The transport and intracellular distribution of iron in Ustilago sphaerogena via the native siderochrome ferrichrome A has been examined. Evidence is presented which suggests the involvement of deferriferrichrome in iron transport when the metal is supplied to the cell as ferrichrome A. This process requires both oxygen and ATP synthesis and may require a transmembrane electrochemical gradient. Once inside the cell, iron derived from ferrichrome A is rapidly distributed, with a major fraction found in the mitochondria, presumably as heme.
The kinetics of ferrichrome and ferrichrome A uptake have also been investigated. The Km of transport of ferrichrome was determined to be 0.6 μM with a maximum velocity of 1.55 nmoles/min/mg. For ferrichrome A the Km was found to be 7.6 μM; Vmax was 0.85 nmoles/ min/mg. Ferrichrome functions as a competitive inhibitor of ferrichrome A transport with a Ki of 14 μM, while ferrichrome A inhibited ferrichrome transport in a noncompetitive manner. Together these data are consistent with a two-site model for siderochrome transport. A model for the transport process is presented.
The exchange of iron from fcA to deferrifch has also been examined. The ratio of the binding constants between fcA and fch was found to be 5.29. From this data the binding constant for fcA was determined to be 6.82x10^29.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-8299 |
| Date | 01 May 1981 |
| Creators | Passavant, Charles W. |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
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