1
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Lihanova Y, Nagel R, Jakob T, Sasso S. Characterization of activating cis-regulatory elements from the histone genes of Chlamydomonas reinhardtii. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 119:525-539. [PMID: 38693717 DOI: 10.1111/tpj.16781] [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: 06/27/2023] [Revised: 04/08/2024] [Accepted: 04/12/2024] [Indexed: 05/03/2024]
Abstract
Regulation of gene expression in eukaryotes is controlled by cis-regulatory modules (CRMs). A major class of CRMs are enhancers which are composed of activating cis-regulatory elements (CREs) responsible for upregulating transcription. To date, most enhancers and activating CREs have been studied in angiosperms; in contrast, our knowledge about these key regulators of gene expression in green algae is limited. In this study, we aimed at characterizing putative activating CREs/CRMs from the histone genes of the unicellular model alga Chlamydomonas reinhardtii. To test the activity of four candidates, reporter constructs consisting of a tetramerized CRE, an established promoter, and a gene for the mCerulean3 fluorescent protein were incorporated into the nuclear genome of C. reinhardtii, and their activity was quantified by flow cytometry. Two tested candidates, Eupstr and Ehist cons, significantly upregulated gene expression and were characterized in detail. Eupstr, which originates from highly expressed genes of C. reinhardtii, is an orientation-independent CRE capable of activating both the RBCS2 and β2-tubulin promoters. Ehist cons, which is a CRM from histone genes of angiosperms, upregulates the β2-tubulin promoter in C. reinhardtii over a distance of at least 1.5 kb. The octamer motif present in Ehist cons was identified in C. reinhardtii and the related green algae Chlamydomonas incerta, Chlamydomonas schloesseri, and Edaphochlamys debaryana, demonstrating its high evolutionary conservation. The results of this investigation expand our knowledge about the regulation of gene expression in green algae. Furthermore, the characterized activating CREs/CRMs can be applied as valuable genetic tools.
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Affiliation(s)
- Yuliia Lihanova
- Department of Plant Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Raimund Nagel
- Department of Plant Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Torsten Jakob
- Department of Plant Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Severin Sasso
- Department of Plant Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
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2
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Gao J, Li F. Heterochromatin repeat organization at an individual level: Rex1BD and the 14-3-3 protein coordinate to shape the epigenetic landscape within heterochromatin repeats. Bioessays 2024; 46:e2400030. [PMID: 38679759 DOI: 10.1002/bies.202400030] [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: 02/01/2024] [Revised: 04/09/2024] [Accepted: 04/15/2024] [Indexed: 05/01/2024]
Abstract
In eukaryotic cells, heterochromatin is typically composed of tandem DNA repeats and plays crucial roles in gene expression and genome stability. It has been reported that silencing at individual units within tandem heterochromatin repeats exhibits a position-dependent variation. However, how the heterochromatin is organized at an individual repeat level remains poorly understood. Using a novel genetic approach, our recent study identified a conserved protein Rex1BD required for position-dependent silencing within heterochromatin repeats. We further revealed that Rex1BD interacts with the 14-3-3 protein to regulate heterochromatin silencing by linking RNAi and HDAC pathways. In this review, we discuss how Rex1BD and the 14-3-3 protein coordinate to modulate heterochromatin organization at the individual repeat level, and comment on the biological significance of the position-dependent effect in heterochromatin repeats. We also identify the knowledge gaps that still need to be unveiled in the field.
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Affiliation(s)
- Jinxin Gao
- Department of Biology, New York University, New York, New York, USA
| | - Fei Li
- Department of Biology, New York University, New York, New York, USA
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3
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Wang B, Jia Y, Dang N, Yu J, Bush SJ, Gao S, He W, Wang S, Guo H, Yang X, Ma W, Ye K. Near telomere-to-telomere genome assemblies of two Chlorella species unveil the composition and evolution of centromeres in green algae. BMC Genomics 2024; 25:356. [PMID: 38600443 PMCID: PMC11005252 DOI: 10.1186/s12864-024-10280-8] [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: 02/28/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024] Open
Abstract
BACKGROUND Centromeres play a crucial and conserved role in cell division, although their composition and evolutionary history in green algae, the evolutionary ancestors of land plants, remains largely unknown. RESULTS We constructed near telomere-to-telomere (T2T) assemblies for two Trebouxiophyceae species, Chlorella sorokiniana NS4-2 and Chlorella pyrenoidosa DBH, with chromosome numbers of 12 and 13, and genome sizes of 58.11 Mb and 53.41 Mb, respectively. We identified and validated their centromere sequences using CENH3 ChIP-seq and found that, similar to humans and higher plants, the centromeric CENH3 signals of green algae display a pattern of hypomethylation. Interestingly, the centromeres of both species largely comprised transposable elements, although they differed significantly in their composition. Species within the Chlorella genus display a more diverse centromere composition, with major constituents including members of the LTR/Copia, LINE/L1, and LINE/RTEX families. This is in contrast to green algae including Chlamydomonas reinhardtii, Coccomyxa subellipsoidea, and Chromochloris zofingiensis, in which centromere composition instead has a pronounced single-element composition. Moreover, we observed significant differences in the composition and structure of centromeres among chromosomes with strong collinearity within the Chlorella genus, suggesting that centromeric sequence evolves more rapidly than sequence in non-centromeric regions. CONCLUSIONS This study not only provides high-quality genome data for comparative genomics of green algae but gives insight into the composition and evolutionary history of centromeres in early plants, laying an important foundation for further research on their evolution.
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Affiliation(s)
- Bo Wang
- School of Automation Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
- MOE Key Lab for Intelligent Networks & Networks Security, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Yanyan Jia
- School of Automation Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
- MOE Key Lab for Intelligent Networks & Networks Security, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Ningxin Dang
- School of Automation Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
- Genome Institute, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Jie Yu
- College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Stephen J Bush
- School of Automation Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Shenghan Gao
- School of Automation Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Wenxi He
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Sirui Wang
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Hongtao Guo
- School of Computer Science and Technology, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Xiaofei Yang
- School of Computer Science and Technology, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Weimin Ma
- College of Life Sciences, Shanghai Normal University, Shanghai, China.
| | - Kai Ye
- School of Automation Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China.
- MOE Key Lab for Intelligent Networks & Networks Security, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China.
- Genome Institute, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
- Faculty of Science, Leiden University, Leiden, The Netherlands.
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4
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Naish M, Henderson IR. The structure, function, and evolution of plant centromeres. Genome Res 2024; 34:161-178. [PMID: 38485193 PMCID: PMC10984392 DOI: 10.1101/gr.278409.123] [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] [Indexed: 03/22/2024]
Abstract
Centromeres are essential regions of eukaryotic chromosomes responsible for the formation of kinetochore complexes, which connect to spindle microtubules during cell division. Notably, although centromeres maintain a conserved function in chromosome segregation, the underlying DNA sequences are diverse both within and between species and are predominantly repetitive in nature. The repeat content of centromeres includes high-copy tandem repeats (satellites), and/or specific families of transposons. The functional region of the centromere is defined by loading of a specific histone 3 variant (CENH3), which nucleates the kinetochore and shows dynamic regulation. In many plants, the centromeres are composed of satellite repeat arrays that are densely DNA methylated and invaded by centrophilic retrotransposons. In some cases, the retrotransposons become the sites of CENH3 loading. We review the structure of plant centromeres, including monocentric, holocentric, and metapolycentric architectures, which vary in the number and distribution of kinetochore attachment sites along chromosomes. We discuss how variation in CENH3 loading can drive genome elimination during early cell divisions of plant embryogenesis. We review how epigenetic state may influence centromere identity and discuss evolutionary models that seek to explain the paradoxically rapid change of centromere sequences observed across species, including the potential roles of recombination. We outline putative modes of selection that could act within the centromeres, as well as the role of repeats in driving cycles of centromere evolution. Although our primary focus is on plant genomes, we draw comparisons with animal and fungal centromeres to derive a eukaryote-wide perspective of centromere structure and function.
