Saturation of thylakoid-associated fatty acids facilitates bioenergetic coupling in a marine diatom allowing for thermal acclimation

Kuan Yu Cheong, Emre Firlar, Lia Ficaro, Maxim Y. Gorbunov, Jason T. Kaelber, Paul G. Falkowski

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

In a rapidly warming world, we ask, “What limits the potential of marine diatoms to acclimate to elevated temperatures?,” a group of ecologically successful unicellular eukaryotic photoautotrophs that evolved in a cooler ocean and are critical to marine food webs. To this end, we examined thermal tolerance mechanisms related to photosynthesis in the sequenced and transformable model diatom Phaeodactylum tricornutum. Data from transmission electron microscopy (TEM) and fatty acid methyl ester-gas chromatography mass spectrometry (FAME-GCMS) suggest that saturating thylakoid-associated fatty acids allowed rapid (on the order of hours) thermal tolerance up to 28.5°C. Beyond this critical temperature, thylakoid ultrastructure became severely perturbed. Biophysical analyses revealed that electrochemical leakage through the thylakoid membranes was extremely sensitive to elevated temperature (Q10 of 3.5). Data suggest that the loss of the proton motive force (pmf) occurred even when heat-labile photosystem II (PSII) was functioning, and saturation of thylakoid-associated fatty acids was active. Indeed, growth was inhibited when leakage of pmf through thylakoid membranes was insufficiently compensated by proton input from PSII. Our findings provide a mechanistic understanding of the importance of rapid saturation of thylakoid-associated fatty acids for ultrastructure maintenance and a generation of pmf at elevated temperatures. To the extent these experimental results apply, the ability of diatoms to generate a pmf may be a sensitive parameter for thermal sensitivity diagnosis in phytoplankton.

Original languageEnglish (US)
Pages (from-to)3133-3144
Number of pages12
JournalGlobal Change Biology
Volume27
Issue number13
DOIs
StatePublished - Jul 2021

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)

Keywords

  • diatom
  • electrochromic shift (ECS)
  • fatty acid
  • photosynthesis
  • proton motive force (pmf)
  • thermal acclimation
  • thermal tolerance
  • thylakoid membrane

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