abstract
The mechanism of bacterial resistance to tributyltin (TBT) is still unclear. The results herein presented contribute to clarify that mechanism in the TBT-resistant bacterium Aeromonas molluscorum Av27. We have identified and cloned a new gene that is involved in TBT resistance in this strain. The gene is highly homologous (84%) to the Aeromonas hydrophila-sugE gene belonging to the small multidrug resistance gene family (SMR), which includes genes involved in the transport of lipophilic drugs. In Av27, expression of the Av27-sugE was observed at the early logarithmic growth phase in the presence of a high TBT concentration (500 mu M), thus suggesting the contribution of this gene for TBT resistance. E. coli cells transformed with Av27-sugE become resistant to ethidium bromide (EtBr), chloramphenicol (CP) and tetracycline (TE), besides TBT. According to the Moriguchi logP (miLogP) values, EtBr, CP and TE have similar properties and are substrates for the sugE-efflux system. Despite the different miLogP of TBT, E. coli cells transformed with Av27-sugE become resistant to this compound. So it seems that TBT is also a substrate for the SugE protein. The modelling studies performed also support this hypothesis. The data herein presented clearly indicate that sugE is involved in TBT resistance of this bacterium.
keywords
MULTIDRUG TRANSPORTER EMRE; ESCHERICHIA-COLI; EFFLUX PUMP; MARINE-BACTERIA; PROTEINS; EXPRESSION; CHLORIDE; PORTUGAL; AVEIRO; FAMILY
subject category
Biotechnology & Applied Microbiology; Microbiology
authors
Cruz, A; Micaelo, N; Felix, V; Song, JY; Kitamura, SI; Suzuki, S; Mendo, S
our authors
Vítor Félix
Associate Professor with Aggregationacknowledgements
This work was supported by the project FCOMP-01-0124-FEDER-010630, Fundacao para a Ciencia e Tecnologia-FCT, Portugal, COMPETE Program, co-funded by FEDER. Andreia Cruz was supported by the grants SFRH/BD/36047/2007 from FCT (Portugal) and JSPS Grant-in-Aid (19380184) from the Global-COE Program of Ehime University (Japan).