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Sruthi, C. K.

Publications and source records attributed to Sruthi, C. K..

4 recordsLinked to original sources

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

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

Chemotaxis microsimulation: On the gain in nutrient uptake and bacterial cell division with chemotaxis mechanism

Bacterial swimming alternates between straight runs for several seconds and tumbles into random directions. Chemotactic bacteria remember nutrient sensing history, change tumble frequency to move toward nutrients. A question that has not been addressed is the significance of the nutrition gain and multiplication of bacterial population with chemotaxis mechanism. To quantify these effects, we introduce a microsimulation model, which seamlessly integrates detailed observations and assumptions about single bacterial tumbles, noisy sensing and nutrient uptake for studying up to a few millions of them in a population. We use the model to simulate absorption of nutrients from lysis and agar plates. Contrary to an intuitive feeling that chemotaxis could be useful under nutrient starvation, we see a significant effect only under nutrient rich conditions where bacteria with chemotaxis outgrow their non-chemotactic counterparts by hundreds of times. The model offers the flexibility to study the consequences of newer assumptions, and experimental conditions.\n\nAuthor SummaryChemotaxis is a mechanism that helps bacteria navigate towards nutrients. Several aspects of the mechanism have been well studied over the past 50 years. As most bacterial mechanisms are helpful evolutionarily to survive and to multiply, it would be a natural question to ask how much this swim helps bacteria to gain nutrition and consequently to multiply. However to our knowledge this question has not been asked. We develop a model that integrates bacterial motion, with sensing and nutrient uptake and show that only under nutrient rich conditions this mechanism helps.

biophysics