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Biology subjects

Anastas, A.

Publications and source records attributed to Anastas, A..

2 recordsLinked to original sources

An effective method of measuring nanobody binding kinetics and competition-based epitope mapping using biolayer interferometry

Protein-protein interactions (PPI) underpin nearly all biological processes, and understanding the molecular mechanisms governing these interactions is crucial for the progress of biomedical sciences. The emergence of AI-driven computational tools can help reshape the methods in structural biology, however model data often quires empirical validation. The large scale of predictive modeling data will therefore benefit from optimized methodologies for the high-throughput biochemical characterization of PPIs. Biolayer interferometry (BLI) is one of very few approaches that can determine the rate of biomolecular interactions, called kinetics, and of the commonly available kinetic measurement techniques, it is the most suitable for high-throughput experimental designs. Here, we provide step-by-step instructions on how to perform kinetics experiments using BLI. We further describe the basis and execution of competition and epitope binning experiments, which are particularly useful for antibody and nanobody screening applications. The procedure requires 3 hours to complete and is suitable for users with minimal experience with biochemical techniques.

biochemistry↗

ESAT-6 undergoes self-association at phagosomal pH and an ESAT-6 specific nanobody restricts M. tuberculosis growth in macrophages

Mycobacterium tuberculosis (Mtb) is known to survive within macrophages by compromising the integrity of the phagosomal compartment in which it resides. This activity primarily relies on the ESX-1 secretion system, predominantly involving the protein duo ESAT-6 and CFP-10. CFP-10 likely acts as a chaperone, while ESAT-6 likely disrupts phagosomal membrane stability via a largely unknown mechanism. we employ a series of biochemical analyses, protein modeling techniques, and a novel ESAT-6-specific nanobody to gain insight into the ESAT-6s mode of action. First, we measure the binding kinetics of the tight 1:1 complex formed by ESAT-6 and CFP-10 at neutral pH. Subsequently, we demonstrate a rapid self-association of ESAT-6 into large complexes under acidic conditions, leading to the identification of a stable tetrameric ESAT-6 species. Using molecular dynamics simulations, we pinpoint the most probable interaction interface. Furthermore, we show that cytoplasmic expression of an anti-ESAT-6 nanobody blocks Mtb replication, thereby underlining the pivotal role of ESAT-6 in intracellular survival. Together, these data suggest that ESAT-6 acts by a pH dependent mechanism to establish two-way communication between the cytoplasm and the Mtb-containing phagosome.

biochemistry↗