OmpF together with OmpC are the main bacterial outer-membrane porins expressed by Enterobacteriaceae. They can filter small polar molecules thanks to an hour-glass shape and internal charge segregation that eventually create a transversal electric field. They are considered the main pathway for the entry of small polar antibiotics and since the determination of their high-resolution structure they have been used as model for general bacterial porins. The expression of either OmpF or OmpC is regulated by different factors with a preference of OmpC at high osmolarity.<br/>We combined MD simulations and electrophysiology measurements at single-channel single-molecule level, to investigate the role of temperature on transport. We investigated both OmpF and OmpC and some selected mutant. We measured the association rate of small molecules as function of temperature, showing two regimes for OmpF. MD simulations were able to describe the transition induced by temperature as a conformational change of the constricting loop L3 followed by trapping of a potassium ion. As revealed by mutants, the combination of the two effects is sequence-dependent and it is not present in OmpC. The latter can be considered a more robust channel being insensitive to several external parameters, such as ion concentration and temperature.<br/>

Temperature sensor in bacterial porins

256th National Meeting (2018)

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