Data supporting "UNDERSTANDING LADDERANE LIPIDS PACKING IN ANAMMOX BACTERIA MEMBRANES"

Eukaryotic membranes typically contain saturated and unsaturated fatty acyl chains, while microbial membranes often incorporate aliphatic rings to enhance stability and fluidity under adverse conditions. Anammox bacteria, which convert ammonium and nitrite/nitrate into N2 gas anaerobically, possess unique ladderane lipids with concatenated cyclobutane rings in their anammoxosome membranes, which are essential for their stability and function. Using Density Functional Theory and Molecular Dynamics simulations, we optimised and analysed the interactions of two types of ladderane lipids ([3][3]LA and [5][3]LA) and compared them to those of conventional lipids (DMPC and POPC) in various environments. The results reveal strong London dispersion interactions within ladderane hydrocarbon chains, contributing to dense packing and reduced lateral diffusion in mixed POPC-ladderane membranes. These findings suggest that ladderane lipids play a crucial role in maintaining membrane integrity and stability, potentially impacting molecule permeation and diffusion processes. The study provides insights into the biophysical properties of ladderane-containing membranes, highlighting their unique structural characteristics and interaction dynamics. Supporting Information. (i) AIMall graphs of monomers and heterodimers in n-octanol. (ii) Average values of the ρ(BCP) found for HBs as well as non-covalent interactions found between the aliphatic/non-cyclic portions of the lipid tails or between the cyclic systems of the ladderane tails in the monomers and for the intra- and inter-molecular noncovalent interactions of the homodimers studied at different environments (gas-phase, water and n-octanol); ∇2ρ(BCP), V(r), and G(r) at the BCPs for the non-covalent interactions as well as interaction energies among the two lipid tails for each monomer. (iii) IGM results for monomers and homodimers (calculated isosurfaces and sum of δg resulting from weak inter- and intra-fragment interactions) in different environments. (iv) MD results for membrane models. (v) Deuterium order parameter (SCH) discussion. (vi) The xyz coordinates of DFT optimised monomers and dimers ([3][3]LA monomer in vacuum, [5][3]LA monomer in vacuum, water, and octanol, [5][3]LA dimer in vacuum, water, and octanol, DMPC monomer in vacuum, water, and octanol, and DMPC dimer in vacuum, water, and octanol). (vii) A snapshot of a full MD system of 37% [3][3]LA – 63% POPC with waters and ions in .gro format. (viii) A trajectory of self-assembly of 63% [3][3]LA – 37% POPC membrane (both semiisotropic and isotropic steps) but without waters and ions to reduce the size, these are .pdb topologies with .xtc trajectories. All Supporting Information can be found in https://doi.org/10.5281/zenodo.15719799.