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Affiliation(s)
- Matthew Naish
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
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5
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Hammel A, Neupert J, Bock R. Optimized transgene expression in the red alga Porphyridium purpureum and efficient recombinant protein secretion into the culture medium. PLANT MOLECULAR BIOLOGY 2024; 114:18. [PMID: 38353826 PMCID: PMC10866757 DOI: 10.1007/s11103-024-01415-2] [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: 09/28/2023] [Accepted: 01/02/2024] [Indexed: 02/16/2024]
Abstract
Microalgae represent a promising but yet underexplored production platform for biotechnology. The vast majority of studies on recombinant protein expression in algae have been conducted in a single species, the green alga Chlamydomonas reinhardtii. However, due to epigenetic silencing, transgene expression in Chlamydomonas is often inefficient. Here we have investigated parameters that govern efficient transgene expression in the red microalga Porphyridium purpureum. Porphyridium is unique in that the introduced transformation vectors are episomally maintained as autonomously replicating plasmids in the nucleus. We show that full codon optimization to the preferred codon usage in the Porphyridium genome confers superior transgene expression, not only at the level of protein accumulation, but also at the level of mRNA accumulation, indicating that high translation rates increase mRNA stability. Our optimized expression constructs resulted in YFP accumulation to unprecedented levels of up to 5% of the total soluble protein. We also designed expression cassettes that target foreign proteins to the secretory pathway and lead to efficient protein secretion into the culture medium, thus simplifying recombinant protein harvest and purification. Our study paves the way to the exploration of red microalgae as expression hosts in molecular farming for recombinant proteins and metabolites.
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Affiliation(s)
- Alexander Hammel
- Max-Planck-Institut für Molekulare Pflanzenphysiologie (MPI-MP), Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Juliane Neupert
- Max-Planck-Institut für Molekulare Pflanzenphysiologie (MPI-MP), Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie (MPI-MP), Am Mühlenberg 1, 14476, Potsdam-Golm, Germany.
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6
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Sayer AP, Llavero-Pasquina M, Geisler K, Holzer A, Bunbury F, Mendoza-Ochoa GI, Lawrence AD, Warren MJ, Mehrshahi P, Smith AG. Conserved cobalamin acquisition protein 1 is essential for vitamin B12 uptake in both Chlamydomonas and Phaeodactylum. PLANT PHYSIOLOGY 2024; 194:698-714. [PMID: 37864825 PMCID: PMC10828217 DOI: 10.1093/plphys/kiad564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 08/01/2023] [Accepted: 08/18/2023] [Indexed: 10/23/2023]
Abstract
Microalgae play an essential role in global net primary productivity and global biogeochemical cycling. Despite their phototrophic lifestyle, over half of algal species depend for growth on acquiring an external supply of the corrinoid vitamin B12 (cobalamin), a micronutrient produced only by a subset of prokaryotic organisms. Previous studies have identified protein components involved in vitamin B12 uptake in bacterial species and humans. However, little is known about its uptake in algae. Here, we demonstrate the essential role of a protein, cobalamin acquisition protein 1 (CBA1), in B12 uptake in Phaeodactylum tricornutum using CRISPR-Cas9 to generate targeted knockouts and in Chlamydomonas reinhardtii by insertional mutagenesis. In both cases, CBA1 knockout lines could not take up exogenous vitamin B12. Complementation of the C. reinhardtii mutants with the wild-type CBA1 gene restored B12 uptake, and regulation of CBA1 expression via a riboswitch element enabled control of the phenotype. When visualized by confocal microscopy, a YFP-fusion with C. reinhardtii CBA1 showed association with membranes. Bioinformatics analysis found that CBA1-like sequences are present in all major eukaryotic phyla. In algal taxa, the majority that encoded CBA1 also had genes for B12-dependent enzymes, suggesting CBA1 plays a conserved role. Our results thus provide insight into the molecular basis of algal B12 acquisition, a process that likely underpins many interactions in aquatic microbial communities.
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Affiliation(s)
- Andrew P Sayer
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Marcel Llavero-Pasquina
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Katrin Geisler
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Andre Holzer
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Freddy Bunbury
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Gonzalo I Mendoza-Ochoa
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Andrew D Lawrence
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Martin J Warren
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UA, UK
| | - Payam Mehrshahi
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Alison G Smith
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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7
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Poirier M, Osmers P, Wilkins K, Morgan-Kiss RM, Cvetkovska M. Aberrant light sensing and motility in the green alga Chlamydomonas priscuii from the ice-covered Antarctic Lake Bonney. PLANT SIGNALING & BEHAVIOR 2023; 18:2184588. [PMID: 38126947 PMCID: PMC10012900 DOI: 10.1080/15592324.2023.2184588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 02/20/2023] [Indexed: 12/23/2023]
Abstract
The Antarctic green alga Chlamydomonas priscuii is an obligate psychrophile and an emerging model for photosynthetic adaptation to extreme conditions. Endemic to the ice-covered Lake Bonney, this alga thrives at highly unusual light conditions characterized by very low light irradiance (<15 μmol m-2 s-1), a narrow wavelength spectrum enriched in blue light, and an extreme photoperiod. Genome sequencing of C. priscuii exposed an unusually large genome, with hundreds of highly similar gene duplicates and expanded gene families, some of which could be aiding its survival in extreme conditions. In contrast to the described expansion in the genetic repertoire in C. priscuii, here we suggest that the gene family encoding for photoreceptors is reduced when compared to related green algae. This alga also possesses a very small eyespot and exhibits an aberrant phototactic response, compared to the model Chlamydomonas reinhardtii. We also investigated the genome and behavior of the closely related psychrophilic alga Chlamydomonas sp. ICE-MDV, that is found throughout the photic zone of Lake Bonney and is naturally exposed to higher light levels. Our analyses revealed a photoreceptor gene family and a robust phototactic response similar to those in the model Chlamydomonas reinhardtii. These results suggest that the aberrant phototactic response in C. priscuii is a result of life under extreme shading rather than a common feature of all psychrophilic algae. We discuss the implications of these results on the evolution and survival of shade adapted polar algae.
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Affiliation(s)
| | - Pomona Osmers
- Department of Biology, University of Ottawa, Ottawa, OH, Canada
| | - Kieran Wilkins
- Department of Biology, University of Ottawa, Ottawa, OH, Canada
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8
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Domozych DS, LoRicco JG. The extracellular matrix of green algae. PLANT PHYSIOLOGY 2023; 194:15-32. [PMID: 37399237 PMCID: PMC10762512 DOI: 10.1093/plphys/kiad384] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 07/05/2023]
Abstract
Green algae display a wide range of extracellular matrix (ECM) components that include various types of cell walls (CW), scales, crystalline glycoprotein coverings, hydrophobic compounds, and complex gels or mucilage. Recently, new information derived from genomic/transcriptomic screening, advanced biochemical analyses, immunocytochemical studies, and ecophysiology has significantly enhanced and refined our understanding of the green algal ECM. In the later diverging charophyte group of green algae, the CW and other ECM components provide insight into the evolution of plants and the ways the ECM modulates during environmental stress. Chlorophytes produce diverse ECM components, many of which have been exploited for various uses in medicine, food, and biofuel production. This review highlights major advances in ECM studies of green algae.
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Affiliation(s)
- David S Domozych
- Department of Biology, Skidmore College, Saratoga Springs, NY 12866, USA
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9
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Groussman RD, Blaskowski S, Coesel SN, Armbrust EV. MarFERReT, an open-source, version-controlled reference library of marine microbial eukaryote functional genes. Sci Data 2023; 10:926. [PMID: 38129449 PMCID: PMC10739892 DOI: 10.1038/s41597-023-02842-4] [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: 06/07/2023] [Accepted: 12/08/2023] [Indexed: 12/23/2023] Open
Abstract
Metatranscriptomics generates large volumes of sequence data about transcribed genes in natural environments. Taxonomic annotation of these datasets depends on availability of curated reference sequences. For marine microbial eukaryotes, current reference libraries are limited by gaps in sequenced organism diversity and barriers to updating libraries with new sequence data, resulting in taxonomic annotation of about half of eukaryotic environmental transcripts. Here, we introduce Marine Functional EukaRyotic Reference Taxa (MarFERReT), a marine microbial eukaryotic sequence library designed for use with taxonomic annotation of eukaryotic metatranscriptomes. We gathered 902 publicly accessible marine eukaryote genomes and transcriptomes and assessed their sequence quality and cross-contamination issues, selecting 800 validated entries for inclusion in MarFERReT. Version 1.1 of MarFERReT contains reference sequences from 800 marine eukaryotic genomes and transcriptomes, covering 453 species- and strain-level taxa, totaling nearly 28 million protein sequences with associated NCBI and PR2 Taxonomy identifiers and Pfam functional annotations. The MarFERReT project repository hosts containerized build scripts, documentation on installation and use case examples, and information on new versions of MarFERReT.
