Significance of α‐subunit VISITDG sequence residues in the catalytic sites of Escherichia coli ATP synthase (LB247)

Abstract

Background: F1Fo ATP synthase is the fundamental means of cellular energy production in animals, plants, and almost all microorganisms. ATP is generated by oxidative or photophosphorylation in membranes of bacteria, mitochondria, and chloroplasts. A typical 70 kg human with a relatively sedentary lifestyle will generate around 2.0 million kg of ATP from ADP and Pi (inorganic phosphate) in a 75‐year lifespan. ATP synthase is the smallest known biological nanomotor, found from bacteria to man. Being the smallest biological nanomotor, ATP synthase is in the forefront of nanomedicine. Nanomedicine results from nanotechnology where molecular scale nanomotors can be used to treat disease conditions. The question of paramount importance is how to build nanomachines that are compatible with living systems and can safely operate inside the body. Here we propose that ATP synthase is a workable base model for the development of nanomotors in nanomedicine usage. In order to use it as base model we must elucidate its catalytic properties. Phosphate (Pi) binding is a primary step in ATP synthesis, so understanding the molecular basis of Pi binding is an important goal. Methods: Mutagenic analysis of the catalytic site highly conserved α‐subunit VISIT‐DG sequence residues were performed to generates single and double mutants. Growth patterns were observed on limiting glucose and succinate plates. MgPi protection assay against NBD‐Cl induced inhibition was performed to reveal the direct or indirect role of residues in Pi binding. Results: Lately, we found that αSer‐347 of the VISIT‐DG sequence is the fifth important residue involved in phosphate binding as are the four catalytic site residues βLys‐155, βArg‐182, αArg‐376, and βArg‐246. Currently we are exploring the role of other VISIT‐DG sequence residues particularly αThr‐349 and αAsp‐350 in Pi binding.Grant Funding Source: supported by NIH/GM085771