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Biology subjects

Prakash, M. K.

Publications and source records attributed to Prakash, M. K..

11 recordsLinked to original sources

Interpretation of Predictions in Drug-Gut Bacteria Interactions Using Machine Learning

Gut bacteria play a crucial role in hosts metabolism. Both antibiotic and non-antibiotic drugs affect the gut bacteria ecosystem, which negatively affects the hosts health. Also, gut bacteria metabolize drugs, making them ineffective to the target. The structure-activity relationship studies of drugs have the scope to make them more effective, efficient, and specific to the target. Previous machine learning studies use the available data to predict the activity of drugs and gut bacteria on each other, but these models lack interpretability. Herein, we study the drug-gut bacteria interaction using interpretable machine learning models. In this study, we identify the most important physicochemical features of the drug, which decide the drug-gut bacteria interactions with each other. One of the key findings of this work is that the higher-positive charged drug molecules can inhibit the growth of gut bacteria more. In contrast, the higher-negative charged drug molecules have higher possibility to get metabolized by gut bacteria.

biophysics↗

Estimation of Interaction and Growth Parameters to Develop a Computational Model for Gut Bacteria

The relevance of gut bacterial balance to human health can not be overemphasized. The gut bacterial balance delicately relies on several factors inherent to the person as well as to the environment. As the volume of evidences for the gut bacterial influence on health and the clinical data on the variance of the bacterial population across cohorts continue to grow exponentially, it is important to develop a theoretical model for gut bacteria. In this work, we suggest a new computational method for estimating the interaction parameters from the cross-sectional data of bacterial abundances in a cohort, without requiring a longitudinal followup. We introduce a nutrient type based bacterial growth model and use the Monte Carlo approach to estimate the matrix of interaction parameters for the 14 major bacterial species. These parameters were used in a comprehensive first-level computational model we developed for the large intestine to understand the patterns of re-establishing balance with different nutrient types.

biophysics↗

Interpreting mutational effects predictions, one substitution at a time

Mutational effects predictions continue to improve in accuracy as advanced artificial intelligence (AI) algorithms are trained on exhaustive experimental data. The next natural questions to ask are if it is now possible to gain insights into which attribute of the mutation contributes how much to the mutational effects, and if one can develop universal rules for mapping the descriptors to mutational effects. In this work, we mainly address the former aspect using a framework of interpretable AI. Relations between the physico-chemical descriptors and their contributions to the mutational effects are extracted by analyzing the data on 29,832 variants from 8 systematic deep-mutational scan studies. It is found that the intuitive dependences of fitness and solubility on the distance of the amino acid from active site could be extracted and quantified. The dependence of the mutational effect contributions on the number of contacts an amino acid has or the BLOSUM score descriptor of the change showed universal trends. Our attempts in the present work to explain the quantitative differences in the dependence on conservation and SASA across proteins were not successful. The work nevertheless brings transparency into the predictions, development of rules, and will hopefully lead to uncovering the universalities among these rules.

biochemistry↗

An integrative model finds comparable contributions to drug resistance from poor drug adherence and adapting bacteria

Antibiotic resistance is a compound effect of several factors in the infection to healing cycle, from molecular factors such as mutation rate of bacteria to habitual behaviors such as adherence to a prescribed drug. Usually each of these factors is modeled separately from biochemistry, evolutionary biology or population health perspectives. To develop an understanding for the drug resistance at a population level, which is of high global significance, it is important to weigh all these factors in an integrated model. We develop RASAID, a model for resistance considering bacterial adaptation, infection spread, population adherence, immunity, and drug dosage. We apply the model to antibiotic resistance in the spread of resistant strains of Streptococcus Pneumoniae (Sp) in a finite community. We analyze the contributions from several factors to resistance, with a goal towards asking how important is the pursuit of newer drug developments relative to improving the awareness about the good practices in drug usage.

pharmacology and toxicology↗

Slow and ad hoc: Unravelling the two features characterizing the development of bacterial resistance to membrane active peptides

