Biology subjects

Pandey, D.

Publications and source records attributed to Pandey, D..

9 recordsLinked to original sources

bioRxiv2026

Transmembrane-domain-driven heterodimer assembly licenses integrin head-domain folding in the endoplasmic reticulum

Integrins are a large family of /{beta} heterodimeric receptors whose activation is associated with the extension of the ectodomain and disruption of transient transmembrane domain (TMD) interactions. Whether the TMD interaction serves additional function(s) beyond regulating integrin activation remains unclear. Here, we report that three TMD-disruptive mutations within the integrin {beta}1-subunit activate its function while simultaneously reducing its surface expression. While a Gly744Asn ({beta}1-GN) and Gly744Leu ({beta}1-GL) TMD mutation yielded viable homozygous offspring, the more disruptive Leu748Arg ({beta}1-LR) TMD mutation caused embryonic lethality in mice and drastically reduced {beta}1-integrin surface levels. Cell biology and biochemistry studies revealed that TMD-TMD interactions drive efficient /{beta}-heterodimer assembly, thereby enabling the coupled folding of the ER-luminal {beta}I-domain. Disruption of these TMD interactions leads to endoplasmic reticulum (ER) retention and luminal domain-dependent ER-associated degradation of the monomeric, misfolded {beta}1-subunit. Moreover, mutations that disrupt the /{beta} TMD interaction of multiple integrin classes in humans similarly impair integrin cell surface expression and cause severe loss-of-function diseases. Together, our findings establish that /{beta} TMD association serves a previously unrecognized role in integrin biogenesis by promoting {beta}I-domain folding, preventing premature integrin activation in the ER, and ensuring the proper cell surface expression of activatable integrins.

cell biology↗

bioRxiv2026

Topological Complementarity Predicts Synergistic Drug Pairs in Branched Metabolic Networks.

Drug discovery typically ranks targets by individual sensitivity. Branched metabolic networks, in contrast, have redundant flux routes that buffer single-enzyme inhibition possibly deviating the best target from the most sensitive node. We developed a topology-driven framework for identifying optimal dual-target pairs and applied it to the E. coli folate pathway. A kinetic model of the folate pathway and its extended one-carbon pool showed that single-node inhibition is compensated by flux redistribution. Pairwise synergy scoring, a metric to measure drug-pair potency as compared to single drug, identified DHPS (folP) and DHFR (folA) as a top-ranked complementary pair. Experimental validation in E. coli MG1655 using sulfamethoxazole and trimethoprim confirmed strong dose-dependent synergy at intermediate inhibition and attenuation at saturation. Our results support topological complementarity as a key predictor of combination efficacy and provide a rationale for drug-pair design in branched biosynthetic pathways.

systems biology↗

bioRxiv2026

Adaptive Landscapes of Plasmodium Falciparum Dihydrofolate Reductase Reveal Pathways to Antifolate Resistance

Antifolate resistance in Plasmodium falciparum dihydrofolate reductase (pfDHFR) remains a major challenge for malaria control. To understand how this enzyme maintains function under antifolate selection, we developed PfPATH, a computational framework that integrates mutational fitness measurements, evolutionary interactions, and structural information to map adaptive trajectories. PfPATH adaptive walks reveal that evolution is constrained to a narrow ridge in sequence space defined by a small subset of residues. Most resistance mutations are individually deleterious and become viable only when supported by stabilizing changes, restricting adaptation to a few high-resistance pathways. Structure network analyses show that these mutations do not disrupt the global enzyme architecture but instead reorganize internal communication to preserve catalytic function. Consistent with this, molecular dynamics and free-energy analyses indicate that resistant variants remain stable while sampling a broader ensemble of low-energy conformational substates. Together, these results reveal a narrow and predictable route to antifolate escape.

