Projects in our lab
Current projects in the lab focus on exploring interactions that exists within biological systems. We are using microbial vitamin biosynthesis and utilization pathways to probe enzyme-substrate, enzyme-enzyme and microbe-microbe interactions.
Unlocking the complexity and immense interconnectedness of the scientific mechanisms which dictate the properties and processes of the natural world is a major goal of the ABH lab. To this end, we seek to acquire a detailed understanding of many systems and how these various systems function together to generate the observations and measurements from our experimentation. Have a look at some of our projects below.
The anaerobic biosynthesis of Vitamin B12 involves the bza operon, which contains three methyltransferases BzaC, BzaD, and BzaE, each with a unique function. We are currently exploring the mechanisms of each of these three enzymes which have distinct domains and co-factor requirements. Additionally, the mechanistic enzymology of BzaD and BzaE is unprecedented in biological chemistry.
Mechanistic enzymology of the anaerobic biosynthesis of the lower ligand of vitamin B12
Cross-feeding of Vitamin B1 and intermediates in its biosynthetic pathways in synthetic microbial communities
Many ecosystems are composed of consortia of microbes, many of which are auxotrophic for the synthesis of essential biomolecules, that is, they are unable to synthesize them. Vitamins such as B1, B7 and B12 are amongst the repertoire of such critical metabolites that often get exchanged in the gut and marine microbial communities.
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The modular nature of the vitamin B1 (thiamin) biosynthesis allows for such auxotrophies to be commonly observed in nature. So far, the exchange of the key intermediates in this pathway
has not been studied systematically. We thus set up synthetic co-cultures of the thiamin biosynthesis mutants of Escherichia coli to investigate the exchange of B1 biosynthesis intermediates. We also look at the changing co-culture dynamics, in terms of the microbes and the concentrations of the intermediates involved.
Investigating the molecular basis of nucleobase specificity in nucleotide-utilizing enzymes
Phosphorylation reactions in biological chemistry typically utilize a nucleotide triphosphate. For example, ATP is a commonly used substrate for kinase enzymes. However, the phosphorylation reaction involves only the use of the triphosphate part of the molecule - the
role of the specific nucleobase, adenine in this case, is not apparent. Additionally, vitamins such as SAM, flavin adenine dinucleotide, and Coenzyme A contain the nucleobase adenine. We are currently investigating the specificity aspect of the nucleobase in enzyme catalysis and biological chemistry.
Easy evaluation of vitamin concentrations: an HEFA funded initiative to improve vitamin literacy
Promoting vitamin literacy among the general public is hindered by the lack of effective communication regarding their biosynthesis and reliable methods for assessing the concentrations of these essential micronutrients in our daily diets. While the significance of vitamins is widely recognized, accessible and reliable quantitative information is still lacking. This project, funded by the Higher Education Financing Agency (HEFA), aims to provide standardized and easy-to-conduct
biological tests (bioassays) for determining the range of vitamin (B1, B3, B6, B7, and B12) concentration present. These tests will be designed in a manner that offers compatibility with a variety of settings, ideally enabling individuals to perform them in the comfort of their own homes.
Investigating the structure-sequence relationship in homologs of 3-mercaptopyruvate sulfurtransferase to probe their role in developing antibiotic resistance in pathogenic bacteria
Sulfur metabolism in bacteria is unique since sulfur-containing metabolites not only constitute essential cofactors (e.g., Thiamine, SAM, Biotin etc.) to support enzymatic reactions in the cell but play essential roles in redox homeostasis, and cell signaling providing defence against antibiotic stress conditions.
The key metabolites responsible for such functions, are reactive oxidised sulfur-bound sulfur species like oxidised Thioredoxin, GSH, Cys and gas transmitter H2S. Recent reports provide evidence that establishes a direct link between such reactive sulfur metabolites with antibiotic resistance and oxidative stress relief in pathogenic bacteria.Sulfurtransferases are a group of enzymes responsible for producing these reactive sulfur metabolites from their less reactive reduced forms. 3-mercapto pyruvate sulfurtransferase (3-MST) and Thiosulfate sulfurtransferase (TST) are the two major sulfurtransferases involved in the biogenesis of many reactive sulfur metabolites.We are investigating the structure sequence relationship between different homologues of3-MST and their differences with the TSTs, majorly focusing on understanding the molecular basisfor substrate specificity (3-MP and TS); the role of the inactive domain of 3-MSTs along with theircombined physiological effects in bacteria under oxidative and antibiotic stress conditions in bothaerobic and anaerobic set up.
Contact us for more information on what’s going on in the lab.