Novel Intact Polar and Core Lipid Compositions in the Pyrococcus Model Species, P. furiosus and P. yayanosii, Reveal the Largest Lipid Diversity Amongst Thermococcales

Abstract

Elucidating the lipidome of Archaea is essential to understand their tolerance to extreme environmental conditions. Previous characterizations of the lipid composition of Pyrococcus species, a model genus of hyperthermophilic archaea belonging to the Thermococcales order, led to conflicting results, which hindered the comprehension of their membrane structure and the putative adaptive role of their lipids. In an effort to clarify the lipid composition data of the Pyrococcus genus, we thoroughly investigated the distribution of both the core lipids (CL) and intact polar lipids (IPL) of the model Pyrococcus furiosus and, for the first time, of Pyrococcus yayanosii, the sole obligate piezophilic hyperthermophilic archaeon known to date. We showed a low diversity of IPL in the lipid extract of P. furiosus, which nonetheless allowed the first report of phosphatidyl inositol-based glycerol mono- and trialkyl glycerol tetraethers. With up to 13 different CL structures identified, the acid methanolysis of Pyrococcus furiosus revealed an unprecedented CL diversity and showed strong discrepancies with the IPL compositions reported here and in previous studies. By contrast, P. yayanosii displayed fewer CL structures but a much wider variety of polar heads. Our results showed severe inconsistencies between IPL and CL relative abundances. Such differences highlight the diversity and complexity of the Pyrococcus plasma membrane composition and demonstrate that a large part of its lipids remains uncharacterized. Reassessing the lipid composition of model archaea should lead to a better understanding of the structural diversity of their lipidome and of their physiological and adaptive functions.

Characterisation of a synthetic Archeal membrane reveals a possible new adaptation route to extreme conditions

“…Second, membrane lipid compositions in natural membranes are very finely tuned, which may generate important composition variations in the different batches of purified natural lipids. Furthermore, these variations may stay unnoticed since not all polar headgroups are accessible to analysis 28 , but may still impact membrane parameters. Third, in contrast, using synthetic lipids allows for a precise modelization of the data, and for a precise allocation of the molecular interactions, better describing the behavior of the architecture as a function of the parameters tested.…”

Membrane adaptation in the hyperthermophilic archaeon Pyrococcus furiosus relies upon a novel strategy involving glycerol monoalkyl glycerol tetraether lipids

“…The copyright holder for this preprint this version posted November 17, 2021. ; https://doi.org/10.1101/2021.11.17.468962 doi: bioRxiv preprint (Tourte, et al, 2020a). Although no adaptive response could be detected for diether core lipids in the case of P. furiosus, the possibility that diether lipids could respond through the alteration of their polar head groups cannot be ruled out.…”

“…As numerous biotic parameters have been shown to impact lipid compositions (e.g., growth stage (Elling et al, 2014)), growth was tightly monitored (refer to Table S1 for growth measurements under the conditions tested here) and cultures were all inoculated at a cell density of 10 5 cell ml -1 and harvested in late log phase so as to limit the influence of other parameters on the lipid compositions observed. P. furiosus DSM3638 was previously shown to produce at least 14 different core lipid structures (Figure S1) under optimal growth conditions, i.e., in Thermococcales rich medium (TRM) at 98 °C and pH 6.8, with 3 % w/v NaCl and 10 g L -1 of elemental sulfur (Tourte et al, 2020a). Nine core structures, i.e., (which was not certified by peer review) is the author/funder.…”

“…The copyright holder for this preprint this version posted November 17, 2021. ; https://doi.org/10.1101/2021.11.17.468962 doi: bioRxiv preprint investigations of P. furiosus membrane content revealed a unique lipid composition (Figure S1). While it exhibits a limited diversity of polar head groups, i.e., phosphoinositol and a few derivatives (Sprott et al, 1997;Lobasso et al, 2012;Tourte et al, 2020a), those are attached to as many as 14 different core structures, namely DGD, GDGT with 0 to 4 cyclopentane rings (GDGT0-4, respectively), GTGT with 0 to 2 cyclopentane rings (GTGT0-2, respectively), and GMGT with 0 to 4 cyclopentane rings (GMGT0-4) (Tourte et al, 2020a) (Figure S1), paving the way for the elucidation of uncommon membrane adaptive strategies. Indeed, we show here that P. furiosus modulates the ratio of GMGT/GDGT and marginally regulates the number of cyclopentane rings instead of altering the diether/tetraether ratio as most other Archaea do, to respond to temperature, pH, salinity, the presence/absence of elemental sulfur, growth medium, and genetic background.…”

The exploration of Thermococcus barophilus lipidome reveals the widest variety of phosphoglycolipids in Thermococcales

“…IPLs were extracted using a modified Bligh and Dyer (B&D) procedure (39), as previously described (40). Briefly, dried cells were extracted with a monophasic mixture of methanol/dichloromethane/purified water (MeOH/DCM/H 2 O; 1:2.6:0.16; v/v/v) using a sonication probe for 15 min.…”