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Fundamental shift in vitamin B12 eco-physiology of a model alga demonstrated by experimental evolution

Research output: Contribution to journalArticle

  • Katherine E. Helliwell
  • Sinéad Collins
  • Elena Kazamia
  • Saul Purton
  • Glen L. Wheeler
  • Alison G. Smith

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Original languageEnglish
Pages (from-to)1446-1455
Number of pages10
JournalThe ISME Journal
Volume9
Issue number6
DOIs
Publication statusPublished - 19 Dec 2014

Abstract

A widespread and complex distribution of vitamin requirements exists over the entire tree of life, with many species having evolved vitamin dependence, both within and between different lineages. Vitamin availability has been proposed to drive selection for vitamin dependence, in a process that links an organism's metabolism to the environment, but this has never been demonstrated directly. Moreover, understanding the physiological processes and evolutionary dynamics that influence metabolic demand for these important micronutrients has significant implications in terms of nutrient acquisition and, in microbial organisms, can affect community composition and metabolic exchange between coexisting species. Here we investigate the origins of vitamin dependence, using an experimental evolution approach with the vitamin B 12 -independent model green alga Chlamydomonas reinhardtii. In fewer than 500 generations of growth in the presence of vitamin B 12, we observe the evolution of a B 12 -dependent clone that rapidly displaces its ancestor. Genetic characterization of this line reveals a type-II Gulliver-related transposable element integrated into the B 12 -independent methionine synthase gene (METE), knocking out gene function and fundamentally altering the physiology of the alga.

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