| Abstract Detail
Membrane Transport Wang, Ye [1], Li, Wenbin [2], Siddiqi, Yaeesh [2], Kinghorn, James R. [3], Unkles, Shiela E. [3], Glass, Anthony D.M. [2]. Nitrite transport in Aspergillus nidulans is mediated by high-affinity nitrate transporters nrtA, nrtB and by a nitrite-specific nitA transporter. A mutant strain of Aspergillus nidulans (nrtA747 nrtB110) disrupted in two genes (NrtA and NrtB) encoding the two high-affinity nitrate (NO 3-) transporters, is unable to grow on NO3-or to accumulate 13NO3- Nevertheless, this strain maintains good growth on nitrite (NO2-) as sole source of nitrogen, suggesting the activity of a third high-affinity transporter that is nitrite-specific. Measurements of net 14NO2- uptake in strain nrtA747 nrtB110 confirmed the presence of such a transport system that we name nitA. A mutant disrupted in NitA in the nrtA747 nrtB110 background exhibited very low rates of NO2- transport that showed pH dependence consistent with passive permeation of NO2- in the form of nitrous acid. Compared to nitA, nrtB and nrtA exhibited considerably higher NO2- fluxes, However, while NO3- transport by nrtA is substantially greater that by nrtB, rates of NO2-transport by nrtB exceed those due to nrtA. Further, while rates of NO3- transport by nrtA are similar to its rates of NO2- transport, rates of NO2- transport by nrtB are 7 times greater than its rates of NO3- transport. Thus it appears that nrtA is a NO3- / NO2- transporter with equivalent facility to absorb NO3-or NO2-, nrtB is preferentially a NO2- transporter with limited capacity to absorb NO3- and nitA is exclusively a NO2- transporter .
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1 - University of British Columbia, Botany Department, 6270 University Blvd, Botany Department, Vancouver, BC, V6T1Z4, Canada
2 - University of British Columbia, Botany
3 - University of St. Andrews, Biology
Keywords:
Nitrate Transporter
nitrite transporter
Aspergillus nidulans.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P10016
Abstract ID:2582 |
