Posted: May 04, 2018 9:10 am
A major question in evolutionary cell biology has been how the chromosomal architecture evolved where the essential genes of an organism came to be split across multiple chromosomes. Researchers have now observed this process take place naturally for the first time:
Paper is open access:
Evolution of Genome Architecture in Archaea: Spontaneous Generation of a New Chromosome in Haloferax volcanii
Darya Ausiannikava Laura Mitchell Hannah Marriott Victoria Smith Michelle Hawkins Kira S Makarova Eugene V Koonin Conrad A Nieduszynski Thorsten Allers
Molecular Biology and Evolution, msy075, https://doi.org/10.1093/molbev/msy075 Published: 16 April 2018
The process was fairly straightforward and obvious: One chromosome with multiple Origins-of-replication, splits into two at two loci that doesn't break existing genes. Both fragments retain functional origins-of-replication elements.
Paper is open access:
Evolution of Genome Architecture in Archaea: Spontaneous Generation of a New Chromosome in Haloferax volcanii
Darya Ausiannikava Laura Mitchell Hannah Marriott Victoria Smith Michelle Hawkins Kira S Makarova Eugene V Koonin Conrad A Nieduszynski Thorsten Allers
Abstract
The common ancestry of archaea and eukaryotes is evident in their genome architecture. All eukaryotic and several archaeal genomes consist of multiple chromosomes, each replicated from multiple origins. Three scenarios have been proposed for the evolution of this genome architecture: (1) mutational diversification of a multi-copy chromosome; (2) capture of a new chromosome by horizontal transfer; (3) acquisition of new origins and splitting into two replication-competent chromosomes. We report an example of the third scenario: the multi-origin chromosome of the archaeon Haloferax volcanii has split into two elements via homologous recombination. The newly-generated elements are bona fide chromosomes, because each bears ‘chromosomal’ replication origins, rRNA loci and essential genes. The new chromosomes were stable during routine growth but additional genetic manipulation, which involves selective bottlenecks, provoked further rearrangements. To the best of our knowledge, rearrangement of a naturally-evolved prokaryotic genome to generate two new chromosomes has not been described previously.
Molecular Biology and Evolution, msy075, https://doi.org/10.1093/molbev/msy075 Published: 16 April 2018
The process was fairly straightforward and obvious: One chromosome with multiple Origins-of-replication, splits into two at two loci that doesn't break existing genes. Both fragments retain functional origins-of-replication elements.
- newchrom.png (43.4 KiB) Viewed 2244 times