A cytosolic trans-activation domain essential for ammonium uptake.
In: Nature, Jg. 446 (2007-03-08), Heft 7132, S. 195-198
Online
academicJournal
Zugriff:
Polytopic membrane proteins are essential for cellular uptake and release of nutrients. To prevent toxic accumulation, rapid shut-off mechanisms are required. Here we show that the soluble cytosolic carboxy terminus of an oligomeric ammonium transporter from Arabidopsis thaliana serves as an allosteric regulator essential for function; mutations in the C-terminal domain, conserved between bacteria, fungi and plants, led to loss of transport activity. When co-expressed with intact transporters, mutants inactivated functional subunits, but left their stability unaffected. Co-expression of two inactive transporters, one with a defective pore, the other with an ablated C terminus, reconstituted activity. The crystal structure of an Archaeoglobus fulgidus ammonium transporter (AMT) suggests that the C terminus interacts physically with cytosolic loops of the neighbouring subunit. Phosphorylation of conserved sites in the C terminus are proposed as the cognate control mechanism. Conformational coupling between monomers provides a mechanism for tight regulation, for increasing the dynamic range of sensing and memorizing prior events, and may be a general mechanism for transporter regulation. [ABSTRACT FROM AUTHOR]
Titel: |
A cytosolic trans-activation domain essential for ammonium uptake.
|
---|---|
Autor/in / Beteiligte Person: | Loqué, D. ; Lalonde, S. ; Looger, L. L. ; von Wirén, N. ; Frommer, W. B. |
Link: | |
Zeitschrift: | Nature, Jg. 446 (2007-03-08), Heft 7132, S. 195-198 |
Veröffentlichung: | 2007 |
Medientyp: | academicJournal |
ISSN: | 0028-0836 (print) |
DOI: | 10.1038/nature05579 |
Schlagwort: |
|
Sonstiges: |
|