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  • The crystal structure of the extracellular 11-heme cytochrome UndA reveals a conserved 10-heme motif and defined binding site for soluble iron chelates.

The crystal structure of the extracellular 11-heme cytochrome UndA reveals a conserved 10-heme motif and defined binding site for soluble iron chelates.

Structure (London, England : 1993) (2012-06-12)
Marcus J Edwards, Andrea Hall, Liang Shi, James K Fredrickson, John M Zachara, Julea N Butt, David J Richardson, Thomas A Clarke
ABSTRACT

Members of the genus Shewanella translocate deca- or undeca-heme cytochromes to the external cell surface thus enabling respiration using extracellular minerals and polynuclear Fe(III) chelates. The high resolution structure of the first undeca-heme outer membrane cytochrome, UndA, reveals a crossed heme chain with four potential electron ingress/egress sites arranged within four domains. Sequence and structural alignment of UndA and the deca-heme MtrF reveals the extra heme of UndA is inserted between MtrF hemes 6 and 7. The remaining UndA hemes can be superposed over the heme chain of the decaheme MtrF, suggesting that a ten heme core is conserved between outer membrane cytochromes. The UndA structure has also been crystallographically resolved in complex with substrates, an Fe(III)-nitrilotriacetate dimer or an Fe(III)-citrate trimer. The structural resolution of these UndA-Fe(III)-chelate complexes provides a rationale for previous kinetic measurements on UndA and other outer membrane cytochromes.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ferric citrate, BioReagent, suitable for cell culture
Pricing and availability is not currently available.
Sigma-Aldrich
Iron(III) citrate, technical grade
Pricing and availability is not currently available.
Supelco
Iron(III) citrate tribasic monohydrate, 18-20% Fe basis (T)
Pricing and availability is not currently available.