3OUE

Structure of C-terminal hexaheme fragment of GSU1996

Summary for 3OUE

• Entry DOI: 10.2210/pdb3oue/pdb
• Related: 1hh5 1rwj 3OUQ 3OV0 3bxu 3h33 3h34 3h4n
• Descriptor: Cytochrome c family protein, SULFATE ION, HEME C, ... (4 entities in total)
• Functional Keywords: multiheme cytochrome-c, electron transfer, fe reduction, geobacter sulfurreducens, cytochrome c7 (c3) fold, electron transport
• Biological source: Geobacter sulfurreducens
• Total number of polymer chains: 1
• Total formula weight: 21192.20

Authors

Pokkuluri, P.R.,Schiffer, M. (deposition date: 2010-09-14, release date: 2010-12-29, Last modification date: 2024-10-30)

Primary citation

Pokkuluri, P.R.,Londer, Y.Y.,Duke, N.E.,Pessanha, M.,Yang, X.,Orshonsky, V.,Orshonsky, L.,Erickson, J.,Zagyanskiy, Y.,Salgueiro, C.A.,Schiffer, M.
Structure of a novel dodecaheme cytochrome c from Geobacter sulfurreducens reveals an extended 12nm protein with interacting hemes.
J.Struct.Biol., 174:223-233, 2011

PubMed Abstract: Multiheme cytochromes c are important in electron transfer pathways in reduction of both soluble and insoluble Fe(III) by Geobacter sulfurreducens. We determined the crystal structure at 3.2Å resolution of the first dodecaheme cytochrome c (GSU1996) along with its N-terminal and C-terminal hexaheme fragments at 2.6 and 2.15Å resolution, respectively. The macroscopic reduction potentials of the full-length protein and its fragments were measured. The sequence of GSU1996 can be divided into four c(7)-type domains (A, B, C and D) with homology to triheme cytochromes c(7). In cytochromes c(7) all three hemes are bis-His coordinated, whereas in c(7)-type domains the last heme is His-Met coordinated. The full-length GSU1996 has a 12nm long crescent shaped structure with the 12 hemes arranged along a polypeptide to form a "nanowire" of hemes; it has a modular structure. Surprisingly, while the C-terminal half of the protein consists of two separate c(7)-type domains (C and D) connected by a small linker, the N-terminal half of the protein has two c(7)-type domains (A and B) that form one structural unit. This is also observed in the AB fragment. There is an unexpected interaction between the hemes at the interface of domains A and B, which form a heme-pair with nearly parallel stacking of their porphyrin rings. The hemes adjacent to each other throughout the protein are within van der Waals distance which enables efficient electron exchange between them. For the first time, the structural details of c(7)-type domains from one multiheme protein were compared.

PubMed: 21130881
DOI: 10.1016/j.jsb.2010.11.022

Experimental method

X-RAY DIFFRACTION (2.15 Å)