The interaction of covalently bound heme with the cytochrome c maturation protein CcmE.
The heme chaperone CcmE is a novel protein that binds heme covalently via a histidine residue as part of its essential function in the process of cytochrome c biogenesis in many bacteria as well as plant mitochondria. In the continued absence of a structure of the holoform of CcmE, identification of the heme ligands is an important step in understanding the molecular function of this protein and the role of covalent heme binding to CcmE during the maturation of c-type cytochromes. In this work, we present spectroscopic data that provide insight into the ligation of the heme iron in the soluble domain of CcmE from Escherichia coli. Resonance Raman spectra demonstrated that one of the heme axial ligands is a histidine residue and that the other is likely to be Tyr134. In addition, the properties of the heme resonances of the holo-protein as compared with those of a form of CcmE with non-covalently bound heme provide evidence for the modification of one of the heme vinyl side chains by the protein, most likely the 2-vinyl group.
Uchida
Takeshi
T
Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan.
Stevens
Julie M
JM
Daltrop
Oliver
O
Harvat
Edgar M
EM
Hong
Lin
L
Ferguson
Stuart J
SJ
Kitagawa
Teizo
T
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006418:Heme / Q000737:chemistry* / Q000378:metabolism*; D006420:Hemeproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry; D008024:Ligands; D011485:Protein Binding; D013059:Spectrum Analysis, Raman; D014443:Tyrosine / Q000737:chemistry
D001425:Bacterial Outer Membrane Proteins; C115384:CcmE protein, E coli; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006420:Hemeproteins; D008024:Ligands; D014443:Tyrosine; D006418:Heme; D006639:Histidine; D045304:Cytochromes c