Biology subjects

Sarafoglou, C.

Publications and source records attributed to Sarafoglou, C..

3 recordsLinked to original sources

bioRxiv2025

Thermodynamic principles govern evolutionary tradeoffs by regulating allostery

Allostery governs biological activities by signaling environmental cues at distal sites, however, the molecular basis for the orchestration and evolution of "the second secret of life" is evanescent. Seminal work sheds light embracing structure- and function-centric approaches, overlooking the widely accepted ensemble allosteric model based on a proteins free-energy landscape and the thermodynamic nature of allostery. Here, we unraveled allosteric regulation and its evolvability by examining energetic funnels of proteins harboring a highly evolvable ancient scaffold. We uncover intricate allosteric connectivities and their coordinated cross-talk to enable the statistical thermodynamic coupling. We decipher universal molecular determinants for the emergence of functions and environmental adaptability. Our integrative biophysical/statistical/evolutionary analysis ties the evolutionary forces via thermodynamic principles and decrypts how tradeoffs are settled at the molecular level. One-Sentence SummaryWe reveal how physical and evolutionary laws shaped the biophysical properties of proteins

biophysics↗

bioRxiv2025

NEXT-FRET: A solution-based smFRET platform to resolve folding intermediates under native conditions

Folding intermediates are promising therapeutic targets in protein misfolding, bacterial virulence, and drug discovery. Yet, directly observing these transient, non-equilibrium states under physiological conditions remains challenging. Here, we introduce NEXT-FRET (Non-Equilibrium miXTure modeling of smFRET), a solution-based single-molecule FRET (smFRET) platform integrating accessible instrumentation and a time-variant Gaussian Mixture Model (tvGMM) to identify folding intermediates without microfluidics, surface tethering, or denaturants. Using maltose-binding protein (MBP) and its biologically relevant precursor (pre-MBP) for benchmarking and validation, we uncover previously elusive intermediates, including a long-hypothesized closed conformation undetected by existing single-molecule and ensemble methods. Furthermore, we demonstrate that chaperones modulate folding landscapes by stabilizing distinct intermediates, some effectively arresting folding progression; a mechanism increasingly recognized as a therapeutic strategy for targeted protein inactivation. Broadly applicable beyond folding, NEXT-FRET provides a generalizable, high-resolution analytical method for resolving transient biomolecular intermediates, offering a screening-compatible platform in biotechnology and elucidating proteostasis collapse in conformational diseases.

biophysics↗

bioRxiv2023

ABCH2 transporter in the first line of defense protects malaria vectors from pyrethroids

Contact insecticides are primarily used for the control of Anopheles malaria vectors. These chemicals penetrate mosquito legs and other appendages, the first barrier to reaching their neuronal targets. An ATP-Binding Cassette transporter from the H family (ABCH2) is highly expressed in Anopheles coluzzii legs, and further induced upon insecticide exposure. RNAi-mediated silencing of the ABCH2 caused a significant increase in deltamethrin mortality compared to control mosquitoes, coincident with a corresponding increase in 14C-deltamethrin penetration. RT-qPCR analysis and immunolocalization revealed that ABCH2 is mainly localized in the legs and head appendages, and more specifically, the apical part of appendage epidermis, underneath the cuticle. To unravel the molecular mechanism underlying the role of ABCH2 in modulating pyrethroid toxicity, two hypotheses were investigated: An indirect role, based on the orthology with other insect ABCH transporters involved with lipid transport and deposition of CHC lipids in Anopheles legs which may increase cuticle thickness, slowing down the penetration rate of deltamethrin; or the direct pumping of deltamethrin out of the organism. Evaluation of the leg cuticular hydrocarbon (CHC) content showed that this was not affected by ABCH2 silencing, indicating this transporter in is not associated with the transport of leg CHCs. Homology-based modeling suggested that the ABCH2 half-transporter adopts a physiological homodimeric state, in line with its ability to hydrolyze ATP in vitro when expressed on its own in insect cells. Docking analysis revealed a deltamethrin pocket on the homodimeric transporter. Furthermore, deltamethrin-induced ATP hydrolysis in ABCH2-expressing cell membranes, further supports that deltamethrin is indeed a ABCH2 substrate. Overall, our findings pinpoint ABCH2 as a key regulator of deltamethrin toxicity.

evolutionary biology↗