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Affiliation(s)
- R D Groussman
- School of Oceanography, University of Washington, Benjamin Hall IRB, Room 306 616 NE Northlake Place, Seattle, WA, 98105, USA.
| | - S Blaskowski
- School of Oceanography, University of Washington, Benjamin Hall IRB, Room 306 616 NE Northlake Place, Seattle, WA, 98105, USA
- Molecular Engineering and Sciences Institute, University of Washington, Molecular Engineering & Sciences Building 3946 W Stevens Way NE, Seattle, WA, 98195, USA
| | - S N Coesel
- School of Oceanography, University of Washington, Benjamin Hall IRB, Room 306 616 NE Northlake Place, Seattle, WA, 98105, USA
| | - E V Armbrust
- School of Oceanography, University of Washington, Benjamin Hall IRB, Room 306 616 NE Northlake Place, Seattle, WA, 98105, USA.
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10
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Chaux F, Jarrige D, Rodrigues-Azevedo M, Bujaldon S, Caspari OD, Ozawa SI, Drapier D, Vallon O, Choquet Y, de Vitry C. Chloroplast ATP synthase biogenesis requires peripheral stalk subunits AtpF and ATPG and stabilization of atpE mRNA by OPR protein MDE1. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:1582-1599. [PMID: 37824282 DOI: 10.1111/tpj.16448] [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: 05/17/2023] [Revised: 08/15/2023] [Accepted: 08/21/2023] [Indexed: 10/14/2023]
Abstract
Chloroplast ATP synthase contains subunits of plastid and nuclear genetic origin. To investigate the coordinated biogenesis of this complex, we isolated novel ATP synthase mutants in the green alga Chlamydomonas reinhardtii by screening for high light sensitivity. We report here the characterization of mutants affecting the two peripheral stalk subunits b and b', encoded respectively by the atpF and ATPG genes, and of three independent mutants which identify the nuclear factor MDE1, required to stabilize the chloroplast-encoded atpE mRNA. Whole-genome sequencing revealed a transposon insertion in the 3'UTR of ATPG while mass spectrometry shows a small accumulation of functional ATP synthase in this knock-down ATPG mutant. In contrast, knock-out ATPG mutants, obtained by CRISPR-Cas9 gene editing, fully prevent ATP synthase function and accumulation, as also observed in an atpF frame-shift mutant. Crossing ATP synthase mutants with the ftsh1-1 mutant of the major thylakoid protease identifies AtpH as an FTSH substrate, and shows that FTSH significantly contributes to the concerted accumulation of ATP synthase subunits. In mde1 mutants, the absence of atpE transcript fully prevents ATP synthase biogenesis and photosynthesis. Using chimeric atpE genes to rescue atpE transcript accumulation, we demonstrate that MDE1, a novel octotricopeptide repeat (OPR) protein, genetically targets the atpE 5'UTR. In the perspective of the primary endosymbiosis (~1.5 Gy), the recruitment of MDE1 to its atpE target exemplifies a nucleus/chloroplast interplay that evolved rather recently, in the ancestor of the CS clade of Chlorophyceae, ~300 My ago.
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Affiliation(s)
- Frédéric Chaux
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Domitille Jarrige
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Marcio Rodrigues-Azevedo
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Sandrine Bujaldon
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Oliver D Caspari
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Shin-Ichiro Ozawa
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Dominique Drapier
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Olivier Vallon
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Yves Choquet
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
| | - Catherine de Vitry
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005, Paris, France
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11
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Back G, Walther D. Predictions of DNA mechanical properties at a genomic scale reveal potentially new functional roles of DNA flexibility. NAR Genom Bioinform 2023; 5:lqad097. [PMID: 37954573 PMCID: PMC10632188 DOI: 10.1093/nargab/lqad097] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 09/28/2023] [Accepted: 10/25/2023] [Indexed: 11/14/2023] Open
Abstract
Mechanical properties of DNA have been implied to influence many of its biological functions. Recently, a new high-throughput method, called loop-seq, which allows measuring the intrinsic bendability of DNA fragments, has been developed. Using loop-seq data, we created a deep learning model to explore the biological significance of local DNA flexibility in a range of different species from different kingdoms. Consistently, we observed a characteristic and largely dinucleotide-composition-driven change of local flexibility near transcription start sites. In the presence of a TATA-box, a pronounced peak of high flexibility can be observed. Furthermore, depending on the transcription factor investigated, flanking-sequence-dependent DNA flexibility was identified as a potential factor influencing DNA binding. Compared to randomized genomic sequences, depending on species and taxa, actual genomic sequences were observed both with increased and lowered flexibility. Furthermore, in Arabidopsis thaliana, mutation rates, both de novo and fixed, were found to be associated with relatively rigid sequence regions. Our study presents a range of significant correlations between characteristic DNA mechanical properties and genomic features, the significance of which with regard to detailed molecular relevance awaits further theoretical and experimental exploration.
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Affiliation(s)
- Georg Back
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm 14476, Germany
| | - Dirk Walther
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm 14476, Germany
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12
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Chaux F, Agier N, Garrido C, Fischer G, Eberhard S, Xu Z. Telomerase-independent survival leads to a mosaic of complex subtelomere rearrangements in Chlamydomonas reinhardtii. Genome Res 2023; 33:1582-1598. [PMID: 37580131 PMCID: PMC10620057 DOI: 10.1101/gr.278043.123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 08/09/2023] [Indexed: 08/16/2023]
Abstract
Telomeres and subtelomeres, the genomic regions located at chromosome extremities, are essential for genome stability in eukaryotes. In the absence of the canonical maintenance mechanism provided by telomerase, telomere shortening induces genome instability. The landscape of the ensuing genome rearrangements is not accessible by short-read sequencing. Here, we leverage Oxford Nanopore Technologies long-read sequencing to survey the extensive repertoire of genome rearrangements in telomerase mutants of the model green microalga Chlamydomonas reinhardtii In telomerase-mutant strains grown for hundreds of generations, most chromosome extremities were capped by short telomere sequences that were either recruited de novo from other loci or maintained in a telomerase-independent manner. Other extremities did not end with telomeres but only with repeated subtelomeric sequences. The subtelomeric elements, including rDNA, were massively rearranged and involved in breakage-fusion-bridge cycles, translocations, recombinations, and chromosome circularization. These events were established progressively over time and displayed heterogeneity at the subpopulation level. New telomere-capped extremities composed of sequences originating from more internal genomic regions were associated with high DNA methylation, suggesting that de novo heterochromatin formation contributes to the restoration of chromosome end stability in C. reinhardtii The diversity of alternative strategies present in the same organism to maintain chromosome integrity and the variety of rearrangements found in telomerase mutants are remarkable, and illustrate genome plasticity at short timescales.
