| Autor: |
Anderson, Lisa A., Palmer, Tracy, Price, Nicholas C., Bornemann, Stephen, Boxer, David H., Pau, Richard N. |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; 5/15/97, Vol. 246 Issue 1, p119-126, 8p |
| Abstrakt: |
Molybdenum-dependent repression of trancription of the Escherichia coli modABNCD operon. which encodes the high-affinity molybdate transporter,is mediated by the ModE protein. this regulatory protein was purified as an N-terminal His-tagged derivative and characterised and both with and without the N-terminal oligohistidine extension.Equilibrium centrifugation showed that ModE is at least a 51-KDa homodimer,Circular dichroism spectroscopy incadicate that when molybdate or tungstate bind to ModE there is little change in its a-helical content, but a major change in the environment of tryphan and tryosine reesidues occurs. Addition of Molybdate or tungstate to the protiten results in almost 50% quenching of the fluorescence attributed to trytophan.Titration of fluorescence quenching showed that two molecules of molybdenum bind to each dimer of ModE with a Kd of 0.8 ´a;M.DNA mobility-shift assays showed that ModE requires molbdenum region. In accored with affinity (approximate Kd of 30nM ModE) to the modABC promoter region, In accord with ModE's role as a molydenum-dependent transcriptional repressor.DNase footprinting experimenting experiments shwed that the ModE-molybdenum complex contains a songle 31-bp region around the transcription start modABCD prometer.This region contains a 6-base palindromic sequence CGTTAT-N12>-ATAACG. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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