Open Access Research article

Identification of the type II cytochrome c maturation pathway in anammox bacteria by comparative genomics

Christina Ferousi1, Daan R Speth1, Joachim Reimann1, Huub JM Op den Camp1, James WA Allen2, Jan TM Keltjens1 and Mike SM Jetten1*

Author Affiliations

1 Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525, AJ, Nijmegen, the Netherlands

2 Department of Biochemistry, University of Oxford, South Parks Road, OX13QU Oxford, UK

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BMC Microbiology 2013, 13:265  doi:10.1186/1471-2180-13-265

Published: 23 November 2013



Anaerobic ammonium oxidizing (anammox) bacteria may contribute up to 50% to the global nitrogen production, and are, thus, key players of the global nitrogen cycle. The molecular mechanism of anammox was recently elucidated and is suggested to proceed through a branched respiratory chain. This chain involves an exceptionally high number of c-type cytochrome proteins which are localized within the anammoxosome, a unique subcellular organelle. During transport into the organelle the c-type cytochrome apoproteins need to be post-translationally processed so that heme groups become covalently attached to them, resulting in mature c-type cytochrome proteins.


In this study, a comparative genome analysis was performed to identify the cytochrome c maturation system employed by anammox bacteria. Our results show that all available anammox genome assemblies contain a complete type II cytochrome c maturation system.


Our working model suggests that this machinery is localized at the anammoxosome membrane which is assumed to be the locus of anammox catabolism. These findings will stimulate further studies in dissecting the molecular and cellular basis of cytochrome c biogenesis in anammox bacteria.

Cytochrome c biogenesis; Anaerobic ammonium oxidizing bacteria; ccs; CcsA; CcsB; CcsX; DsbD; CcdA