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Affiliation(s)
- Frédéric Chaux
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Nicolas Agier
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Clotilde Garrido
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Gilles Fischer
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Stephan Eberhard
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Zhou Xu
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France;
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13
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Geng S, Hamaji T, Ferris PJ, Gao M, Nishimura Y, Umen J. A conserved RWP-RK transcription factor VSR1 controls gametic differentiation in volvocine algae. Proc Natl Acad Sci U S A 2023; 120:e2305099120. [PMID: 37436957 PMCID: PMC10629530 DOI: 10.1073/pnas.2305099120] [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: 03/29/2023] [Accepted: 06/12/2023] [Indexed: 07/14/2023] Open
Abstract
Volvocine green algae are a model for understanding the evolution of mating types and sexes. They are facultatively sexual, with gametic differentiation occurring in response to nitrogen starvation (-N) in most genera and to sex inducer hormone in Volvox. The conserved RWP-RK family transcription factor (TF) MID is encoded by the minus mating-type locus or male sex-determining region of heterothallic volvocine species and dominantly determines minus or male gametic differentiation. However, the factor(s) responsible for establishing the default plus or female differentiation programs have remained elusive. We performed a phylo-transcriptomic screen for autosomal RWP-RK TFs induced during gametogenesis in unicellular isogamous Chlamydomonas reinhardtii (Chlamydomonas) and in multicellular oogamous Volvox carteri (Volvox) and identified a single conserved ortho-group we named Volvocine Sex Regulator 1 (VSR1). Chlamydomonas vsr1 mutants of either mating type failed to mate and could not induce expression of key mating-type-specific genes. Similarly, Volvox vsr1 mutants in either sex could initiate sexual embryogenesis, but the presumptive eggs or androgonidia (sperm packet precursors) were infertile and unable to express key sex-specific genes. Yeast two-hybrid assays identified a conserved domain in VSR1 capable of self-interaction or interaction with the conserved N terminal domain of MID. In vivo coimmunoprecipitation experiments demonstrated association of VSR1 and MID in both Chlamydomonas and Volvox. These data support a new model for volvocine sexual differentiation where VSR1 homodimers activate expression of plus/female gamete-specific-genes, but when MID is present, MID-VSR1 heterodimers are preferentially formed and activate minus/male gamete-specific-genes.
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Affiliation(s)
- Sa Geng
- Donald Danforth Plant Science Center, St Louis, MO63132
| | - Takashi Hamaji
- Donald Danforth Plant Science Center, St Louis, MO63132
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto606-8502, Japan
- Research and Development Initiative, Chuo University, Bunkyo-ku, Tokyo112-8551, Japan
| | | | - Minglu Gao
- Donald Danforth Plant Science Center, St Louis, MO63132
| | - Yoshiki Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto606-8502, Japan
| | - James Umen
- Donald Danforth Plant Science Center, St Louis, MO63132
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14
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Li Y, Kim EJ, Voshall A, Moriyama EN, Cerutti H. Small RNAs >26 nt in length associate with AGO1 and are upregulated by nutrient deprivation in the alga Chlamydomonas. THE PLANT CELL 2023; 35:1868-1887. [PMID: 36945744 DOI: 10.1093/plcell/koad093] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/14/2023] [Accepted: 02/17/2023] [Indexed: 05/30/2023]
Abstract
Small RNAs (sRNAs) associate with ARGONAUTE (AGO) proteins forming effector complexes with key roles in gene regulation and defense responses against molecular parasites. In multicellular eukaryotes, extensive duplication and diversification of RNA interference (RNAi) components have resulted in intricate pathways for epigenetic control of gene expression. The unicellular alga Chlamydomonas reinhardtii also has a complex RNAi machinery, including 3 AGOs and 3 DICER-like proteins. However, little is known about the biogenesis and function of most endogenous sRNAs. We demonstrate here that Chlamydomonas contains uncommonly long (>26 nt) sRNAs that associate preferentially with AGO1. Somewhat reminiscent of animal PIWI-interacting RNAs, these >26 nt sRNAs are derived from moderately repetitive genomic clusters and their biogenesis is DICER-independent. Interestingly, the sequences generating these >26-nt sRNAs have been conserved and amplified in several Chlamydomonas species. Moreover, expression of these longer sRNAs increases substantially under nitrogen or sulfur deprivation, concurrently with the downregulation of predicted target transcripts. We hypothesize that the transposon-like sequences from which >26-nt sRNAs are produced might have been ancestrally targeted for silencing by the RNAi machinery but, during evolution, certain sRNAs might have fortuitously acquired endogenous target genes and become integrated into gene regulatory networks.
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Affiliation(s)
- Yingshan Li
- School of Biological Sciences and Center for Plant Science Innovation, University of Nebraska-Lincoln, Nebraska-Lincoln, NE 68588-0666, USA
| | - Eun-Jeong Kim
- Department of Life Science, Chung-Ang University, Seoul 06974, Korea
| | - Adam Voshall
- School of Biological Sciences and Center for Plant Science Innovation, University of Nebraska-Lincoln, Nebraska-Lincoln, NE 68588-0666, USA
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Etsuko N Moriyama
- School of Biological Sciences and Center for Plant Science Innovation, University of Nebraska-Lincoln, Nebraska-Lincoln, NE 68588-0666, USA
| | - Heriberto Cerutti
- School of Biological Sciences and Center for Plant Science Innovation, University of Nebraska-Lincoln, Nebraska-Lincoln, NE 68588-0666, USA
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15
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Payne ZL, Penny GM, Turner TN, Dutcher SK. A gap-free genome assembly of Chlamydomonas reinhardtii and detection of translocations induced by CRISPR-mediated mutagenesis. PLANT COMMUNICATIONS 2023; 4:100493. [PMID: 36397679 PMCID: PMC10030371 DOI: 10.1016/j.xplc.2022.100493] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/26/2022] [Accepted: 11/15/2022] [Indexed: 05/04/2023]
Abstract
Genomic assemblies of the unicellular green alga Chlamydomonas reinhardtii have provided important resources for researchers. However, assembly errors, large gaps, and unplaced scaffolds as well as strain-specific variants currently impede many types of analysis. By combining PacBio HiFi and Oxford Nanopore long-read technologies, we generated a de novo genome assembly for strain CC-5816, derived from crosses of strains CC-125 and CC-124. Multiple methods of evaluating genome completeness and base-pair error rate suggest that the final telomere-to-telomere assembly is highly accurate. The CC-5816 assembly enabled previously difficult analyses that include characterization of the 17 centromeres, rDNA arrays on three chromosomes, and 56 insertions of organellar DNA into the nuclear genome. Using Nanopore sequencing, we identified sites of cytosine (CpG) methylation, which are enriched at centromeres. We analyzed CRISPR-Cas9 insertional mutants in the PF23 gene. Two of the three alleles produced progeny that displayed patterns of meiotic inviability that suggested the presence of a chromosomal aberration. Mapping Nanopore reads from pf23-2 and pf23-3 onto the CC-5816 genome showed that these two strains each carry a translocation that was initiated at the PF23 gene locus on chromosome 11 and joined with chromosomes 5 or 3, respectively. The translocations were verified by demonstrating linkage between loci on the two translocated chromosomes in meiotic progeny. The three pf23 alleles display the expected short-cilia phenotype, and immunoblotting showed that pf23-2 lacks the PF23 protein. Our CC-5816 genome assembly will undoubtedly provide an important tool for the Chlamydomonas research community.
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Affiliation(s)
- Zachary L Payne
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Gervette M Penny
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Tychele N Turner
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Susan K Dutcher
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA.
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16
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Bowles AMC, Williamson CJ, Williams TA, Lenton TM, Donoghue PCJ. The origin and early evolution of plants. TRENDS IN PLANT SCIENCE 2023; 28:312-329. [PMID: 36328872 DOI: 10.1016/j.tplants.2022.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 09/23/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Abstract
Plant (archaeplastid) evolution has transformed the biosphere, but we are only now beginning to learn how this took place through comparative genomics, phylogenetics, and the fossil record. This has illuminated the phylogeny of Archaeplastida, Viridiplantae, and Streptophyta, and has resolved the evolution of key characters, genes, and genomes - revealing that many key innovations evolved long before the clades with which they have been casually associated. Molecular clock analyses estimate that Streptophyta and Viridiplantae emerged in the late Mesoproterozoic to late Neoproterozoic, whereas Archaeplastida emerged in the late-mid Palaeoproterozoic. Together, these insights inform on the coevolution of plants and the Earth system that transformed ecology and global biogeochemical cycles, increased weathering, and precipitated snowball Earth events, during which they would have been key to oxygen production and net primary productivity (NPP).
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Affiliation(s)
- Alexander M C Bowles
- School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK; Bristol Palaeobiology Group, School of Biological Sciences and School of Earth Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK.
| | | | - Tom A Williams
- Bristol Palaeobiology Group, School of Biological Sciences and School of Earth Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK
| | - Timothy M Lenton
- Global Systems Institute, University of Exeter, Laver Building, North Park Road, Exeter EX4 4QE, UK
| | - Philip C J Donoghue
- Bristol Palaeobiology Group, School of Biological Sciences and School of Earth Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK.
