Anno2009
AutoriDe Angeli A, Moran O, Wege S, Filleur S, Ephritikhine G, Thomine S, Barbier-Brygoo H, Gambale F
AbstractNitrate, one of the major nitrogen sources for plants, is stored in the vacuole. Nitrate accumulation within the vacuole is primarily mediated by the NO(3)(-)/H(+) exchanger AtCLCa, which belongs to the chloride channel (CLC) family. Crystallography analysis of hCLC5 suggested that the C-terminal domain, composed by two cystathionine beta-synthetase motifs in all eukaryotic members of the CLC family is able to interact with ATP. However, interaction of nucleotides with a functional CLC protein has not been unambiguously demonstrated. Here we show that ATP reversibly inhibits AtCLCa by interacting with the C-terminal domain. Applying the patch clamp technique to isolated Arabidopsis thaliana vacuoles, we demonstrate that ATP reduces AtCLCa activity with a maximum inhibition of 60%. ATP inhibition of nitrate influx into the vacuole at cytosolic physiological nitrate concentrations suggests that ATP modulation is physiologically relevant. ADP and AMP do not decrease the AtCLCa transport activity; nonetheless, AMP (but not ADP) competes with ATP, preventing inhibition. A molecular model of the C terminus of AtCLCa was built by homology to hCLC5 C terminus. The model predicted the effects of mutations of the ATP binding site on the interaction energy between ATP and AtCLCa that were further confirmed by functional expression of site-directed mutated AtCLCa.
RivistaJournal Of Biological Chemistry
ISSN0021-9258
Impact factor5.328
Volume284
Pagina inizio26526
Pagina fine26532
Autori IBFFranco GAMBALE, Oscar MORAN
Linee di Ricerca IBFMD.P01.001.001, MD.P01.009.001
Sedi IBFIBF.GE