Absence of thiol-disulfide oxidoreductase DsbA impairs cbb3-type cytochrome c oxidase biogenesis in Rhodobacter capsulatus

Abstract: The thiol-disulfide oxidoreductase DsbA carries out oxidative folding of extra-cytoplasmic proteins by catalyzing the formation of intramolecular disulfide bonds. It has an important role in various cellular functions, including cell division. The purple non-sulfur bacterium Rhodobacter capsulatus mutants lacking DsbA show severe temperature-sensitive and medium-dependent respiratory growth defects. In the presence of oxygen, at normal growth temperature (35°C), DsbA− mutants form colonies on minimal medium, but they do not grow on enriched medium where cells elongate and lyse. At lower temperatures (i.e., 25°C), cells lacking DsbA grow normally in both minimum and enriched media, however, they do not produce the cbb3-type cytochrome c oxidase (cbb3-Cox) on enriched medium. Availability of chemical oxidants (e.g., Cu2+ or a mixture of cysteine and cystine) in the medium becomes critical for growth and cbb3-Cox production in the absence of DsbA. Indeed, addition of Cu2+ to the enriched medium suppresses, and conversely, omission of Cu2+ from the minimal medium induces, growth and cbb3-Cox defects. Alleviation of these defects by addition of redox-active chemicals indicates that absence of DsbA perturbs cellular redox homeostasis required for the production of an active cbb3-Cox, especially in enriched medium where bioavailable Cu2+ is scarce. This is the first report describing that DsbA activity is required for full respiratory capability of R. capsulatus, and in particular, for proper biogenesis of its cbb3-Cox. We propose that absence of DsbA, besides impairing the maturation of the c-type cytochrome subunits, also affects the incorporation of Cu into the catalytic subunit of cbb3-Cox. Defective high affinity Cu acquisition pathway, which includes the MFS-type Cu importer CcoA, and lower production of the c-type cytochrome subunits lead together to improper assembly and degradation of cbb3-Cox

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Frontiers in microbiology. - 8 (2017) , 02576, ISSN: 1664-302X

Classification and Topics

• Classification: Biowissenschaften, Biologie

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2023
• Creator: Önder, Özlem ; Verissimo, Andreia F. ; Khalfaoui-Hassani, Bahia ; Peters, Annette ; Koch, Hans-Georg ; Daldal, Fevzi

Further information

• DOI: 10.3389/fmicb.2017.02576
• URN: urn:nbn:de:bsz:25-freidok-1438107
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 14.08.2025, 10:49 AM CEST