The economics of organellar gene loss and endosymbiotic gene transfer

<strong>Background</strong> The endosymbiosis of the bacterial progenitors of the mitochondrion and the chloroplast are landmark events in the evolution of life on Earth. While both organelles have retained substantial proteomic and biochemical complexity, this complexity is not reflecte...

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Main Author: Kelly, S
Format: Journal article
Language:English
Published: BioMed Central 2021
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author Kelly, S
author_facet Kelly, S
author_sort Kelly, S
collection OXFORD
description <strong>Background</strong> The endosymbiosis of the bacterial progenitors of the mitochondrion and the chloroplast are landmark events in the evolution of life on Earth. While both organelles have retained substantial proteomic and biochemical complexity, this complexity is not reflected in the content of their genomes. Instead, the organellar genomes encode fewer than 5% of the genes found in living relatives of their ancestors. While many of the 95% of missing organellar genes have been discarded, others have been transferred to the host nuclear genome through a process known as endosymbiotic gene transfer. <br> <strong>Results</strong> Here, we demonstrate that the difference in the per-cell copy number of the organellar and nuclear genomes presents an energetic incentive to the cell to either delete organellar genes or transfer them to the nuclear genome. We show that, for the majority of transferred organellar genes, the energy saved by nuclear transfer exceeds the costs incurred from importing the encoded protein into the organelle where it can provide its function. Finally, we show that the net energy saved by endosymbiotic gene transfer can constitute an appreciable proportion of total cellular energy budgets and is therefore sufficient to impart a selectable advantage to the cell. <br> <strong>Conclusion</strong> Thus, reduced cellular cost and improved energy efficiency likely played a role in the reductive evolution of mitochondrial and chloroplast genomes and the transfer of organellar genes to the nuclear genome.
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spelling oxford-uuid:211ffe84-8550-4a62-a328-d366e8f901962022-03-26T11:31:31ZThe economics of organellar gene loss and endosymbiotic gene transferJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:211ffe84-8550-4a62-a328-d366e8f90196EnglishSymplectic ElementsBioMed Central2021Kelly, S<strong>Background</strong> The endosymbiosis of the bacterial progenitors of the mitochondrion and the chloroplast are landmark events in the evolution of life on Earth. While both organelles have retained substantial proteomic and biochemical complexity, this complexity is not reflected in the content of their genomes. Instead, the organellar genomes encode fewer than 5% of the genes found in living relatives of their ancestors. While many of the 95% of missing organellar genes have been discarded, others have been transferred to the host nuclear genome through a process known as endosymbiotic gene transfer. <br> <strong>Results</strong> Here, we demonstrate that the difference in the per-cell copy number of the organellar and nuclear genomes presents an energetic incentive to the cell to either delete organellar genes or transfer them to the nuclear genome. We show that, for the majority of transferred organellar genes, the energy saved by nuclear transfer exceeds the costs incurred from importing the encoded protein into the organelle where it can provide its function. Finally, we show that the net energy saved by endosymbiotic gene transfer can constitute an appreciable proportion of total cellular energy budgets and is therefore sufficient to impart a selectable advantage to the cell. <br> <strong>Conclusion</strong> Thus, reduced cellular cost and improved energy efficiency likely played a role in the reductive evolution of mitochondrial and chloroplast genomes and the transfer of organellar genes to the nuclear genome.
spellingShingle Kelly, S
The economics of organellar gene loss and endosymbiotic gene transfer
title The economics of organellar gene loss and endosymbiotic gene transfer
title_full The economics of organellar gene loss and endosymbiotic gene transfer
title_fullStr The economics of organellar gene loss and endosymbiotic gene transfer
title_full_unstemmed The economics of organellar gene loss and endosymbiotic gene transfer
title_short The economics of organellar gene loss and endosymbiotic gene transfer
title_sort economics of organellar gene loss and endosymbiotic gene transfer
work_keys_str_mv AT kellys theeconomicsoforganellargenelossandendosymbioticgenetransfer
AT kellys economicsoforganellargenelossandendosymbioticgenetransfer