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Helix swapping leads to dimerization of the N‐terminal domain of the c ‐type cytochrome maturation protein CcmH from Escherichia coli
Author(s) -
Ahuja Umesh,
Rozhkova Anna,
Glockshuber Rudolf,
Thöny-Meyer Linda,
Einsle Oliver
Publication year - 2008
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2008.07.007
Subject(s) - terminal (telecommunication) , escherichia coli , chemistry , escherichia coli proteins , domain (mathematical analysis) , helix (gastropod) , c terminus , cytochrome , cytochrome c , stereochemistry , biology , biochemistry , gene , amino acid , computer science , mitochondrion , enzyme , telecommunications , mathematical analysis , ecology , mathematics , snail
In the process of cytochrome c maturation, heme groups are covalently attached to reduced cysteines of specific heme‐binding motifs (CXXCH) in an apocytochrome c sequence. In Escherichia coli , the CcmH protein maintains apo‐protein cysteines in a reduced state prior to heme attachment. We have purified and biophysically, as well as structurally characterized the soluble, N‐terminal domain of E. coli CcmH that carries the functionally relevant LRCXXC‐motif. In contrast to a recently presented structure of the homologous domain from Pseudomonas aeruginosa , the E. coli protein forms a tightly interlinked dimer by swapping its N‐terminal helix between two monomers. We propose that an altered environment of the functional motif may help to discern between the two redox partners CcmG and apocytochrome c .