The Colombo Lab

@lab-colombo.bsky.social

Computational Chemistry and Biology Lab; Proteins and Small Molecules; Always Room for Improvement. Dept. of Chemistry, University of Pavia, Italy

We developed a reproducible protocol to automate the equilibration of mesoscale all-atom lipid vesicles, with systems reaching 150M atoms. Grateful to @lcasalino88.bsky.social and @rommieamaro.bsky.social for their guidance. Code: github.com/matteo-caste... Paper: pubs.acs.org/doi/10.1021/...

ReVesicle: Curation and Equilibration of Lipid Vesicles for Mesoscale Simulations

Molecular dynamics simulations provide essential atomistic insights into the organization and dynamics of complex biological membranes. However, the equilibration of large-scale, curved lipid assemblies at the all-atom level remains a significant challenge. Standard construction approaches, such as wrapping planar bilayers onto spherical meshes, frequently reverberate into structural instabilities, including membrane holes, infiltrated water, lipid flipping, and nonequilibrated densities, which hinder stable production simulations. Here, we present ReVesicle, an iterative equilibration protocol designed to restore and stabilize quasi-spherical lipid vesicles with complex compositions and large dimensions. The proposed protocol combines selective identification and removal of infiltrated water molecules and flipped lipids with short nonequilibrium MD cycles and anisotropic pressure equilibration. These steps are organized into a modular, iterative sequence that progressively recovers bilayer continuity while preserving the vesicle geometry and enabling global density relaxation. Local vacuum-induced stress generated during nonequilibrium phases promotes lipid tail melting and hole curation, while anisotropic equilibration allows relaxation of box dimensions and system density. To demonstrate the robustness of ReVesicle, we applied the protocol to six biologically realistic vesicle systems: synaptic vesicles, plasma membranes, late endosomes, exosomes, mitochondria-derived vesicles, and the HIV-1 lipid envelope. These systems span diameters from 40 to 105 nm and reach total sizes of up to ∼150 million atoms with heterogeneous and asymmetric lipid compositions. Across all cases, ReVesicle consistently converges to continuous, tightly packed bilayers. Structural and biophysical analyses, including vesicle diameter, sphericity, area per lipid, and lipid acyl-chain order parameters, indicate preservation of quasi-spherical geometry and structural integrity. Overall, ReVesicle provides a reproducible framework for equilibrating large, heterogeneous lipid vesicles suitable for downstream all-atom simulations of complex biological environments.

pubs.acs.org

We are looking for someone to join the group as a postdoc to help us with scaling implicit transfer operators. If you are interested in this, please reach out to me through email. Include CV, with publications and brief motivational statement. RTs appreciated!

Out in Cell @cp-cell.bsky.social: Design principles of cell-state-specific enhancers in hematopoiesis 🧬🩸 screen of fully synthetic enhancers in blood progenitors 🤖 AI that creates new cell state specific enhancers 🔍 negative synergies between TFs lead to specificity! www.cell.com/cell/fulltex... 🧵

Design principles of cell-state-specific enhancers in hematopoiesis

Screen of minimalistic enhancers in blood progenitor cells demonstrates widespread dual activator-repressor function of transcription factors (TFs) and enables the model-guided design of cell-state-sp...

cell.com

Our latest paper "Enzyme Enhancement Through Computational Stability Design Targeting NMR-Determined Catalytic Hotspots" now out in JACS @jacs.acspublications.org. Collaboration with Jose M. Sanchez-Ruiz in Granada, among others. pubs.acs.org/doi/full/10....

Enzyme Enhancement Through Computational Stability Design Targeting NMR-Determined Catalytic Hotspots

Enzymes are the quintessential green catalysts, but realizing their full potential for biotechnology typically requires improvement of their biomolecular properties. Catalysis enhancement, however, is often accompanied by impaired stability. Here, we show how the interplay between activity and stability in enzyme optimization can be efficiently addressed by coupling two recently proposed methodologies for guiding directed evolution. We first identify catalytic hotspots from chemical shift perturbations induced by transition-state-analogue binding and then use computational/phylogenetic design (FuncLib) to predict stabilizing combinations of mutations at sets of such hotspots. We test this approach on a previously designed de novo Kemp eliminase, which is already highly optimized in terms of both activity and stability. Most tested variants displayed substantially increased denaturation temperatures and purification yields. Notably, our most efficient engineered variant shows a ∼3-fold enhancement in activity (kcat ∼ 1700 s–1, kcat/KM ∼ 4.3 × 105 M–1 s–1) from an already heavily optimized starting variant, resulting in the most proficient proton-abstraction Kemp eliminase designed to date, with a catalytic efficiency on a par with naturally occurring enzymes. Molecular simulations pinpoint the origin of this catalytic enhancement as being due to the progressive elimination of a catalytically inefficient substrate conformation that is present in the original design. Remarkably, interaction network analysis identifies a significant fraction of catalytic hotspots, thus providing a computational tool which we show to be useful even for natural-enzyme engineering. Overall, our work showcases the power of dynamically guided enzyme engineering as a design principle for obtaining novel biocatalysts with tailored physicochemical properties, toward even anthropogenic reactions.

pubs.acs.org

Read our latest research with the Rasola Lab and @elenapapaleo.bsky.social on how mutations on the mitochondrial protein TRAP1 impact its function and cancer related activities, published with @springernature on Cell Death and Disease in rdcu.be/edidL

Point mutations of the mitochondrial chaperone TRAP1 affect its functions and pro-neoplastic activity

Cell Death & Disease - Point mutations of the mitochondrial chaperone TRAP1 affect its functions and pro-neoplastic activity

rdcu.be