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17
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Craig RJ, Gallaher SD, Shu S, Salomé PA, Jenkins JW, Blaby-Haas CE, Purvine SO, O’Donnell S, Barry K, Grimwood J, Strenkert D, Kropat J, Daum C, Yoshinaga Y, Goodstein DM, Vallon O, Schmutz J, Merchant SS. The Chlamydomonas Genome Project, version 6: Reference assemblies for mating-type plus and minus strains reveal extensive structural mutation in the laboratory. THE PLANT CELL 2023; 35:644-672. [PMID: 36562730 PMCID: PMC9940879 DOI: 10.1093/plcell/koac347] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 10/12/2022] [Accepted: 12/16/2022] [Indexed: 05/20/2023]
Abstract
Five versions of the Chlamydomonas reinhardtii reference genome have been produced over the last two decades. Here we present version 6, bringing significant advances in assembly quality and structural annotations. PacBio-based chromosome-level assemblies for two laboratory strains, CC-503 and CC-4532, provide resources for the plus and minus mating-type alleles. We corrected major misassemblies in previous versions and validated our assemblies via linkage analyses. Contiguity increased over ten-fold and >80% of filled gaps are within genes. We used Iso-Seq and deep RNA-seq datasets to improve structural annotations, and updated gene symbols and textual annotation of functionally characterized genes via extensive manual curation. We discovered that the cell wall-less classical reference strain CC-503 exhibits genomic instability potentially caused by deletion of the helicase RECQ3, with major structural mutations identified that affect >100 genes. We therefore present the CC-4532 assembly as the primary reference, although this strain also carries unique structural mutations and is experiencing rapid proliferation of a Gypsy retrotransposon. We expect all laboratory strains to harbor gene-disrupting mutations, which should be considered when interpreting and comparing experimental results. Collectively, the resources presented here herald a new era of Chlamydomonas genomics and will provide the foundation for continued research in this important reference organism.
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Affiliation(s)
- Rory J Craig
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, USA
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Sean D Gallaher
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, USA
| | - Shengqiang Shu
- United States Department of Energy, Joint Genome Institute, Berkeley, California 94720, USA
| | - Patrice A Salomé
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
- Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095, USA
| | - Jerry W Jenkins
- HudsonAlpha Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, Alabama 35806, USA
| | - Crysten E Blaby-Haas
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Samuel O Purvine
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, USA
| | - Samuel O’Donnell
- Laboratory of Computational and Quantitative Biology, UMR 7238, CNRS, Institut de Biologie Paris-Seine, Sorbonne Université, Paris 75005, France
| | - Kerrie Barry
- United States Department of Energy, Joint Genome Institute, Berkeley, California 94720, USA
| | - Jane Grimwood
- HudsonAlpha Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, Alabama 35806, USA
| | - Daniela Strenkert
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, USA
| | - Janette Kropat
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
| | - Chris Daum
- United States Department of Energy, Joint Genome Institute, Berkeley, California 94720, USA
| | - Yuko Yoshinaga
- United States Department of Energy, Joint Genome Institute, Berkeley, California 94720, USA
| | - David M Goodstein
- United States Department of Energy, Joint Genome Institute, Berkeley, California 94720, USA
| | - Olivier Vallon
- Unité Mixte de Recherche 7141, CNRS, Institut de Biologie Physico-Chimique, Sorbonne Université, Paris 75005, France
| | - Jeremy Schmutz
- United States Department of Energy, Joint Genome Institute, Berkeley, California 94720, USA
- HudsonAlpha Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, Alabama 35806, USA
| | - Sabeeha S Merchant
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
- Division of Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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18
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Ford SA, Craig RJ, Ness RW. A novel method for identifying Chlamydomonas reinhardtii (Chlorophyta) and closely related species from nature. JOURNAL OF PHYCOLOGY 2023; 59:281-288. [PMID: 36453860 DOI: 10.1111/jpy.13306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
Here, we introduce a new method for efficiently sampling Chlamydomonas reinhardtii and closely related species using a colony PCR-based screen with novel primer sets designed to specifically detect these important model microalgae. To demonstrate the utility of our new method, we collected 130 soil samples from a wide range of habitats in Ontario, Canada and identified 33 candidate algae, which were barcoded by sequencing a region of the rbcL plastid gene. For select isolates, 18S rRNA gene and YPT4 nuclear markers were also sequenced. Based on phylogenetic and haplotype network analyses of these three loci, seven novel isolates were identified as C. reinhardtii, and one additional isolate appeared to be more closely related to C. reinhardtii than any other known species. All seven new C. reinhardtii strains were interfertile with previously collected C. reinhardtii field isolates, validating the effectiveness of our molecular screen.
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Affiliation(s)
- Scott A Ford
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, L5L 1C6, Canada
- Department of Cell & Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada
| | - Rory J Craig
- California Institute for Quantitative Biosciences, University of California, Berkeley, 174 Stanley Hall, Berkeley, California, 94720-3220, USA
| | - Rob W Ness
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, L5L 1C6, Canada
- Department of Cell & Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
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19
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Murbach TS, Glávits R, Jayasena S, Moghadam Maragheh N, Endres JR, Hirka G, Goodman RE, Vértesi A, Béres E, Pasics Szakonyiné I. Toxicology and digestibility of Chlamydomonas debaryana green algal biomass. J Appl Toxicol 2023. [PMID: 36680512 DOI: 10.1002/jat.4438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/29/2022] [Accepted: 01/17/2023] [Indexed: 01/22/2023]
Abstract
There is an economic interest, both for food security and for the non-meat-eating population, in the development of novel, sustainable sources of high-quality protein. The green algae Chlamydomonas reinhardtii has already been developed for this purpose, and the closely related species, Chlamydomonas debaryana, is a complementary source that also presents some additional advantages, such as reduced production cost. To determine whether C. debaryana may have a similar safety profile to that of C. reinhardtii, a wild type strain was obtained, designated TS04 after confirmation of its identity, and subjected to a battery of preclinical studies. Genetic toxicity was evaluated using a bacterial reverse mutation test, an in vitro mammalian chromosomal aberration test, and an in vivo mammalian micronucleus test in a mouse model. No genotoxic potential (e.g., mutagenicity and clastogenicity) was observed in these tests under the employed conditions up to maximum recommended concentrations or doses. To assess general toxicity, a 90-day repeated-dose oral toxicity study was conducted in rats. No mortality or adverse effects were observed, and no target organs were identified up to the maximum feasible dose, due to solubility, of 4,000 mg/kg bw/day. The no-observed-adverse-effect level was determined as the highest dose tested. A digestibility study in simulated gastric fluid was conducted and determined that TS04 has low allergenic potential, exhibiting rapid digestion of proteins. Due to the negative results of our evaluation, it is reasonable to proceed with further development and additional investigations to contribute towards a safety assessment of the proposed use in food for human consumption.
