Disease relevance of ECs5213

• Heme dissociation in cytochrome b562 interferes with studies of folding kinetics, so a variant of cytochrome b562 (cytochrome c-b562) with a covalent c-type linkage to the heme has been expressed in Escherichia coli [1].
• Crystallization of cytochrome b562 from Erwinia chrysanthemi [2].

High impact information on ECs5213

• Here we probe the structural importance of such a turn in an antiparallel 4-helix bundle by randomly substituting an interhelical tripeptide in cytochrome b-562 with many different amino-acid sequences [3].
• Protein engineering of cytochrome b562 for quinone binding and light-induced electron transfer [4].
• Here, we show that coexpression from plasmids of a variant of cytochrome b562 containing a CXXCH heme-binding motif with the E. coli cytochrome c maturation (Ccm) proteins results in an essentially homogeneous product that is a correctly matured c-type cytochrome [5].
• Cytochrome b562 is not cleaved by the tail-specific protease Tsp in vitro or in the periplasm of Escherichia coli but becomes a good substrate when the C-terminal sequence WVAAA is added [6].
• In addition, the titration behavior of cytochrome b562 in solution is discussed in terms of its molecular structure [7].

Chemical compound and disease context of ECs5213

• An NMR characterization of the 98Arg --> Cys variant of iron (III)-containing cytochrome b562 from Escherichia coli has been performed and the solution structure obtained [8].
• Using the same experimental approach, we have also investigated a cytochrome b562 variant containing the special CWSCK motif that binds the active-site haem of E. coli nitrite reductase NrfA [9].

Biological context of ECs5213

• For example, the correct fold is straightforwardly obtained for the four-helix bundle protein cytochrome b562, while the double EF-hand motif of calbindin D9k is hardly obtained without ambiguity [10].

Associations of ECs5213 with chemical compounds

• Previous work has shown that, in variants of cytochrome b562 containing the H102M mutation, methionine residues provide both axial ligands to the heme iron [11].
• Consistently, binding of avidin to biotinylated single-Cys replacements in loop VIII/IX or loop X/XI blocks 4B11 binding, but avidin binding to biotinylated Cys residues in other cytoplasmic loops or insertion of cytochrome b562 into cytoplasmic loop VI/VII has no significant effect [12].
• We have introduced cysteine residues into the amino acid sequence of cytochrome b562 in positions homologous to those found in the other members of the family, generating the ubiquitous heme-binding peptide (-C-X-Y-C-H-) found in virtually all c-type cytochromes [13].

Analytical, diagnostic and therapeutic context of ECs5213

• Bis-methionine ligation to heme iron in mutants of cytochrome b562. 2. Characterization by NMR of heme-ligand interactions [11].
• Circular dichroism and resonance Raman studies of cytochrome b562 from Escherichia coli [14].
• A chimeric protein consisting of lactose permease with cytochrome b562 in the middle cytoplasmic loop and six His residues at the C terminus (LacY/L6cytb562/417H6 or "red permease") was overexpressed in Escherichia coli and isolated by nickel affinity chromatography after solubilization with dodecyl-beta,d-maltopyranoside [15].
• Spectroscopic and N-terminal sequence analyses of the purified protein demonstrate that it is identical to the chromosomally expressed cytochrome b562 purified and characterized from E. coli B [Itagaki, E. & Hager, L.P. (1966) J. Biol. Chem. 241, 3687-3695] [16].

References