3KH7

Crystal structure of the periplasmic soluble domain of reduced CcmG from Pseudomonas aeruginosa

Summary for 3KH7

• Entry DOI: 10.2210/pdb3kh7/pdb
• Related: 3KH9
• Descriptor: Thiol:disulfide interchange protein dsbE (2 entities in total)
• Functional Keywords: trx-like, thiol-disulfide exchange, cell inner membrane, cytochrome c-type biogenesis, disulfide bond, redox-active center, transmembrane, oxidoreductase
• Biological source: Pseudomonas aeruginosa
• Cellular location: Cell inner membrane ; Single- pass membrane protein ; Periplasmic side : Q9I3N1
• Total number of polymer chains: 1
• Total formula weight: 19560.18

Authors

Di Matteo, A.,Calosci, N.,Gianni, S.,Jemth, P.,Brunori, M.,Travaglini Allocatelli, C. (deposition date: 2009-10-30, release date: 2010-04-07, Last modification date: 2023-09-06)

Primary citation

Di Matteo, A.,Calosci, N.,Gianni, S.,Jemth, P.,Brunori, M.,Travaglini-Allocatelli, C.
Structural and functional characterization of CcmG from Pseudomonas aeruginosa, a key component of the bacterial cytochrome c maturation apparatus.
Proteins, 78:2213-2221, 2010

PubMed Abstract: The cytochrome c maturation process is carried out in the bacterial periplasm, where some specialized thiol-disulfide oxidoreductases work in close synergy for the correct reduction of oxidized apocytochrome before covalent heme attachment. We present a structural and functional characterization of the soluble periplasmic domain of CcmG from the opportunistic pathogen P. aeruginosa (Pa-CcmG), a component of the protein machinery involved in cyt c maturation in gram-negative bacteria. X-ray crystallography reveals that Pa-CcmG is a TRX-like protein; high-resolution crystal structures show that the oxidized and the reduced forms of the enzyme are identical except for the active-site disulfide. The standard redox potential was calculated to be E(0') = -0.213 V at pH 7.0; the pK(a) of the active site thiols were pK(a) = 6.13 +/- 0.05 for the N-terminal Cys74 and pK(a) = 10.5 +/- 0.17 for the C-terminal Cys77. Experiments were carried out to characterize and isolate the mixed disulfide complex between Pa-CcmG and Pa-CcmH (the other redox active component of System I in P. aeruginosa). Our data indicate that the target disulfide of this TRX-like protein is not the intramolecular disulfide of oxidized Pa-CcmH, but the intermolecular disulfide formed between Cys28 of Pa-CcmH and DTNB used for the in vitro experiments. This observation suggests that, in vivo, the physiological substrate of Pa-CcmG may be the mixed-disulfide complex between Pa-CcmH and apo-cyt.

PubMed: 20544959
DOI: 10.1002/prot.22733

Experimental method

X-RAY DIFFRACTION (1.75 Å)