biophysics↗

bioRxiv2025

AmpC β-lactamases: A Key to Antibiotic Resistance in ESKAPE Pathogens

AmpC {beta}-lactamases (blaAmpC) are one of the important drivers for a high incidence of antimicrobial resistance (AMR) within ESKAPE pathogens, which are a group of bacteria that are the leading cause of hospital-acquired infections. Investigating the presence and characteristics of the blaAmpC is essential for understanding the molecular mechanism of resistance and developing effective strategies to combat AMR. We have investigated the presence of blaAmpC, distribution on plasmids/chromosomes, copy number, amino acid identities/variabilities, and evolutionary characteristics in ESKAPE pathogens. Our analysis indicates 1790 AmpC enzymes in 4713 completely assembled genomes, subdivided into nine different enzyme groups. AmpC is more common in A. baumannii, followed by P. aeruginosa, K. pneumoniae, and Enterobacter spp., but absent in E. faecium and S. aureus. Among the nine AmpC enzyme groups, ACC, ACT, CMH, and MIR are exclusively found in Enterobacter spp., while the largest enzyme group ADC is only present in A. baumannii; PDC and PIB are found only in P. aeruginosa. Phylogenetic analysis revealed significant divergence amongst few enzyme groups and closer evolutionary relationships within others. Functional motif analysis identified conserved catalytic residues across all enzyme groups, except PIB, which demonstrates structural and functional divergence. Because of these variations, PIBs ability to bind cephalosporins decreases while enhancing its activity against carbapenems, hence, we have excluded PIB from further analysis. This is the first detailed report on AmpC in ESKAPE pathogens, which also re-emphasizes the wise use of antibiotics to reduce the rise of AmpC cephalosporins resistance, a significant public health concern. HighlightsO_LIFirst detailed report on ESKAPE blaAmpC localization in chromosomes and plasmids C_LIO_LIblaAmpC is absent in E. faecium & S. aureus but prevalent in other four pathogens C_LIO_LIMost blaAmpC belong to ADC, exclusively present in A. baumannii chromosomes C_LIO_LIInterspecies gene exchange in K. pneumoniae, P. aeruginosa & Enterobacter spp. C_LIO_LIEvolutionary analysis shows recent divergence & possible horizontal gene transfer C_LI

bioinformatics↗

bioRxiv2024

EEG data quality in large scale field studies in India and Tanzania

There is a growing imperative to understand the neurophysiological impact of our rapidly changing and diverse technological, social, chemical, and physical environments. To untangle the multidimensional and interacting effects requires data at scale across diverse populations, taking measurement out of a controlled lab environment and into the field. Electroencephalography (EEG), which has correlates with various environmental factors as well as cognitive and mental health outcomes, has the advantage of both portability and cost-effectiveness for this purpose. However, with numerous field researchers spread across diverse locations, data quality issues and researcher idle time due to insufficient participants can quickly become unmanageable and expensive problems. In programs we have established in India and Tanzania, we demonstrate that with appropriate training, structured teams, and daily automated analysis and feedback on data quality, non-specialists can reliably collect EEG data alongside various survey and assessments with consistently high throughput and quality. Over a 30-week period, research teams were able to maintain an average of 25.6 subjects per week, collecting data from a diverse sample of 7,933 participants ranging from Hadzabe hunter-gatherers to office workers. Furthermore, data quality, computed on the first 2,400 records using two common methods, PREP and FASTER, was comparable to benchmark datasets from controlled lab conditions. Altogether this resulted in a cost per subject of under $50, a fraction of the cost typical of such data collection, opening up the possibility for large-scale programs particularly in low- and middle-income countries. Significance StatementWith wide human diversity, a rapidly changing environment and growing rates of neurological and mental health disorders, there is an imperative for large scale neuroimaging studies across diverse populations that can deliver high quality data and be affordably sustained. Here we demonstrate, across two large-scale field data acquisition programs operating in India and Tanzania, that with appropriate systems it is possible to generate high throughput EEG data of quality comparable to controlled lab settings. With effective costs of under $50 per subject, this opens new possibilities for low- and middle-income countries to implement large-scale programs, and to do so at scales that previously could not be considered.

