Cu Transport by the Extended Family of CcoA-like Transporters (CalT) in Proteobacteria

Yang Zhang (1, 2) , Crysten E Blaby-Haas (3) , Stefan Steimle (1) , Andreia F Verissimo (1) , Victor A Garcia-Angulo (4) , Hans-Georg Koch (5) , Fevzi Daldal (1) , B.K. Hassani (6)

1 University of Pennsylvania
2 Xiamen University
3 BNL - Brookhaven National Laboratory [Upton, NY]
4 UCHILE - Universidad de Chile = University of Chile [Santiago]
5 Albert-Ludwigs-Universität Freiburg
6 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux

Comparative genomic studies of the bacterial MFS-type copper importer CcoA, required for cbb3-type cytochrome c oxidase (cbb3-Cox) biogenesis, revealed a widespread CcoA-like transporters (CalT) family, containing the conserved CcoA Cu-binding MxxxM and HxxxM motifs. Surprisingly, this family also included the RfnT-like proteins, earlier suggested to transport riboflavin. However, presence of the Cu-binding motifs in these proteins raised the possibility that they might be Cu transporters. To test this hypothesis, the genomic context of the corresponding genes was examined, and three of such genes from Ochrobactrum anthropi, Rhodopseudomonas palustris and Agrobacterium tumefaciens were expressed in Escherichia coli (ΔribB) and Rhodobacter capsulatus (ΔccoA) mutants. Copper and riboflavin uptake abilities of these strains were compared with those expressing R. capsulatus CcoA and Rhizobium leguminosarum RibN as bona fide copper and riboflavin importers, respectively. Overall data demonstrated that the “RfnT-like” CalT proteins are unable to efficiently transport riboflavin, but they import copper like CcoA. Nevertheless, even though expressed and membrane-localized in a R. capsulatus mutant lacking CcoA, these transporters were unable to accumulate Cu or complement for cbb3-Cox defect. This lack of functional exchangeability between the different subfamilies of CalT homologs suggests that MFS-type bacterial copper importers might be species-specific.

Domaines: Génomique, Transcriptomique et Protéomique [q-bio.GN]; Bactériologie

Yang Zhang, Crysten E Blaby-Haas, Stefan Steimle, Andreia F Verissimo, Victor A Garcia-Angulo, et al.. Cu Transport by the Extended Family of CcoA-like Transporters (CalT) in Proteobacteria. Scientific Reports, 2019, 9 (1), pp.1208. ⟨10.1038/s41598-018-37988-4⟩. ⟨hal-02022668⟩