disruption of candidate alleles in one of two strains that were heteroallelic at vic2, vic6, or vic7 resulted in enhanced virus transmission, but did not prevent barrage formation associated with mycelial incompatibility. Detailed characterization of the vic6 locus revealed the involvement of nonallelic interactions between two tightly linked genes in barrage formation, heterokaryon formation, and asymmetric, gene-specific influences on virus transmission. The combined results establish molecular identities of genes associated with four C. parasitica vic loci and provide insights into how these recognition factors interact to trigger incompatibility and restrict virus transmission.
Collapse
|
33
|
van der Nest MA, Steenkamp ET, Slippers B, Mongae A, van Zyl K, Stenlid J, Wingfield MJ, Wingfield BD. Gene expression associated with vegetative incompatibility in Amylostereum areolatum. Fungal Genet Biol 2011; 48:1034-43. [PMID: 21889597 DOI: 10.1016/j.fgb.2011.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 08/11/2011] [Accepted: 08/15/2011] [Indexed: 12/23/2022]
Abstract
In filamentous fungi, vegetative compatibility among individuals of the same species is determined by the genes encoded at the heterokaryon incompatibility (het) loci. The hyphae of genetically similar individuals that share the same allelic specificities at their het loci are able to fuse and intermingle, while different allelic specificities at the het loci result in cell death of the interacting hyphae. In this study, suppression subtractive hybridization (SSH) followed by pyrosequencing and quantitative reverse transcription PCR were used to identify genes that are selectively expressed when vegetatively incompatible individuals of Amylostereum areolatum interact. The SSH library contained genes associated with various cellular processes, including cell-cell adhesion, stress and defence responses, as well as cell death. Some of the transcripts encoded proteins that were previously implicated in the stress and defence responses associated with vegetative incompatibility. Other transcripts encoded proteins known to be associated with programmed cell death, but have not previously been linked with vegetative incompatibility. Results of this study have considerably increased our knowledge of the processes underlying vegetative incompatibility in Basidiomycetes in general and A. areolatum in particular.
Collapse
Affiliation(s)
- M A van der Nest
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Hall C, Welch J, Kowbel DJ, Glass NL. Evolution and diversity of a fungal self/nonself recognition locus. PLoS One 2010; 5:e14055. [PMID: 21124910 PMCID: PMC2988816 DOI: 10.1371/journal.pone.0014055] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 10/25/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Self/nonself discrimination is an essential feature for pathogen recognition and graft rejection and is a ubiquitous phenomenon in many organisms. Filamentous fungi, such as Neurospora crassa, provide a model for analyses of population genetics/evolution of self/nonself recognition loci due to their haploid nature, small genomes and excellent genetic/genomic resources. In N. crassa, nonself discrimination during vegetative growth is determined by 11 heterokaryon incompatibility (het) loci. Cell fusion between strains that differ in allelic specificity at any of these het loci triggers a rapid programmed cell death response. METHODOLOGY/PRINCIPAL FINDINGS In this study, we evaluated the evolution, population genetics and selective mechanisms operating at a nonself recognition complex consisting of two closely linked loci, het-c (NCU03493) and pin-c (NCU03494). The genomic position of pin-c next to het-c is unique to Neurospora/Sordaria species, and originated by gene duplication after divergence from other species within the Sordariaceae. The het-c pin-c alleles in N. crassa are in severe linkage disequilibrium and consist of three haplotypes, het-c1/pin-c1, het-c2/pin-c2 and het-c3/pin-c3, which are equally frequent in population samples and exhibit trans-species polymorphisms. The absence of recombinant haplotypes is correlated with divergence of the het-c/pin-c intergenic sequence. Tests for positive and balancing selection at het-c and pin-c support the conclusion that both of these loci are under non-neutral balancing selection; other regions of both genes appear to be under positive selection. Our data show that the het-c2/pin-c2 haplotype emerged by a recombination event between the het-c1/pin-c1 and het-c3/pin-c3 approximately 3-12 million years ago. CONCLUSIONS/SIGNIFICANCE These results support models by which loci that confer nonself discrimination form by the association of polymorphic genes with genes containing HET domains. Distinct allele classes can emerge by recombination and positive selection and are subsequently maintained by balancing selection and divergence of intergenic sequence resulting in recombination blocks between haplotypes.
Collapse
Affiliation(s)
- Charles Hall
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
| | - Juliet Welch
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
| | - David J. Kowbel
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
| | - N. Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
- * E-mail:
| |
Collapse
|
35
|
Reshef D, Itzhaki Z, Schueler-Furman O. Increased sequence conservation of domain repeats in prokaryotic proteins. Trends Genet 2010; 26:383-7. [DOI: 10.1016/j.tig.2010.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 06/11/2010] [Accepted: 06/11/2010] [Indexed: 10/19/2022]
|