Difference between revisions of "Part:BBa K1675001"

Latest revision as of 21:32, 18 September 2015

NhaB; sodium-proton antiporter; membrane protein

The gene, NhaB, is the archetypal sodium/proton anti-porter in E. coli. It is crucial when NhaA’s activity is limited, such as NhaA is not sufficiently induced, or NhaA is not activated.

NhaB catalyzes the exchange of 3 protons per 2 sodiums.(Fig.2) NhaB has a high affinity for sodium and lithium. Its activity is weakly pH-dependent, which is essential for regulation of intracellular pH under alkaline conditions. Therefore, NhaB could make sure E. coli’s survival under alkaline pH, which are in desperate need of our project.

Fig.1 The mechanism of NhaB

Sequence and Features

Assembly Compatibility:

10
COMPATIBLE WITH RFC[10]
12
COMPATIBLE WITH RFC[12]
21
INCOMPATIBLE WITH RFC[21]
Illegal BglII site found at 5
23
COMPATIBLE WITH RFC[23]
25
INCOMPATIBLE WITH RFC[25]
Illegal AgeI site found at 1003
Illegal AgeI site found at 1315
1000
COMPATIBLE WITH RFC[1000]

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 <partinfo>BBa_K1675001 short</partinfo>
-The gene, ''NhaB'', is the archetypal sodium/proton anti-porter in ''E. coli''. It is crucial when the level of ''NhaA'' activity is growth limiting, when ''NhaA'' is not sufficiently induced, and/or when ''NhaA'' is not activated.
+The gene, ''NhaB'', is the archetypal sodium/proton anti-porter in ''E. coli''. It is crucial when ''NhaA''’s activity is limited, such as ''NhaA'' is not sufficiently induced, or ''NhaA'' is not activated.
-''NhaA'' catalyzes the exchange of 3 protons per 2 sodium ions. Therefore, ''NhaA'' could make sure ''E. coli''’s survival under alkaline pH, which are in desperate need in our project.
+''NhaB'' catalyzes the exchange of 3 protons per 2 sodiums.(Fig.2) ''NhaB'' has a high affinity for sodium and lithium. Its activity is weakly pH-dependent, which is essential for regulation of intracellular pH under alkaline conditions. Therefore, ''NhaB'' could make sure ''E. coli''’s survival under alkaline pH, which are in desperate need of our project.
+[[File:BIT_China_Resistance_System_pic2.png]]
+Fig.1 The mechanism of ''NhaB''
 <!-- Add more about the biology of this part here
 ===Usage and Biology===
+In the absence of ''NhaA'', ''NhaB'' confers a certain tolerance to sodium which decreases with increasing pH. Essential for regulation of intracellular pH under alkaline conditions, ''NhaB'' is crucial when the level of ''NhaA'' activity is limiting, when ''NhaA'' is not sufficiently induced, and/or when ''NhaA'' is not activated. Unlike ''NhaA'', the activity of ''NhaB'' shows no dependence on pH in the range 6.4-8.3. The affinity of ''NhaB'' to sodium (Km = 40-70μM) is higher than that of ''NhaA''.
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