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NMR assignments and relaxation studies of Thiobacillus versutus ferrocytochrome c ‐550 indicate the presence of a highly mobile 13‐residues long C‐terminal tail
Author(s) -
Ubbink Marcellus,
Pfuhl Mark,
Oost John Van Der,
Berg Axel,
Canters Gerard W.
Publication year - 1996
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560051212
Subject(s) - paracoccus denitrificans , cytochrome c , cytochrome , chemistry , stereochemistry , submitochondrial particle , crystallography , biochemistry , mitochondrion , enzyme
Cytochrome c ‐550 of Thiobacillus versutus functions as an electron transfer protein in a chain of redox proteins that enables T. versutus to grow on methylamine. It is a single‐heme protein of 134 residues, related to mitochondrial cytochrome c . Cytochrome c ‐550, as well as several other bacterial c 2 ‐type cytochromes, contain a C‐terminal extension of 13–16 amino acids of unknown function, compared to mitochondrial cytochrome c . NMR experiments were performed to obtain structural and dynamic information on the protein in solution. For this purpose, T. versutus cytochrome c ‐550 was labeled with 15 N and 13 C using 13 C‐methanol grown Paracoccus denitrificans as a host for heterologous expression. NMR assignments were obtained for the 1 H, 15 N, and 13 C nuclei in the backbone and the β‐positions of the protein and the secondary structure was determined. 15 N‐relaxation studies were performed to characterize the dynamic properties of the protein. The results indicate that the main part of T. versutus ferrocytochrome c ‐550 exists in solution as a rigid, well‐ordered molecule with a secondary structure that is very similar to that of P. denitrificans cytochrome c‐550, as observed in crystals. The C‐terminal extension, however, is unstructured and highly mobile. The possible origin and function of the extension are discussed.