Architecture of the Heme-translocating CcmABCD/E complex required for Cytochrome c maturation.

Mono- and multiheme cytochromes c are post-translationally matured by the covalent attachment of heme. For this, Escherichia coli employs the most complex type of maturation machineries, the Ccm-system (for cytochrome c maturation). It consists of two membrane protein complexes, one of which shuttles heme across the membrane to a mobile chaperone that then delivers the cofactor to the second complex, an apoprotein:heme lyase, for covalent attachment.

Architecture of the membrane-bound cytochrome c heme lyase CcmF.

The covalent attachment of one or multiple heme cofactors to cytochrome c protein chains enables cytochrome c proteins to be used in electron transfer and redox catalysis in extracytoplasmic environments. A dedicated heme maturation machinery, whose core component is a heme lyase, scans nascent peptides after Sec-dependent translocation for CXCH-binding motifs. Here we report the three-dimensional (3D) structure of the heme lyase CcmF, a 643-amino acid integral membrane protein, from Thermus thermophilus.

Structural and Functional Analysis of Latex Clearing Protein (Lcp) Provides Insight into the Enzymatic Cleavage of Rubber.

Latex clearing proteins (Lcps) are rubber oxygenases that catalyse the extracellular cleavage of poly (cis-1,4-isoprene) by Gram-positive rubber degrading bacteria. Lcp of Streptomyces sp. K30 (Lcp) is a b-type cytochrome and acts as an endo-type dioxygenase producing C and higher oligo-isoprenoids that differ in the number of isoprene units but have the same terminal functions, CHO-CH- and -CH-COCH.