neuroscience↗

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

The genetic architecture and evolutionary consequences of the human pelvic form

Human pelvic shape has undergone significant evolutionary change since the divergence from the chimpanzee lineage. This transformation, involving the reduction of the pelvic canal size to support bipedal locomotion, is thought to give rise to the obstetrical dilemma, a hypothesis highlighting the mismatch between the large brain size of infants and the narrowed birth canal in females. Empirical evidence for this classic hypothesis has been equivocal, largely due to a lack of sample size and appropriate types of data. To elucidate the genetic underpinnings of pelvic morphology, we applied a deep learning model to 31,115 dual-energy X-ray absorptiometry (DXA) from the UK Biobank, extracting a set of seven pelvic proportion (PP) phenotypes, including measures of the birth canal. All PPs were found to be highly heritable ([~]25-40%) and a genome-wide association study of these traits identified 179 independent loci. Unlike other skeletal proportions including long bone lengths, the subpubic angle associated with the birth canal exhibits a genetic correlation between sexes significantly less than 1, in line with sex-specific reproductive function. PPs were also left-right asymmetric but not heritable and instead associated with handedness. We conducted phenotypic and genetic association analyses to link PPs to 3 facets of the dilemma: locomotion, pelvic floor function and childbirth. Larger birth canal phenotypes were associated with reduced walking pace, decreased risk of back pain, and increased risk of hip osteoarthritis - phenotypes linked to locomotor efficiency. We also observed that a narrower birth canal width was associated with a reduced risk of pelvic floor disorders. When examining childbirth-related outcomes, narrower birth canal phenotypes were associated with increased risk of emergency cesarean sections and obstructed labor due to insufficient dilation, but not obstructed labor due to positioning of the fetus. Finally, we examined whether the dilemma might have been alleviated through evolution. We found no association between any PPs and gestational duration, contrary to the initial prediction by Washburn in 1960. However, we found that the birth weight of the child, a proxy for skull and brain size, was genetically correlated with birth canal width but not with other PPs. Collectively, our study offers fresh insight on a 60-year-old debate in human evolutionary studies. Our results support the idea that the obstetrical dilemma has played a central role in the co-evolution of the human brain and pelvis, while also highlighting the potential role of associated factors such as pelvic floor health.

genetics↗

bioRxiv2023

Understanding natural selection in Holocene Europe using multi-locus genotype identity scans

Ancient DNA (aDNA) has been a revolutionary technology in understanding human history but has not been used extensively to study natural selection as large sample sizes to study allele frequency changes over time have thus far not been available. Here, we examined a time transect of 708 published samples over the past 7,000 years of European history using multi-locus genotype-based selection scans. As aDNA data is affected by high missingness, ascertainment bias, DNA damage, random allele calling, and is unphased, we first validated our selection scan, G12ancient, on simulated data resembling aDNA under a demographic model that captures broad features of the allele frequency spectrum of European genomes as well as positive controls that have been previously identified and functionally validated in modern European datasets on data from ancient individuals from time periods very close to the present time. We then applied our statistic to the aDNA time transect to detect and resolve the timing of natural selection occurring genome wide and found several candidates of selection across the different time periods that had not been picked up by selection scans using single SNP allele frequency approaches. In addition, enrichment analysis discovered multiple categories of complex traits that might be under adaptation across these periods. Our results demonstrate the utility of applying different types of selection scans to aDNA to uncover putative selection signals at loci in the ancient past that might have been masked in modern samples.

genetics↗

bioRxiv2022

Remdesivir, Zidovudine (AZT) and Nevirapine inhibit Chandipura virus replication through high energy interactions with the RdRp domain of the polymerase protein L

Chandipura Virus (CHPV), a rhabdovirus belonging to mononegavirales, is an emerging pathogen in Indian subcontinent. The virus infection causes fever, brain encephalitis among the young children below 14 yrs of age. In recent past, several outbreaks and deaths among children were reported from in India. There are no targeted drugs or vaccines available against CHPV and symptomatic treatments are the only option. In this background, we aimed to investigate the inhibitory effects of some priviously known viral RNA polymerase inhibitor drugs on CHPV replication. First, we examined remdesivir, which is known to inhibit HCV, Ebola and SARS-CoV-2 replication and close structural similarity along with conserved residues in the finger region of RNA dependent RNA polymerase (RdRp) domain is the basis of replication inhibition. Our results showed that remdesivir inhibits CHPV replication in vero E6 cells to a significant level. In this study we have also included non-nucleoside anti-retroviral inhibitor (NNRTI) drug nevirapine, and nucleoside inhibitor (NRTI) drug AZT (Zidovudine) to determine if these are also able to inhibit CHPV replication. Interestingly, we observed inhibition of CHPV replication by both nevirapine and AZT (in the order nevirapine>AZT), albeit to a lesser extent compared to remdesivir. We next performed molecular docking and modeling study to get an insight about the interactions of these drugs with CHPV polymerase protein. Modeling study predicts that remdesivir has most favourable CHPV polymerase binding energy among these three drugs. Both remdesivor and AZT binds near the polymerase active site through interctions with residues in finger and palm regions of RdRp. In contrast, nevirapine binds to the N-terminal domain (NTD) of the RdRp. In summary, we found remdesivir as a potent inhibitor of CHPV. A combination therapy including remdesivir, nevirapine and AZT may be a better drug cocktail to treat CHPV disease. Our findings warrant further studies of these drugs against CHPV in animal models for clinical use in near future.

microbiology↗