Programma: PRIN
Responsabile scientifico per il dipartimento: Emanuele Paci
Struttura principale: DIFA
Data inizio e data fine: dal 05/10/2023 al 05/10/2025
TonB: forza meccanica e nuove strategie antibatteriche
Il progetto studia il meccanismo del TonB, proteina batterica che genera forza meccanica per importare nutrienti, con implicazioni per nuove terapie contro batteri Gram-negativi resistenti.
TonB: Mechanical Force and New Antibacterial Strategies
The project investigates TonB, a bacterial protein generating mechanical force to import nutrients, with implications for novel therapies against resistant Gram-negative bacteria.
Abstract
The proposal aims to investigate the function of an important bacterial protein of which alarge fraction is unstructured and able to produce a mechanical force in the presence of aspecific environmental signal. The capture and import of scarce nutrients in Gram negativebacteria are carried out by a range of homologous outer membrane proteins. To allow cargotransit into the periplasm, a plug domain that occludes the lumen of each of these must beactively pulled out. It is now evident that the work is provided by a single protein residentin the inner membrane, called TonB, but its working mechanism remains elusive.Preliminary data show that the intrinsically disordered linker domain of TonB, hithertothought to play a passive role in the process, can switch from compact and mechanicallystable to expanded and force labile structures upon changes in ionic strength, potentiallydriving the remodelling (i.e., the unplugging) of the outer membrane transporter. The aimof this proposal is to understand the physical basis of this remodeling, uncovering a novelfunction of intrinsically disordered proteins that impart mechanical signals by “functionalcollapse”.The proposal is grounded on a wealth of preliminary data and aims to directly observe andmeasure the force exerted by the TonB protein at single molecule level using opticaltweezers. Physical models and novel approaches to molecular simulation will be key tointerpret experimental results, and predict modifications to the sequence of the protein thatwould affect the ability of bacteria to feed themselves. While the research carried out isfundamental in nature, our findings will provide information that can be directly used todevise alternatives to current anti-bacterial treatments, much needed given the steadilyincreasing antibiotics resistance. Also relevant for the development of novel antibacterialstrategies is the fact that the nutrient import mechanism of Gram-negative bacteria, thecentral topic of this proposal, is hijacked by bacteriocins, killer proteins produced bycompeting bacteria.