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Haem‐delivery proteins in cytochrome c maturation System II
Author(s) -
Ahuja Umesh,
Kjelgaard Peter,
Schulz Benjamin L.,
ThönyMeyer Linda,
Hederstedt Lars
Publication year - 2009
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2009.06833.x
Subject(s) - biology , bacillus subtilis , cytochrome , bacterial outer membrane , biochemistry , escherichia coli , cytoplasm , cytochrome c , heme , membrane protein , bacteria , membrane , gene , mitochondrion , genetics , enzyme
Summary Cytochromes of the c ‐type function on the outer side of the cytoplasmic membrane in bacteria where they also are assembled from apo‐cytochrome polypeptide and haem. Two distinctly different systems for cytochrome c maturation are found in bacteria. System I present in Escherichia coli has eight to nine different Ccm proteins. System II is found in Bacillus subtilis and comprises four proteins: CcdA, ResA, ResB and ResC. ResB and ResC are poorly understood polytopic membrane proteins required for cytochrome c synthesis. We have analysed these two B. subtilis proteins produced in E. coli and in the native organism. ResB is shown to bind protohaem IX and haem is found covalently bound to residue Cys‐138. Results in B. subtilis suggest that also ResC can bind haem. Our results complement recent findings made with Helicobacte r CcsBA supporting the hypothesis that ResBC as a complex translocates haem by attaching it to ResB on the cytoplasmic side of the membrane and then transferring it to an extra‐cytoplasmic location in ResC, from where it is made available to the apo‐cytochromes.