ORCID Profile
0000-0001-8583-5362
Current Organisation
University of Oxford
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Publisher: Oxford University Press (OUP)
Date: 02-01-2018
DOI: 10.1093/JXB/ERX456
Publisher: Oxford University Press (OUP)
Date: 19-03-2021
Abstract: Rubisco assimilates CO2 to form the sugars that fuel life on earth. Correlations between rubisco kinetic traits across species have led to the proposition that rubisco adaptation is highly constrained by catalytic trade-offs. However, these analyses did not consider the phylogenetic context of the enzymes that were analyzed. Thus, it is possible that the correlations observed were an artefact of the presence of phylogenetic signal in rubisco kinetics and the phylogenetic relationship between the species that were s led. Here, we conducted a phylogenetically resolved analysis of rubisco kinetics and show that there is a significant phylogenetic signal in rubisco kinetic traits. We re-evaluated the extent of catalytic trade-offs accounting for this phylogenetic signal and found that all were attenuated. Following phylogenetic correction, the largest catalytic trade-offs were observed between the Michaelis constant for CO2 and carboxylase turnover (∼21–37%), and between the Michaelis constants for CO2 and O2 (∼9–19%), respectively. All other catalytic trade-offs were substantially attenuated such that they were marginal (& %) or non-significant. This phylogenetically resolved analysis of rubisco kinetic evolution also identified kinetic changes that occur concomitant with the evolution of C4 photosynthesis. Finally, we show that phylogenetic constraints have played a larger role than catalytic trade-offs in limiting the evolution of rubisco kinetics. Thus, although there is strong evidence for some catalytic trade-offs, rubisco adaptation has been more limited by phylogenetic constraint than by the combined action of all catalytic trade-offs.
Publisher: Springer Science and Business Media LLC
Date: 15-09-2017
DOI: 10.1038/S41598-017-11866-X
Abstract: Endosymbiotic relationships between eukaryotic and prokaryotic cells are common in nature. Endosymbioses between two eukaryotes are also known cyanobacterium-derived plastids have spread horizontally when one eukaryote assimilated another. A unique instance of a non-photosynthetic, eukaryotic endosymbiont involves members of the genus Paramoeba , amoebozoans that infect marine animals such as farmed fish and sea urchins. Paramoeba species harbor endosymbionts belonging to the Kinetoplastea, a erse group of flagellate protists including some that cause devastating diseases. To elucidate the nature of this eukaryote-eukaryote association, we sequenced the genomes and transcriptomes of Paramoeba pemaquidensis and its endosymbiont Perkinsela sp. The endosymbiont nuclear genome is ~9.5 Mbp in size, the smallest of a kinetoplastid thus far discovered. Genomic analyses show that Perkinsela sp. has lost the ability to make a flagellum but retains hallmark features of kinetoplastid biology, including polycistronic transcription, trans -splicing, and a glycosome-like organelle. Mosaic biochemical pathways suggest extensive ‘cross-talk’ between the two organisms, and electron microscopy shows that the endosymbiont ingests amoeba cytoplasm, a novel form of endosymbiont-host communication. Our data reveal the cell biological and biochemical basis of the obligate relationship between Perkinsela sp. and its amoeba host, and provide a foundation for understanding pathogenicity determinants in economically important Paramoeba .
Publisher: Wiley
Date: 24-06-2022
DOI: 10.1111/PBI.13864
Abstract: In biological discovery and engineering research, there is a need to spatially and/or temporally regulate transgene expression. However, the limited availability of promoter sequences that are uniquely active in specific tissue‐types and/or at specific times often precludes co‐expression of multiple transgenes in precisely controlled developmental contexts. Here, we developed a system for use in rice that comprises synthetic designer transcription activator‐like effectors (dTALEs) and cognate synthetic TALE‐activated promoters (STAPs). The system allows multiple transgenes to be expressed from different STAPs, with the spatial and temporal context determined by a single promoter that drives expression of the dTALE. We show that two different systems—dTALE1‐STAP1 and dTALE2‐STAP2—can activate STAP‐driven reporter gene expression in stable transgenic rice lines, with transgene transcript levels dependent on both dTALE and STAP sequence identities. The relative strength of in idual STAP sequences is consistent between dTALE1 and dTALE2 systems but differs between cell‐types, requiring empirical evaluation in each case. dTALE expression leads to off‐target activation of endogenous genes but the number of genes affected is substantially less than the number impacted by the somaclonal variation that occurs during the regeneration of transformed plants. With the potential to design fully orthogonal dTALEs for any genome of interest, the dTALE‐STAP system thus provides a powerful approach to fine‐tune the expression of multiple transgenes, and to simultaneously introduce different synthetic circuits into distinct developmental contexts.
Publisher: Wiley
Date: 27-10-2020
DOI: 10.1111/PBI.13487
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Steven Kelly.