An unbiased genome-wide view of the mutation rate and spectrum of the endosymbiotic bacterium teredinibacter turnerae

Marcus V.X. Senra, Way Sung, Matthew Ackerman, Samuel F. Miller, Michael Lynch, Carlos Augusto G. Soares

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Mutations contribute to genetic variation in all living systems. Thus, precise estimates of mutation rates and spectra across a diversity of organisms are required for a full comprehension of evolution. Here, a mutation-accumulation (MA) assay was carried out on the endosymbiotic bacterium Teredinibacter turnerae. After 3,025 generations, base-pair substitutions (BPSs) and insertion–deletion (indel) events were characterized by whole-genome sequencing analysis of 47 independent MA lines, yielding a BPS rate of 1.14 109 per site per generation and indel rate of 1.55 1010 events per site per generation, which are among the highest within free-living and facultative intracellular bacteria. As in other endosymbionts, a significant bias of BPSs toward A/T and an excess of deletion mutations over insertion mutations are observed for these MA lines. However, even with a deletion bias, the genome remains relatively large (5.2 Mb) for an endosymbiotic bacterium. The estimate of the effective population size (Ne) in T. turnerae is quite high and comparable to free-living bacteria (4.5 107), suggesting that the heavy bottlenecking associated with many endosymbiotic relationships is not prevalent during the life of this endosymbiont. The efficiency of selection scales with increasing Ne and such strong selection may have been operating against the deletion bias, preventing genome erosion. The observed mutation rate in this endosymbiont is of the same order of magnitude of those with similar Ne, consistent with the idea that population size is a primary determinant of mutation-rate evolution within endosymbionts, and that not all endosymbionts have low Ne

Original languageEnglish (US)
Pages (from-to)723-730
Number of pages8
JournalGenome biology and evolution
Volume10
Issue number3
DOIs
StatePublished - 2018

Keywords

  • Drift-barrier hypothesis.
  • Endosymbiosis
  • Mutation-accumulation (MA) assay
  • Teredinibacter turnerae

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics

Fingerprint Dive into the research topics of 'An unbiased genome-wide view of the mutation rate and spectrum of the endosymbiotic bacterium teredinibacter turnerae'. Together they form a unique fingerprint.

  • Cite this