Difference between revisions of "Part:BBa K1675000"

Revision as of 20:41, 18 September 2015

NhaA; sodion-proton antiporter; membrane protein

Nha is a family containing a number of bacterial sodium-proton anti-porters. These are integral membrane proteins that catalyze the exchange of protons for sodiums in a manner highly dependent on the pH. To resist different pH, we selected two genes, NhaA and NhaB, from this family.

NhaA is the archetypal sodium/proton anti-porter and the only member of the family that is required by E.coli for survival under alkaline stress. It is a membrane protein consisting of 388 residues. NhaA excretes sodiums from the cytoplasm using the energy from the cotransport of protons down their electrochemical gradient into the cell, with a characteristic electrogenic stoichiometry of two protons to one sodium (Fig.1). Like many other sodium/proton anti-porters, NhaA is regulated by pH. It is essentially inactive below pH 7, and the sodium efflux rate increases by three orders of magnitude between pH 6.5 and 8.5.

Fig.1 The mechanism of ''NhaA''

We cloned the gene NhaA from the genome of Escherichia coli str. K-12. The agarose gel electrophoresis analysis of NhaA is shown in Fig.2.

File:BIT China the positive clones of NhaA.png

Fig.2 The positive clones of ''NhaA''

Sequence and Features