Membrane Homeoviscous Adaptation in Sinorhizobium Submitted to a Stressful Thermal Cycle Contributes to the Maintenance of the Symbiotic Plant–Bacteria Interaction

BIASUTTI, MARÍA ALICIA; PAULUCCI, NATALIA SOLEDAD; DARDANELLI, MARTA SUSANA; CESARI, ADRIANA BELÉN; PERILLO, MARÍA ANGÉLICA

Frontiers in Microbiology

Frontiers media

Año: 2021 vol. 12 p. 1 - 13

Here, we estimate fast changes in the fluidity of Sinorhizobium meliloti membranessubmitted to cyclic temperature changes (10◦C?40◦C?10◦C) by monitoring thefluorescence polarization (P) of DPH and TMA-DPH of the whole cell (WC) as well as inits outer (OM) and inner (IM) membranes. Additionally, the long-term response to thermalchanges is demonstrated through the dynamics of the phospholipid and fatty acidcomposition in each membrane. This allowed membrane homeoviscous adaptation bythe return to optimal fluidity levels as measured by the PDPH/TMA-DPH in WC, OM, IM,and multilamellar vesicles of lipids extracted from OM and IM. Due to probe-partitioningpreferences and membranes? compositional characteristics, DPH and TMA-DPH exhibitdifferent behaviors in IM and OM. The rapid effect of cyclic temperature changes on theP was the opposite in both membranes with the IM being the one that exhibited thethermal behavior expected for lipid bilayers. Interestingly, only after the incubation at40◦C, cells were unable to recover the membrane preheating P levels when cooledup to 10◦C. Solely in this condition, the formation of threads and nodular structuresin Medicago sativa infected with S. meliloti were delayed, indicating that the symbioticinteraction was partially altered but not halted