Membrane disrupting drugs such as antimicrobial peptides are being considered as a solution to counter the problem of antibiotic resistance. Although it can be intuitively imagined that bacteria will eventually develop resistance to this class of drugs as well, the concern has largely been ignored. Drawing upon the experimental data from the resistance of Staphylococcus aureus to antimicrobial peptides, we theoretically model the membrane adaptation under drug pressure. Using our model, we simulate the serial passage experiments with and without the drug pressure, and use the comparisons with experiments to estimate the unknown kinetic parameters. While the development of resistance to enzyme or membrane targeting drugs are both driven by spontaneous mutations, an additional lysylation step required in the latter slows the development of resistance. By quantifying the tradeoff between the gain in fitness under drug pressure and a loss in growth due to membrane modification, our model shows a fast reversal of membrane composition in drug free conditions, re-sensitizing the bacterium to the drugs.

biophysics↗

One drug multiple targets: An approach to predict drug efficacies on bacterial strains differing in membrane composition

Rational design methodologies such as quantitative structure activity relationships (QSAR) have conventionally focused on screening through several drugs for their activity against a single target, either a bacterial protein or membrane. Recent concerns in drug design such as the development of drug resistance by membrane adaptation, or the undesirable damage to gut microbiota require a paradigm shift in activity prediction. A complementary approach capable of predicting the activity of a single drug against diverse targets, the diversity arising from bacterial adaptation or a heterogeneous composition with other helpful or harmful bacteria, is needed. As a first predictive step towards this goal, we develop a quantitative model for the activity of daptomycin on Streptococcus aureus strains with different membrane compositions, mainly varying in lysylation. The results of the predictions are good, and within the limits of the scarcely available data, hint at an interaction of daptomycin with the inner membrane. The complementary approach may in principle be extended to estimate the activity against gut bacterial membranes, when systematic data can be curated for training the model.

biochemistry↗

Computationally designing antimicrobial peptides for Acinectobacter Baumannii

Acinetobacter Baumannii, which is mostly contracted in hospital stays, has been developing resistance to all available antibiotics, including the last line of drugs, such as carbapenem. Because of its quick adaptation there is an immediate need to design new antibiotics, possibly antimicrobial peptides (AMPs) to which bacteria do not develop resistance easily. Our threefold goal was to curate the available activity of AMPs on the same strain of A. Baumannii, build a neural network model for predicting their activity and use it to rationally pre-screen for lead generation from the thousands of naturally occurring AMPs. By curating and analyzing the recent activity data from 81 AMPs on ATCC 19606 strain, we develop a quantitative AMP activity prediction model. We selected three other models with comparable performance against a test set with known activities. With the goal of inspiring further studies on AMP drug candidates and their rational shortlisting, we made activity predictions for the entire database of AMPs using all the models. To handle the uncertainty of training with a small data set, highlighted peptides which had consistent results from all models.

biochemistry↗

Visualizing Deep Mutational Scan Data

Site-directed and random mutagenesis are biochemical tools to obtain insights into the structure and function of proteins. Recent advances such as deep mutational scan have allowed a complete scan of all the amino acid positions in a protein with each of the 19 possible alternatives. Mapping out the phenotypic consequences of thousands of single point mutations in the same protein is now possible. Visualizing and analysing the rich data offers an opportunity to learn more about the effects of mutations, for a better understanding and engineering of proteins. This work focuses on such visualization analyses applied to the mutational data of TEM-1 {beta}-lactamase. The data is examined in the light of the expected biochemical effects of single point mutations, with the goal of reinforcing or retraining the intuitions. Individual attributes of the amino acid mutations such as the solvent accessible area, charge type change, and distance from the catalytic center capture most of the relevant functional effects. Visualizing the data suggests how combinations of these attributes can be used for a better classification of the effects of mutations, when independently they do not offer a high predictability.

biochemistry↗

Exploring the context of diacidic motif D-E as a signal for unconventional protein secretion in eukaryotic proteins

