Revision as of 13:50, 28 September 2024

nasE Homodimeric Transmembrane Protein

nasE composes the membrane spanning subunit of the ABC nitrate transporter protein from the ANRA pathway, responsible for allowing the selective passage of nitrate ions through the membrane while maintaing the cell’s electrochemical gradient (Lin & Stewart, 1997).

Usage and Biology

Nitrate assimilation in bacteria occurs through 3 main steps: (1) Nitrate uptake from the extracellular space by a trasporter, (2) Conversion of nitrate to nitrite by the nitrate reductase enzyme and (3) Reduction to ammonium of the nitrite by nitrite reductase.

The transporter protein is a crucial part in the ANRA pathway. It’s an ATP-binding casette (ABC) transporter enzyme. To be able to transport the nitrate ions through the membrane, this group of transporters require energy from ATP hydroloysis. This transporter is composed of of three subunits: a periplasmic protein that binds NO3-, a transmembrane protein, and a cytoplasmic ATPase attached to the membrane (Lin & Stewart, 1997; Moreno-Vivián & Flores, 2007). Its high-affinity binding of NO3- enables efficient uptake even at low external concentrations.

The nasFED nitrate transporter complex (Wu & Stewart, 1998)

Considerations

To ensure a proper functionality of the transporter enzyme, the sequence encoding nasE should be introduced with the other 2 subunits nasF(BBa_5306000) and nas D (BBa_5306002) as these genes has been found by Wu & Stewart (1998) to work as an operon. If you want to introduce the whole nitrate assimilation pathway as our team did, you can find the whole operon sequence that contains all the coding sequences that you need in our composite part’s page (BBa_K5306006) or access each one individually from this list:

• nasF (BBa_5306000)
• nasE (This Part)
• nasD (BBa_5306002)
• nasC (BBa_5306003)
• nasB (BBa_5306004)
• nasA (BBa_5306005)

Sequence and Features