RT Journal Article
SR Electronic
T1 A two-hit epistasis model prevents core genome disharmony in recombining bacteria
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.03.15.435406
DO 10.1101/2021.03.15.435406
A1 Aidan J. Taylor
A1 Guillaume Méric
A1 Koji Yahara
A1 Ben Pascoe
A1 Leonardos Mageiros
A1 Evangelos Mourkas
A1 Jessica K Calland
A1 Santeri Puranen
A1 Matthew D. Hitchings
A1 Keith A. Jolley
A1 Carolin M. Kobras
A1 Nicola J. Williams
A1 Arnoud H. M. van Vliet
A1 Julian Parkhill
A1 Martin C. J. Maiden
A1 Jukka Corander
A1 Laurence D Hurst
A1 Daniel Falush
A1 Xavier Didelot
A1 David J. Kelly
A1 Samuel K. Sheppard
YR 2022
UL http://biorxiv.org/content/early/2022/05/10/2021.03.15.435406.abstract
AB Recombination of short DNA fragments via horizontal gene transfer (HGT) can both introduce beneficial alleles and create disharmony in coadapted genomes (negative epistasis). Owing to a lack of protracted intragenomic co-evolution, negative epistatic costs of HGT into non-core (accessory) bacterial genomes are likely to be minimal. By contrast, for the core genome, recombination is expected to be rare because disruptive allelic replacement is likely to introduce negative epistasis. Why then is homologous recombination common in the core of bacterial genomes? To understand this enigma, we take advantage of an exceptional model system, the common enteric pathogens Campylobacter jejuni and Campylobacter coli, that are known for very high magnitude interspecies gene flow in the core genome. As expected, HGT does indeed disrupt co-adapted allele pairings (negative epistasis). However, multiple HGT events enable recovery of the recipient genome’s co-adaption between the alleles, even in core metabolism genes (e.g. formate dehydrogenase). These findings demonstrate that, even for complex traits, genetic coalitions can be decoupled, transferred and independently reinstated in a new genetic background. There is a strong resemblance to the two-hit cancer model. Whether it be by multiple mutations or multiple HGT events, immediate harmful effects from an initial event need not preclude adaptive evolution. The fitness peak jumping problem in asexual lineages is thus less of problem than envisaged.Competing Interest StatementThe authors have declared no competing interest.