A conserved function of Human DLC3 and Drosophila Cv-c in testis development.

The identification of genes affecting gonad development is essential to understand the mechanisms causing Variations/Differences in Sex Development (DSD). Recently, a DLC3 mutation was associated with male gonadal dysgenesis in 46,XY DSD patients. We have studied the requirement of Cv-c, the Drosophila ortholog of DLC3, in Drosophila gonad development, as well as the functional capacity of DLC3 human variants to rescue cv-c gonad defects. We show that Cv-c is required to maintain testis integrity during fly development. We find that Cv-c and human DLC3 can perform the same function in fly embryos, as flies carrying wild type but not patient DLC3 variations can rescue gonadal dysgenesis, suggesting functional conservation. We also demonstrate that the StART domain mediates Cv-c's function in the male gonad independently from the GAP domain's activity. This work demonstrates a role for DLC3/Cv-c in male gonadogenesis and highlights a novel StART domain mediated function required to organize the gonadal mesoderm and maintain its interaction with the germ cells during testis development.

Computational Approaches to Investigate and Design Lipid-binding Domains for Membrane Biosensing.

Association of proteins with cellular membranes is critical for signaling and membrane trafficking processes. Many peripheral lipid-binding domains have been identified in the last few decades and have been investigated for their specific lipid-sensing properties using traditional in vivo and in vitro studies. However, several knowledge gaps remain owing to intrinsic limitations of these methodologies. Thus, novel approaches are necessary to further our understanding in lipid-protein biology. This review briefly discusses lipid-binding domains that act as specific lipid biosensors and provides a broad perspective on the computational approaches such as molecular dynamics (MD) simulations and machine learning (ML)-based techniques that can be used to study protein-membrane interactions. We also highlight the need for de novo design of proteins that elicit specific lipid-binding properties.

Estimating the accuracy of the MARTINI model towards the investigation of peripheral protein-membrane interactions.

Peripheral membrane proteins play a major role in numerous biological processes by transiently associating with cellular membranes, often with extreme membrane specificity. Because of the short-lived nature of these interactions, molecular dynamics (MD) simulations have emerged as an appealing tool to characterize at the structural level the molecular details of the protein-membrane interface. Transferable coarse-grained (CG) MD simulations, in particular, offer the possibility to investigate the spontaneous association of peripheral proteins with lipid bilayers of different compositions at limited computational cost, but they are hampered by the lack of a reliable a priori estimation of their accuracy and thus typically require a posteriori experimental validation. In this article, we investigate the ability of the MARTINI CG force field, specifically the 3 open-beta version, to reproduce known experimental observations regarding the membrane binding behavior of 12 peripheral membrane proteins and peptides. Based on observations of multiple binding and unbinding events in several independent replicas, we found that, despite the presence of false positives and false negatives, this model is mostly able to correctly characterize the membrane binding behavior of peripheral proteins, and to identify key residues found to disrupt membrane binding in mutagenesis experiments. While preliminary, our investigations suggest that transferable chemical-specific CG force fields have enormous potential in the characterization of the membrane binding process by peripheral proteins, and that the identification of negative results could help drive future force field development efforts.

Role of Guanidinium-Carboxylate Ion Interaction in Enzyme Inhibition with Implications for Drug Design.

Guanidinium cation (Gdm+) interacts strongly with amino acids of different polarities modulating protein structure and function. Using density functional theory calculations and molecular dynamics simulations, we studied the interaction of Gdm+ with carboxylate ions mimicking its interaction with acidic amino acids and explored its effect in enzymatic folding and activity. We show that, in low concentrations, Gdm+ stabilizes carboxylate ion dimers by acting as a bridge between them, thereby reducing the electrostatic repulsion. We further show that this carboxylate-Gdm+-carboxylate interaction can have an effect on the structure-activity relationship in enzymes with active sites containing two acidic residues. Using five enzymes (hen egg white lysozyme, T4 lysozyme, HIV-1 protease, pepsin, and creatine kinase), which have two acidic amino acids in their active sites, we show that, in low concentrations (<0.5 M), Gdm+ strongly binds to the enzyme active site, thereby potentially inhibiting its activity without unfolding it. This can lead to misleading conclusions in experiments, which infer the extent of enzyme unfolding from activity measurements. However, the carboxylate-Gdm+-carboxylate specific interaction can be exploited in drug discovery as drugs based on guanidinium derivatives are already being used to treat various maladies related to muscle weakness, cancer, diabetes etc. Guanidinium derivatives can be designed as potential drug molecules to inhibit activity or functioning of enzymes, which have binding pockets with two acidic residues in close vicinity.