Project description:Mesorhizobium metallidurans STM 2683 and Mesorhizobium sp. strain STM 4661 were isolated from nodules of the metallicolous legume Anthyllis vulneraria from distant mining spoils. They tolerate unusually high zinc and cadmium concentrations as compared to other mesorhizobia. This work aims to study the gene expression profiles associated with zinc or cadmium exposure and to identify genes involved in metal tolerance in these two metallicolous Mesorhizobium strains of interest for mine phytostabilization purposes. Mesorhizobium metallidurans STM 2683 and Mesorhizobium sp. strain STM 4661 with three treatments (control, Zn and Cd).
Project description:Mesorhizobium metallidurans STM 2683 and Mesorhizobium sp. strain STM 4661 were isolated from nodules of the metallicolous legume Anthyllis vulneraria from distant mining spoils. They tolerate unusually high zinc and cadmium concentrations as compared to other mesorhizobia. This work aims to study the gene expression profiles associated with zinc or cadmium exposure and to identify genes involved in metal tolerance in these two metallicolous Mesorhizobium strains of interest for mine phytostabilization purposes.
Project description:Zinc is a central player in the metalloproteomes of prokaryotes and eukaryotes. We used a top-down quantitative proteomic approach to reveal the repository of the zinc pools in the proteobacterium Cupriavidus metallidurans. About 60% of the theoretical proteome of C. metallidurans were identified, quantified, and compared between a ΔzupT mutant defect in zinc allocation and its parent strain. In both strains, the number of zinc-binding proteins and their binding sites exceeded that of the zinc ions per cell, indicating that the totality of the zinc proteome provides empty binding sites for incoming zinc ions. This zinc repository plays a central role in zinc homeostasis in C. metallidurans and probably also in other organisms.
Project description:Different Cupriavidus metallidurans strains isolated from metal-contaminated and other anthropogenic environments were genotypically and phenotypically compared with C. metallidurans type strain CH34. The latter is well-studied for its resistance to a wide range of metals, which is carried for a substantial part by its two megaplasmids pMOL28 and pMOL30. Comparative genomic hybridization (CGH) indicated that the extensive arsenal of determinants involved in metal resistance was well conserved among the different C. metallidurans strains. Contrary, the mobile genetic elements identified in type strain CH34 were not present in all strains but clearly showed a pattern, although, not directly related to a particular biotope nor location (geographical). One group of strains carried almost all mobile genetic elements, while these were much less abundant in the second group. This occurrence was also reflected in their ability to degrade toluene and grow autotrophically on hydrogen gas and carbon dioxide, which are two traits linked to separate genomic islands of the Tn4371-family. In addition, the clear pattern of genomic islands distribution allowed to identify new putative genomic islands on chromosome 1 and 2 of C. metallidurans CH34. Metal resistance determinants are shared by all C. metallidurans strains and their occurrence is apparently irrespective of the strain's isolation type and place. Cupriavidus metallidurans strains do display substantial differences in the diversity and size of their mobile gene pool, which may be extensive in some (including the type strain) while marginal in others.
