The membrane QmoABC complex interacts directly with the dissimilatory adenosine 5'-phosphosulfate reductase in sulfate reducing bacteria
- Universidade Nova de Lisboa, Oeiras (Portugal). 1 Instituto de Tecnologia Química e Biológica
- Univ. of Missouri, Columbia, MO (United States). Biochemistry Dept.; Ecosystems and Networks Integrated with Genes and Molecular Assemblies, Berkeley, CA (United States)
The adenosine 5 -phosphosulfate reductase (AprAB) is the enzyme responsible for the reduction of adenosine 5 -phosphosulfate (APS) to sulfite in the biological process of dissimilatory sulfate reduction, which is carried out by a ubiquitous group of sulfate reducing prokaryotes. The electron donor for AprAB has not been clearly identified, but was proposed to be the QmoABC membrane complex, since an aprBA–qmoABC gene cluster is found in many sulfate reducing and sulfur-oxidizing bacteria. The QmoABC complex is essential for sulfate reduction, but electron transfer between QmoABC and AprAB has not been reported. In this work we provide the first direct evidence that QmoABC and AprAB interact in Desulfovibrio spp., using co-immunoprecipitation, cross-linking FarWestern blot, tag-affinity purification, and surface plasmon resonance studies.This showed that the QmoABC–AprAB complex has a strong steady-state affinity (K D = 90 ± 3 nM), but has a transient character due to a fast dissociation rate. Far-Western blot identified QmoA as the Qmo subunit most involved in the interaction. Nevertheless, electron transfer from menaquinol analogs to APS through anaerobically purified QmoABC and AprAB could not be detected. We propose that this reaction requires the involvement of a third partner to allow electron flow driven by a reverse electron bifurcation process, i.e., electron confurcation. This process is deemed essential to allow coupling of APS reduction to chemiosmotic energy conservation.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of Missouri, Columbia, MO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division
- Grant/Contract Number:
- AC02-05CH11231; FG02-08ER64691
- OSTI ID:
- 1628058
- Journal Information:
- Frontiers in Microbiology, Vol. 3; ISSN 1664-302X
- Publisher:
- Frontiers Research FoundationCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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