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Affiliation(s)
| | | | - Shyamali Jayasena
- Food Allergy Research and Resource Program (FARRP), Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska, USA
| | - Niloofar Moghadam Maragheh
- Food Allergy Research and Resource Program (FARRP), Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska, USA
| | | | - Gábor Hirka
- Toxi-Coop Zrt., Budapest, Hungary.,Toxi-Coop Zrt., Arácsi út 97, 8230, Balatonfüred, Hungary
| | - Richard E Goodman
- Food Allergy Research and Resource Program (FARRP), Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska, USA
| | - Adél Vértesi
- Toxi-Coop Zrt., Arácsi út 97, 8230, Balatonfüred, Hungary
| | - Erzsébet Béres
- Toxi-Coop Zrt., Arácsi út 97, 8230, Balatonfüred, Hungary
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20
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López-Cortegano E, Craig RJ, Chebib J, Balogun EJ, Keightley PD. Rates and spectra of de novo structural mutations in Chlamydomonas reinhardtii. Genome Res 2023; 33:45-60. [PMID: 36617667 PMCID: PMC9977147 DOI: 10.1101/gr.276957.122] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
Genetic variation originates from several types of spontaneous mutation, including single-nucleotide substitutions, short insertions and deletions (indels), and larger structural changes. Structural mutations (SMs) drive genome evolution and are thought to play major roles in evolutionary adaptation, speciation, and genetic disease, including cancers. Sequencing of mutation accumulation (MA) lines has provided estimates of rates and spectra of single-nucleotide and indel mutations in many species, yet the rate of new SMs is largely unknown. Here, we use long-read sequencing to determine the full mutation spectrum in MA lines derived from two strains (CC-1952 and CC-2931) of the green alga Chlamydomonas reinhardtii The SM rate is highly variable between strains and between MA lines, and SMs represent a substantial proportion of all mutations in both strains (CC-1952 6%; CC-2931 12%). The SM spectra differ considerably between the two strains, with almost all inversions and translocations occurring in CC-2931 MA lines. This variation is associated with heterogeneity in the number and type of active transposable elements (TEs), which comprise major proportions of SMs in both strains (CC-1952 22%; CC-2931 38%). In CC-2931, a Crypton and a previously undescribed type of DNA element have caused 71% of chromosomal rearrangements, whereas in CC-1952, a Dualen LINE is associated with 87% of duplications. Other SMs, notably large duplications in CC-2931, are likely products of various double-strand break repair pathways. Our results show that diverse types of SMs occur at substantial rates, and support prominent roles for SMs and TEs in evolution.
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Affiliation(s)
- Eugenio López-Cortegano
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Rory J. Craig
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom;,California Institute for Quantitative Biosciences, UC Berkeley, Berkeley, California 94720, USA
| | - Jobran Chebib
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Eniolaye J. Balogun
- Department of Ecology and Evolutionary Biology, University of Toronto, Ontario ON M5S 3B2, Canada;,Department of Biology, University of Toronto Mississauga, Mississauga ON L5L 1C6, Canada
| | - Peter D. Keightley
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
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21
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Jebali A, Sanchez MR, Hanschen ER, Starkenburg SR, Corcoran AA. Trait drift in microalgae and applications for strain improvement. Biotechnol Adv 2022; 60:108034. [PMID: 36089253 DOI: 10.1016/j.biotechadv.2022.108034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 08/06/2022] [Accepted: 09/05/2022] [Indexed: 11/29/2022]
Abstract
Microalgae are increasingly used to generate a wide range of commercial products, and there is growing evidence that microalgae-based products can be produced sustainably. However, industrial production of microalgal biomass is not as developed as other biomanufacturing platform technologies. In addition, results of bench-scale research often fail to translate to large-scale or mass production systems. This disconnect may result from trait drift and evolution occurring, through time, in response to unique drivers in each environment, such as cultivation regimes, weather, and pests. Moreover, outdoor and indoor cultivation of microalgae has the potential to impose negative selection pressures, which makes the maintenance of desired traits a challenge. In this context, this review sheds the light on our current understanding of trait drift and evolution in microalgae. We delineate the basics of phenotype plasticity and evolution, with a focus on how microalgae respond under various conditions. In addition, we review techniques that exploit phenotypic plasticity and evolution for strain improvement in view of industrial commercial applications, highlighting associated advantages and shortcomings. Finally, we suggest future research directions and recommendations to overcome unwanted trait drift and evolution in microalgae cultivation.
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Affiliation(s)
- Ahlem Jebali
- New Mexico Consortium, 4200 W. Jemez Road, Los Alamos, NM 87544, USA.
| | - Monica R Sanchez
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA
| | - Erik R Hanschen
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA
| | | | - Alina A Corcoran
- New Mexico Consortium, 4200 W. Jemez Road, Los Alamos, NM 87544, USA
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22
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Lacroux J, Atteia A, Brugière S, Couté Y, Vallon O, Steyer JP, van Lis R. Proteomics unveil a central role for peroxisomes in butyrate assimilation of the heterotrophic Chlorophyte alga Polytomella sp. Front Microbiol 2022; 13:1029828. [PMID: 36353459 PMCID: PMC9637915 DOI: 10.3389/fmicb.2022.1029828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Accepted: 10/05/2022] [Indexed: 09/08/2023] Open
Abstract
Volatile fatty acids found in effluents of the dark fermentation of biowastes can be used for mixotrophic growth of microalgae, improving productivity and reducing the cost of the feedstock. Microalgae can use the acetate in the effluents very well, but butyrate is poorly assimilated and can inhibit growth above 1 gC.L-1. The non-photosynthetic chlorophyte alga Polytomella sp. SAG 198.80 was found to be able to assimilate butyrate fast. To decipher the metabolic pathways implicated in butyrate assimilation, quantitative proteomics study was developed comparing Polytomella sp. cells grown on acetate and butyrate at 1 gC.L-1. After statistical analysis, a total of 1772 proteins were retained, of which 119 proteins were found to be overaccumulated on butyrate vs. only 46 on acetate, indicating that butyrate assimilation necessitates additional metabolic steps. The data show that butyrate assimilation occurs in the peroxisome via the β-oxidation pathway to produce acetyl-CoA and further tri/dicarboxylic acids in the glyoxylate cycle. Concomitantly, reactive oxygen species defense enzymes as well as the branched amino acid degradation pathway were strongly induced. Although no clear dedicated butyrate transport mechanism could be inferred, several membrane transporters induced on butyrate are identified as potential condidates. Metabolic responses correspond globally to the increased needs for central cofactors NAD, ATP and CoA, especially in the peroxisome and the cytosol.
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Affiliation(s)
| | - Ariane Atteia
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France
| | - Sabine Brugière
- Univ Grenoble Alpes, CEA, INSERM, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
| | - Yohann Couté
- Univ Grenoble Alpes, CEA, INSERM, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
| | - Olivier Vallon
- Institut de Biologie Physico-Chimique, UMR7141 CNRS-Sorbonne Université, Paris, France
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23
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Moniruzzaman M, Erazo-Garcia MP, Aylward FO. Endogenous giant viruses contribute to intraspecies genomic variability in the model green alga Chlamydomonas reinhardtii. Virus Evol 2022; 8:veac102. [PMID: 36447475 PMCID: PMC9693826 DOI: 10.1093/ve/veac102] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 08/05/2022] [Accepted: 10/20/2022] [Indexed: 11/14/2023] Open
Abstract
Chlamydomonas reinhardtii is a unicellular eukaryotic alga that has been studied as a model organism for decades. Despite an extensive history as a model system, phylogenetic and genetic characteristics of viruses infecting this alga have remained elusive. We analyzed high-throughput genome sequence data of C. reinhardtii field isolates, and in six we discovered sequences belonging to endogenous giant viruses that reach up to several 100 kb in length. In addition, we have also discovered the entire genome of a closely related giant virus that is endogenized within the genome of Chlamydomonas incerta, the closest sequenced relative of C. reinhardtii. Endogenous giant viruses add hundreds of new gene families to the host strains, highlighting their contribution to the pangenome dynamics and interstrain genomic variability of C. reinhardtii. Our findings suggest that the endogenization of giant viruses may have important implications for structuring the population dynamics and ecology of protists in the environment.
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Affiliation(s)
- Mohammad Moniruzzaman
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, USA
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
| | - Maria P Erazo-Garcia
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, USA
| | - Frank O Aylward
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-Borne Pathogens, Virginia Tech, 981 Kraft Dr, Room 2036, Blacksburg, VA 24060, USA
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24
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Identification and analysis of smORFs in Chlamydomonas reinhardtii. Genomics 2022; 114:110444. [PMID: 35933072 DOI: 10.1016/j.ygeno.2022.110444] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 07/06/2022] [Accepted: 07/31/2022] [Indexed: 11/24/2022]
Abstract
Small open reading frames (smORFs) have been acknowledged as an important partner in organism functions ranging from bacteria to higher eukaryotes. However, lack of investigation of smORFs in green algae, despite their importance in ecology and evolution. We applied bioinformatic analysis, ribosome profiling, and small peptide proteomics to provide a genome-wide and high-confident smORF database in the model green alga Chlamydomonas reinhardtii. The whole genome was screened first to mine potential coding smORFs. Then conservative analysis, ribosome profiling, and proteomics data were processed to identify conserved smORFs and generate translation evidence. The combination of procedures resulted in 2014 smORFs that might exist in the C. reinhardtii genome. The expression of smORFs in Cd treatment suggested that two smORFs might participate in redox reaction, three in inorganic phosphate transport, and one in DNA repair under stress. Our study built a genome-widely database in C. reinhardtii, providing target smORFs for further research.
