Biology subjects

A, S.

Publications and source records attributed to A, S..

4 recordsLinked to original sources

bioRxiv2024

Navigating the Fitness Landscapes of Plasmodium falciparum Dihydrofolate Reductase: Evolutionary Insights into Antifolate Resistance

The rapid emergence of drug resistance in malaria parasites poses a significant challenge to the efficacy of antifolate treatments. Traditional drug development approaches, which often rely on empirical screening with limited mechanistic insights, tend to overlook the complex evolutionary mechanisms that enable Plasmodium falciparum to evade drug inhibition while preserving enzyme functionality. In this study, we employed computational techniques to investigate the mutational landscape of dihydrofolate reductase (DHFR), focusing on regions essential for enzyme stability and resistance. Our analysis uncovered conserved residues essential for stability, mutation hotspots that enhance adaptability under drug pressure and co-evolving clusters revealing critical functional interdependencies. Through integrated approaches including mutational scanning, epistatic interaction modeling, and fitness trajectory mapping, we elucidated distinct evolutionary pathways that drive resistance. We were able to track the adaptive paths taken by wild-type residues upon mutation, revealing the steps required to reach high-fitness peaks within the rugged fitness landscape. These findings provide valuable insights into the molecular mechanisms of antifolate resistance. We suggest that future drug design should target co-evolving networks and conserved regions to support the development of next-generation therapies to overcome resistance.

biophysics↗

bioRxiv2024

Mapping DHPS Evolvability: Identification of Novel Evolutionarily Critical Sub-Structure through Evolutionary and Structural Analyses of DHPS

Protein evolution shapes pathogen adaptation-landscape, particularly in developing drug resistance. The rapid evolution of target proteins under antibiotic pressure leads to escape mutations leading to the problem of antibiotic resistance. A deep understanding of the evolutionary dynamics of antibiotic target proteins presents a plausible intervention strategy for disrupting the evolutionary trajectory of resistance. Mutations in Dihydropteroate synthase (DHPS), an essential folate pathway protein and a key target for sulfonamide antibiotics, result in reduced antibiotic binding, leading to resistance. Deploying an array of statistical analyses on the DHPS sequence-space and integrating those with deep mutational analysis and structure-based network-topology models we identified critical DHPS-subsequences. Our analysis of the frustration landscape of DHPS predicts how conformational and mutational changes shift the energy distributions within the DHPS substructures. Combining dimensionality reduction and optimality analysis we identified a substructure critical to DHPS evolvability, and computed its druggablity. Our integrated evolution and structure-informed framework identified a DHPS-substructure with significant evolutionary and structural impact. Targeting this region could constrain DHPS evolvability and disrupt the resistome, presenting a new avenue for antibiotic development and contributing to the broader effort to address the problem of antibiotic resistance.

biophysics↗

bioRxiv2023

Non-viral CRISPR/Cas9 Mutagenesis for Streamlined Generation of Mouse Lung Cancer Models

Functional analysis in mouse models is necessary to establish the involvement of a set of genetic variations in tumor development. Many lung cancer models have been developed using genetic techniques to create gain- or loss-of-function alleles in genes involved in tumorigenesis; however, because of their labor- and time-intensive nature, these models are not suitable for quick and flexible hypothesis testing. Here we introduce a lung mutagenesis platform that utilizes CRISPR/Cas9 RNPs delivered via cationic polymers. This approach allows for the simultaneous inactivation of multiple genes. We validate the effectiveness of this system by targeting a group of tumor suppressor genes, specifically Rb1, Rbl1, Pten, and Trp53, which were chosen for their potential to cause lung tumors, namely Small Cell Lung Carcinoma (SCLC). This polymer-based delivery platform enables the modeling of lung tumorigenesis independently of the genetic background, thus simplifying and expediting the process without the need for modifying the mouse germline or creating custom viral vectors. SignificanceThe development of models to rapidly introduce gene mutations into lung tissue to study their impact on tumor growth is critical for advancing the functional genomics of lung cancer. While previous methods using viral vectors and genetic manipulation in mice have been time-consuming and expensive, here we describe a new technique using cationic polymers as non-viral carriers for CRISPR/Cas9 delivery to induce cancer driving mutations that streamlines this process. This approach mimics natural mutations in lung cancer and accelerates the generation of accurate tumor models. Our study demonstrates the effectiveness of this method in generating small cell lung cancer (SCLC) by modifying four tumor suppressor genes in different mouse genetic backgrounds. This innovative strategy holds promise for faster and more cost-effective cancer modeling. Graphical AbstracSmall Cell Lung Cancer (SCLC) tumors are rapidly generated in any mouse genetic background by using cationic polymers to simultaneously deliver Cas9 and gRNAs targeting the Rb1, Rbl1, Pten and Trp53 tumor-suppressor genes to the adult airway respiratory system in vivo. Addition of the frt guide in the RC::FLTG mice provides a tdTomato gene editing reporter. This study shows the feasibility of rapidly generating lung cancer mouse models via somatic genome engineering through delivery of all CRISPR components in the form of nanoparticles. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/572771v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@d12eeeorg.highwire.dtl.DTLVardef@160472corg.highwire.dtl.DTLVardef@1e0c371org.highwire.dtl.DTLVardef@13f33c1_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Plant-on-Chip: core morphogenesis processes in the tiny plant Wolffia australiana

A plant can be thought of as a colony comprising numerous growth buds, each developing to its own rhythm. Such lack of synchrony impedes efforts to describe core principles of plant morphogenesis, dissect the underlying mechanisms, and identify regulators. Here, we use the tiniest known angiosperm to overcome this challenge and provide an ideal model system for plant morphogenesis. We present a detailed morphological description of the monocot Wolffia australiana, as well as high-quality genome information. Further, we developed the Plant-on-Chip culture system and demonstrate the application of advanced technologies such as snRNA-seq, protein structure prediction, and gene editing. We provide proof-of-concept examples that illustrate how W. australiana can open a new horizon for deciphering the core regulatory mechanisms of plant morphogenesis. SignificanceWhat is the core morphogenetic process in angiosperms, a plant like a tree indeterminately growing, or a bud sequentially generating limited types of organs? Wolffia australiana, one of the smallest angiosperms in the world may help to make a distinction. Wolffia plantlet constitutes of only three organs that are indispensable to complete life cycle: one leaf, one stamen and one gynoecium. Before the growth tip is induced to flower, it keeps branching from the leaf axil and the branches separate from the main plantlet. Here we present a high-quality genome of W. australiana, detailed morphological description, a Plant-on-Chip cultural system, and some principle-proof experiments, demonstrating that W. australiana is a promising model system for deciphering core developmental program in angiosperms.

plant biology↗