Biology subjects

Cortajarena, A. L.

Publications and source records attributed to Cortajarena, A. L..

3 recordsLinked to original sources

bioRxiv2026

Hydration and H/D exchange-dependent infrared signatures of the GCN4 leucine zipper

Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy of proteins in aqueous solution is often limited by water absorption and other optical artifacts. To overcome these limitations, we evaluated the structural features and hydrogen-deuterium exchange (HDX) kinetics of the -helical protein GCN4 in both hydrated (wet) and vacuum-dried (dry) states. While solvent heavily mask the second-derivative spectra of wet samples, vacuum drying yielded a thin, protein-rich film on the ATR crystal, significantly enhancing the signal-to-noise ratio and resolving the protein features without altering the native structure. Dry-state analysis clearly resolved the Amide I, Amide II, and deuterium-shifted Amide II (1450 cm-1) bands. Notably, second-derivative analysis of the dry spectra of the HDX samples revealed a bimodal Amide I distribution consisting of a stationary band at 1653 cm-1 from the solvent-inaccessible regions and an isotopically sensitive band shifting from 1648 cm-1 to 1644 cm-1 from solvent-accessible regions. These results demonstrate that vacuum-dried ATR-FTIR spectroscopy effectively eliminates solvent masking, providing the spectral clarity required to resolve discrete -helical sub-populations after deuteration.

biochemistry↗

bioRxiv2025

Cardiac fibrosis inhibitor CTPR390 prevents structural and morphological changes in collagen and fibroblasts of engineered human connective tissue

Cardiac fibrosis is a key characteristic of heart failure, with no effective treatment available. Using three-dimensional human models and cutting-edge biotechnology to evaluate new therapies offers a significant advancement. CTPR390, an experimental anti-fibrotic inhibitor targeting Hsp90, has shown success in animal models, but remains unexplored in human cardiac models. This study evaluated a cardiac three-dimensional engineered connective tissue (ECT) model treated with CTPR390, focusing on changes in the extracellular matrix and fibroblasts. Results showed that CTPR390 prevented architectural changes in TGF{beta}1-activated ECT, preserving tissue perimeter, collagen fibers alignment while reducing percentage of structured areas and degree of collagen structuration. Additionally, the treatment reduced cell area of elongated fibroblasts under tension, without changes in the internal rounded cells devoid of tension. Fibroblast recruitment to tension areas was diminished, showing biomechanical behavior similar to control ECT. This treatment also lowered the gene and protein expression of key pro-fibrotic markers. For the first time, advanced biotechnology was employed to detect the detailed structure of tissue fibrosis reduction after administering CTPR390, representing a significant advancement toward clinical application for cardiac fibrosis treatment. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=56 SRC="FIGDIR/small/633162v2_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@1f84961org.highwire.dtl.DTLVardef@19999eeorg.highwire.dtl.DTLVardef@1491286org.highwire.dtl.DTLVardef@5f2968_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

The Strongest Protein Binder is Surprisingly Labile

Bacterial adhesins are cell-surface proteins that anchor to the cell wall of the host, thus initiating infection. The initial step in infection is precisely the binding to fibrinogen (Fg) from human tissue, after which bacteria can colonize the heart valves by the formation of biofilms. The study of this family of proteins is hence essential to develop new strategies to fight bacterial infections. In the case of Staphylococcus aureus, there exists a type of adhesins known as Microbial Surface Components Recognizing Adhesive Matrix Molecules (MSCRAMMs). Here, we focus on one of them, the Clumping Factor A (ClfA), which has been found to bind Fg through the dock-lock-latch (DLL) mechanism. Interestingly, it has recently been discovered that MSCRAMMs proteins employ a catch-bond to withstand forces exceeding 2 nN, making this type of interaction as mechanically strong as a covalent bond. However, whether this strength is an evolved feature characteristic of the bacterial protein or is typical only of the interaction with its partner is not known. Here we combine single-molecule force spectroscopy (smFS), biophysical binding assays and molecular simulations to study the intrinsic mechanical strength of ClfA. We find that despite the extremely high forces required to break its interactions with Fg, ClfA is not by itself particularly strong, in the absence of its human target. Integrating the results from both theory and experiments we dissect contributions to the mechanical stability of this protein.

biophysics↗