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25
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Böndel KB, Samuels T, Craig RJ, Ness RW, Colegrave N, Keightley PD. The distribution of fitness effects of spontaneous mutations in Chlamydomonas reinhardtii inferred using frequency changes under experimental evolution. PLoS Genet 2022; 18:e1009840. [PMID: 35704655 PMCID: PMC9239454 DOI: 10.1371/journal.pgen.1009840] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 06/28/2022] [Accepted: 04/13/2022] [Indexed: 12/23/2022] Open
Abstract
The distribution of fitness effects (DFE) for new mutations is fundamental for many aspects of population and quantitative genetics. In this study, we have inferred the DFE in the single-celled alga Chlamydomonas reinhardtii by estimating changes in the frequencies of 254 spontaneous mutations under experimental evolution and equating the frequency changes of linked mutations with their selection coefficients. We generated seven populations of recombinant haplotypes by crossing seven independently derived mutation accumulation lines carrying an average of 36 mutations in the haploid state to a mutation-free strain of the same genotype. We then allowed the populations to evolve under natural selection in the laboratory by serial transfer in liquid culture. We observed substantial and repeatable changes in the frequencies of many groups of linked mutations, and, surprisingly, as many mutations were observed to increase as decrease in frequency. Mutation frequencies were highly repeatable among replicates, suggesting that selection was the cause of the observed allele frequency changes. We developed a Bayesian Monte Carlo Markov Chain method to infer the DFE. This computes the likelihood of the observed distribution of changes of frequency, and obtains the posterior distribution of the selective effects of individual mutations, while assuming a two-sided gamma distribution of effects. We infer that the DFE is a highly leptokurtic distribution, and that approximately equal proportions of mutations have positive and negative effects on fitness. This result is consistent with what we have observed in previous work on a different C. reinhardtii strain, and suggests that a high fraction of new spontaneously arisen mutations are advantageous in a simple laboratory environment.
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Affiliation(s)
- Katharina B. Böndel
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Toby Samuels
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Rory J. Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Rob W. Ness
- Department of Biology, William G. Davis Building, University of Toronto, Mississauga, Canada
| | - Nick Colegrave
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter D. Keightley
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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26
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Sex-linked deubiquitinase establishes uniparental transmission of chloroplast DNA. Nat Commun 2022; 13:1133. [PMID: 35241655 PMCID: PMC8894339 DOI: 10.1038/s41467-022-28807-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 02/09/2022] [Indexed: 12/26/2022] Open
Abstract
Most sexual organisms inherit organelles from one parent, commonly by excluding organelles from the smaller gametes. However, post-mating elimination of organelles derived from one gamete ensures uniparental inheritance, where the underlying mechanisms to distinguish organelles by their origin remain obscure. Mating in Chlamydomonas reinhardtii combines isomorphic plus and minus gametes, but chloroplast DNA from minus gametes is selectively degraded in zygotes. Here, we identify OTU2p (otubain protein 2), encoded in the plus mating-type locus MT+, as the protector of plus chloroplast. Otu2p is an otubain-like deubiquitinase, which prevents proteasome-mediated degradation of the preprotein translocase of the outer chloroplast membrane (TOC) during gametogenesis. Using OTU2p-knockouts and proteasome inhibitor treatment, we successfully redirect selective DNA degradation in chloroplasts with reduced TOC levels regardless of mating type, demonstrating that plus-specific Otu2p establishes uniparental chloroplast DNA inheritance. Our work documents that a sex-linked organelle quality control mechanism drives the uniparental organelle inheritance without dimorphic gametes. Most sexual organisms ensure that organelles are inherited from a single parent. Here, the authors describe OTU2p, a Chlamydomonas deubiquitinase that drives uniparental organelle inheritance without gametic dimorphism by preventing proteasome-mediated degradation exclusively in gametes of the plus mating type.
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27
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Abstract
The repeated evolution of multicellularity across the tree of life has profoundly affected the ecology and evolution of nearly all life on Earth. Many of these origins were in different groups of photosynthetic eukaryotes, or algae. Here, we review the evolution and genetics of multicellularity in several groups of green algae, which include the closest relatives of land plants. These include millimeter-scale, motile spheroids of up to 50,000 cells in the volvocine algae; decimeter-scale seaweeds in the genus Ulva (sea lettuce); and very plantlike, meter-scale freshwater algae in the genus Chara (stoneworts). We also describe algae in the genus Caulerpa, which are giant, multinucleate, morphologically complex single cells. In each case, we review the life cycle, phylogeny, and genetics of traits relevant to the evolution of multicellularity, and genetic and genomic resources available for the group in question. Finally, we suggest routes toward developing these groups as model organisms for the evolution of multicellularity. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- James Umen
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA;
| | - Matthew D Herron
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
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28
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Lindsey CR, Rosenzweig F, Herron MD. Phylotranscriptomics points to multiple independent origins of multicellularity and cellular differentiation in the volvocine algae. BMC Biol 2021; 19:182. [PMID: 34465312 PMCID: PMC8408923 DOI: 10.1186/s12915-021-01087-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/08/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The volvocine algae, which include the single-celled species Chlamydomonas reinhardtii and the colonial species Volvox carteri, serve as a model in which to study the evolution of multicellularity and cellular differentiation. Studies reconstructing the history of this group have by and large relied on datasets of one to a few genes for phylogenetic inference and ancestral character state reconstruction. As a result, volvocine phylogenies lack concordance depending on the number and/or type of genes (i.e., chloroplast vs nuclear) chosen for phylogenetic inference. While multiple studies suggest that multicellularity evolved only once in the volvocine algae, that each of its three colonial families is monophyletic, and that there have been at least three independent origins of cellular differentiation in the group, other studies call into question one or more of these conclusions. An accurate assessment of the evolutionary history of the volvocine algae requires inference of a more robust phylogeny. RESULTS We performed RNA sequencing (RNA-seq) on 55 strains representing 47 volvocine algal species and obtained similar data from curated databases on 13 additional strains. We then compiled a dataset consisting of transcripts for 40 single-copy, protein-coding, nuclear genes and subjected the predicted amino acid sequences of these genes to maximum likelihood, Bayesian inference, and coalescent-based analyses. These analyses show that multicellularity independently evolved at least twice in the volvocine algae and that the colonial family Goniaceae is not monophyletic. Our data further indicate that cellular differentiation arose independently at least four, and possibly as many as six times, within the volvocine algae. CONCLUSIONS Altogether, our results demonstrate that multicellularity and cellular differentiation are evolutionarily labile in the volvocine algae, affirming the importance of this group as a model system for the study of major transitions in the history of life.
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Affiliation(s)
- Charles Ross Lindsey
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Frank Rosenzweig
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Parker H. Petit Institute for Bioengineering and Biosciences, Atlanta, USA
| | - Matthew D Herron
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
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29
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López-Cortegano E, Craig RJ, Chebib J, Samuels T, Morgan AD, Kraemer SA, Böndel KB, Ness RW, Colegrave N, Keightley PD. De Novo Mutation Rate Variation and Its Determinants in Chlamydomonas. Mol Biol Evol 2021; 38:3709-3723. [PMID: 33950243 PMCID: PMC8383909 DOI: 10.1093/molbev/msab140] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
De novo mutations are central for evolution, since they provide the raw material for natural selection by regenerating genetic variation. However, studying de novo mutations is challenging and is generally restricted to model species, so we have a limited understanding of the evolution of the mutation rate and spectrum between closely related species. Here, we present a mutation accumulation (MA) experiment to study de novo mutation in the unicellular green alga Chlamydomonas incerta and perform comparative analyses with its closest known relative, Chlamydomonas reinhardtii. Using whole-genome sequencing data, we estimate that the median single nucleotide mutation (SNM) rate in C. incerta is μ = 7.6 × 10-10, and is highly variable between MA lines, ranging from μ = 0.35 × 10-10 to μ = 131.7 × 10-10. The SNM rate is strongly positively correlated with the mutation rate for insertions and deletions between lines (r > 0.97). We infer that the genomic factors associated with variation in the mutation rate are similar to those in C. reinhardtii, allowing for cross-prediction between species. Among these genomic factors, sequence context and complexity are more important than GC content. With the exception of a remarkably high C→T bias, the SNM spectrum differs markedly between the two Chlamydomonas species. Our results suggest that similar genomic and biological characteristics may result in a similar mutation rate in the two species, whereas the SNM spectrum has more freedom to diverge.
