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Study of factors influencing the function of MntH, membrane transport protein of E. coli
Jurková, Ingrid ; Urbánková, Eva (advisor) ; Krůšek, Jan (referee)
MntH belongs to the Nramp family of transport proteins, and plays an important role not only in homeostasis of iron and manganese, but also in bacterial defence against the immunity response of an infected host cell. MntH co-transports divalent metal ions into the cell together with protons with a stoichiometry dependent on the membrane potential and extracellular pH. Using the redistribution potential dye diS-C3(3), we measured the effects of MNTH expression and MntH-mediated metal transport on the cell membrane potential and intracellular pH. Cells expressing MNTH were found to be hyperpolarised and their membrane potential was depolarised upon the addition of metal ions. In the theoretical part of our work, we explored general four-, six-, and eight-state carrier models that were modified by introducing the voltage dependence of all rate constants. Using mathematical modelling, we simulated the effect of various model parameters (including membrane potential, substrate concentration, and carrier or substrate charge) on substrate influx. We observed some of the transport characteristics described for MntH proteins such as variable symport stoichiometry that is influenced by the membrane potential and pH. However, for a more detailed simulation of the eight-state carrier model, more information about...
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