Diversity of transport mechanisms: common structural principles

Deletion of the yiaMNO transporter genes affects the growth characteristics of Escherichia coli K-12

“…Prokaryotes employ several classes of transport systems for the uptake of solutes from their environment, which are defined on the basis of their subunit composition and mode of energization (Driessen et al, 2000). The recently discovered binding-protein-dependent secondary (Driessen et al, 1997(Driessen et al, , 2000, or tripartite ATP-independent periplasmic (TRAP) (Forward et al, 1997;Rabus et al, 1999;Kelly & Thomas, 2001) transporters utilize a solute-binding protein that captures the substrate at the outside of the cell and deliver it to a membrane permease that is made up of two subunits.…”

“…The recently discovered binding-protein-dependent secondary (Driessen et al, 1997(Driessen et al, , 2000, or tripartite ATP-independent periplasmic (TRAP) (Forward et al, 1997;Rabus et al, 1999;Kelly & Thomas, 2001) transporters utilize a solute-binding protein that captures the substrate at the outside of the cell and deliver it to a membrane permease that is made up of two subunits. The large subunit contains 12 putative transmembrane domains (TMDs) and a large cytoplasmic loop between TMD 6 and TMD 7, and thus resembles classical secondary transporters.…”

“…The small subunit is made up of four putative TMDs. Transport is driven by the proton-motive force (pmf), in contrast to the more familiar binding-proteindependent ATP-binding cassette (ABC) transporters that are energized by ATP hydrolysis (Driessen et al, 1997(Driessen et al, , 2000Forward et al, 1997;Rabus et al, 1999;Kelly & Thomas, 2001;Wyborn et al, 2001). …”

4-Chlorobenzoate Uptake in Comamonas sp. Strain DJ-12 Is Mediated by a Tripartite ATP-Independent Periplasmic Transporter

“…Transport of 4-chlorobenzoate shows significant inhibition by 4-bromo-, 4-iodo-, and 4-fluorobenzoate and mild inhibition by 3-chlorobenzoate, 2-chlorobenzoate, 4-hydroxybenzoate, 3-hydroxybenzoate, and benzoate. Uptake of 4-chlorobenzoate is significantly inhibited by ionophores which collapse the proton motive force.Bacterial transport systems have traditionally been divided into four general classes based on energy coupling mechanisms, primary sequence, and mode of transport (7,16,25,28). Primary and secondary transporters facilitate solute transport into the cell coupled with a source of energy (i.e., a chemical reaction, light absorption, or electron flow) or an ion electrochemical gradient, respectively (28).…”

“…Bacterial transport systems have traditionally been divided into four general classes based on energy coupling mechanisms, primary sequence, and mode of transport (7,16,25,28). Primary and secondary transporters facilitate solute transport into the cell coupled with a source of energy (i.e., a chemical reaction, light absorption, or electron flow) or an ion electrochemical gradient, respectively (28).…”