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Affiliation(s)
- Eugenio López-Cortegano
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jobran Chebib
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Toby Samuels
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew D Morgan
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Katharina B Böndel
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, Stuttgart, Germany
| | - Rob W Ness
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Nick Colegrave
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter D Keightley
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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30
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Chaux-Jukic F, O'Donnell S, Craig RJ, Eberhard S, Vallon O, Xu Z. Architecture and evolution of subtelomeres in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2021; 49:7571-7587. [PMID: 34165564 PMCID: PMC8287924 DOI: 10.1093/nar/gkab534] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/01/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
In most eukaryotes, subtelomeres are dynamic genomic regions populated by multi-copy sequences of different origins, which can promote segmental duplications and chromosomal rearrangements. However, their repetitive nature has complicated the efforts to sequence them, analyse their structure and infer how they evolved. Here, we use recent genome assemblies of Chlamydomonas reinhardtii based on long-read sequencing to comprehensively describe the subtelomere architecture of the 17 chromosomes of this model unicellular green alga. We identify three main repeated elements present at subtelomeres, which we call Sultan, Subtile and Suber, alongside three chromosome extremities with ribosomal DNA as the only identified component of their subtelomeres. The most common architecture, present in 27 out of 34 subtelomeres, is a heterochromatic array of Sultan elements adjacent to the telomere, followed by a transcribed Spacer sequence, a G-rich microsatellite and transposable elements. Sequence similarity analyses suggest that Sultan elements underwent segmental duplications within each subtelomere and rearranged between subtelomeres at a much lower frequency. Analysis of other green algae reveals species-specific repeated elements that are shared across subtelomeres, with an overall organization similar to C. reinhardtii. This work uncovers the complexity and evolution of subtelomere architecture in green algae.
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Affiliation(s)
- Frédéric Chaux-Jukic
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Samuel O'Donnell
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3FL, Edinburgh, UK
| | - Stephan Eberhard
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Olivier Vallon
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Zhou Xu
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
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31
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Craig RJ, Yushenova IA, Rodriguez F, Arkhipova IR. An ancient clade of Penelope-like retroelements with permuted domains is present in the green lineage and protists, and dominates many invertebrate genomes. Mol Biol Evol 2021; 38:5005-5020. [PMID: 34320655 PMCID: PMC8557442 DOI: 10.1093/molbev/msab225] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Penelope-like elements (PLEs) are an enigmatic clade of retrotransposons whose reverse transcriptases (RTs) share a most recent common ancestor with telomerase RTs. The single ORF of canonical endonuclease (EN)+ PLEs encodes RT and a C-terminal GIY–YIG EN that enables intrachromosomal integration, whereas EN− PLEs lack EN and are generally restricted to chromosome termini. EN+ PLEs have only been found in animals, except for one case of horizontal transfer to conifers, whereas EN− PLEs occur in several kingdoms. Here, we report a new, deep-branching PLE clade with a permuted domain order, whereby an N-terminal GIY–YIG EN is linked to a C-terminal RT by a short domain with a characteristic CxC motif. These N-terminal EN+ PLEs share a structural organization, including pseudo-LTRs and complex tandem/inverted insertions, with canonical EN+ PLEs from Penelope/Poseidon, Neptune, and Nematis clades, and show insertion bias for microsatellites, but lack canonical hammerhead ribozyme motifs. However, their phylogenetic distribution is much broader. The Naiads, found in numerous invertebrate phyla, can reach tens of thousands of copies per genome. In spiders and clams, Naiads independently evolved to encode selenoproteins containing multiple selenocysteines. Chlamys, which lack the CCHH motif universal to PLE ENs, occur in green algae, spike mosses (targeting ribosomal DNA), and slime molds. Unlike canonical PLEs, RTs of N-terminal EN+ PLEs contain the insertion-in-fingers domain (IFD), strengthening the link between PLEs and telomerases. Additionally, we describe Hydra, a novel metazoan C-terminal EN+ clade. Overall, we conclude that PLE diversity, taxonomic distribution, and abundance are comparable with non-LTR and LTR-retrotransposons.
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Affiliation(s)
- Rory J Craig
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | - Irina A Yushenova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, USA
| | - Fernando Rodriguez
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, USA
| | - Irina R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, USA
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32
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Chaux-Jukic F, O'Donnell S, Craig RJ, Eberhard S, Vallon O, Xu Z. Architecture and evolution of subtelomeres in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2021. [PMID: 34165564 DOI: 10.1101/2021.01.29.428817)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
In most eukaryotes, subtelomeres are dynamic genomic regions populated by multi-copy sequences of different origins, which can promote segmental duplications and chromosomal rearrangements. However, their repetitive nature has complicated the efforts to sequence them, analyse their structure and infer how they evolved. Here, we use recent genome assemblies of Chlamydomonas reinhardtii based on long-read sequencing to comprehensively describe the subtelomere architecture of the 17 chromosomes of this model unicellular green alga. We identify three main repeated elements present at subtelomeres, which we call Sultan, Subtile and Suber, alongside three chromosome extremities with ribosomal DNA as the only identified component of their subtelomeres. The most common architecture, present in 27 out of 34 subtelomeres, is a heterochromatic array of Sultan elements adjacent to the telomere, followed by a transcribed Spacer sequence, a G-rich microsatellite and transposable elements. Sequence similarity analyses suggest that Sultan elements underwent segmental duplications within each subtelomere and rearranged between subtelomeres at a much lower frequency. Analysis of other green algae reveals species-specific repeated elements that are shared across subtelomeres, with an overall organization similar to C. reinhardtii. This work uncovers the complexity and evolution of subtelomere architecture in green algae.
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Affiliation(s)
- Frédéric Chaux-Jukic
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Samuel O'Donnell
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3FL, Edinburgh, UK
| | - Stephan Eberhard
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Olivier Vallon
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Zhou Xu
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
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33
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Eckardt NA, Birchler JA, Brady SM, Buell CR, Leebens-Mack JH, Meyers BC. Focus on the biology of plant genomes. THE PLANT CELL 2021; 33:781-782. [PMID: 33576423 PMCID: PMC8227447 DOI: 10.1093/plcell/koab039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Affiliation(s)
- Nancy A Eckardt
- Senior Editor, The Plant Cell, American Society of Plant Biologists, USA
| | - James A Birchler
- Senior Editor, The Plant Cell, and Division of Biological Sciences, University of Missouri, Columbia, Missouri, 65211, USA
| | - Siobhán M Brady
- Senior Editor, The Plant Cell, and Department of Plant Biology and Genome Center, University of California, Davis, California, 95616, USA
| | - C Robin Buell
- Reviewing Editor, The Plant Cell, and Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
| | - James H Leebens-Mack
- Reviewing Editor, The Plant Cell, and Department of Plant Biology, University of Georgia, Athens, Georgia, 30602, USA
| | - Blake C Meyers
- Editor-in-Chief, The Plant Cell, and Donald Danforth Plant Science Center, Olivette, Missouri 63132, USA, and Division of Plant Sciences, University of Missouri, Columbia, Missouri, 65211, USA
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34
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Osnato M. Comparative genomics in Chlamydomonas: understanding the past, envisioning the future. THE PLANT CELL 2021; 33:790-791. [PMID: 35234969 PMCID: PMC8226282 DOI: 10.1093/plcell/koab034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 01/22/2021] [Indexed: 06/14/2023]
Affiliation(s)
- Michela Osnato
- Assistant Features Editor, The Plant Cell, American Society of Plant Biologists
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