Unconventional protein secretion (UPS) is an important phenomenon with fundamental implications to cargo export. How eukaryotic proteins transported by UPS are recognized without a conventional signal peptide has been an open question. It was recently observed that a diacidic amino acid motif (ASP-GLU or DE) is necessary for the secretion of superoxide dismutase 1 (SOD1) from yeast under nutrient starvation. Taking cue from this discovery, we explore the hypothesis of whether the diacidic motif DE, which can occur fairly ubiquitously, along with its context, can be a generic signal for unconventional secretion of proteins. Two different definitions of context were evaluated: structural order and charge signature in the neighborhood of DE as one, and the nature of the amino acid insertion ( X) when a D-X-E motif is present, as another. We observe that among the eukaryotic proteins we studied, the odds of the protein being secreted are higher when the DE motif occurs in the disordered region of the protein, with higher hydrophobicity and lower charge or when the insertion X has a propensity for phosphorylation.

cell biology↗

Viral Complexity: Amino acid co-evolution in viral genomes as a possible metric

Viruses are simultaneously simple and complex. Simple because they have barely around ten types of proteins compared to tens of thousands of proteins in bacteria. Complex because amino acid mutation rates are very high, challenging host immune system and drugs. In this work we use the co-evolution of amino acids and the network characteristics that arise out of it to describe the complexity hidden in the multitude of variations in a viral genome. Using large-scale genomic data, the complexity in several viruses was compared. Interestingly, the co-evolutionary relations were primarily intra-protein in avian influenza and inter-protein in HIV-1. The network degree distributions showed two universality classes: a power-law with exponent -1 in HIV-1 and avian-influenza, random co-evolutionary behavior in human flu and dengue, suggesting the co-evolution as one way to statistically classify the complexity in viruses. The observed correlation between the network densities and the strengths on virus Richter scale raises interesting questions on whether it is possible to define the complexity of viruses using their evolutionary networks.

systems biology↗

Deep2Full: Predictive model for complementing phenotypic outcomes in a deep mutational scan using protein sequence and structure information

Large scale mutagenesis experiments are becoming possible owing to the advancement in the sequencing technologies and high throughput screening. Deep mutational scans perform exhaustive single-point muta-tions on a protein and probe their phenotypic effects. Performing a full scan with site-directed mutations of all the amino acid residues in a protein may not be practical, and may not even be required, especially if predictive computational models can be developed. Computational models are however naive to cellular response in the myriads of assay-conditions. In order to develop the realistic paradigm of assay context-aware predictive hybrid models, we combine minimal deep mutational studies with computational models and pre-dict the phenotypic outcomes quantitatively. Structural, sequence and co-evolutionary information along with partial deep mutational scan data was included to capture the phenotypic relevance of the mutations to the specific screening criterion. The model reliably predicts the fitness outcomes of hundreds of randomly selected amino acid mutations in {beta}-lactamase, when the phenotypic fitness data from as few as 15% of the full mutation is available. Interestingly, the predictive capabilities are better with a random set of mutations rather than with a systematic substitution of all amino acids to alanine, asparagine and histidine (ANH). The model can potentially be extended for predicting the phenotypic outcomes at other concentrations of the stressor by carefully analyzing the dose-response curves of a representative set of mutations.\n\nAuthor SummaryMutations are the minor changes in protein sequences, with incommensurately high consequences for their function. Many severe diseases can occur with simple single point mutations. An interesting way of studying these mutations is not to isolate the protein from its natural conditions, but rather study how the fitness of the cell improves or decreases in response to these mutations. Whether it is for understanding disease biology or for bio-engineering applications it is important to quantify the impact of mutations on the cellular fitness. An experimental paradigm has evolved which has improved the ability to sample several hundred thousands of mutation-fitness relations using high throughput screening. However, since these are very specialized experiments, the question is if the number of such experiments required can be minimized, by using computer models to complement the rest of the fitness predictions. In this work we introduce this new paradigm which uses computer model trained on a partial deep mutation scan data, to predict the fitness variations in a full mutations scan that could also be repeated under multiple experimental conditions like drug concentrations.

bioinformatics↗