Tellurite (TeO32−) is an oxyanion of increasing concern for soils and water bodies as tellurite is toxic to prokaryotes and eukaryotes. In cells of Rhodobacter capsulatus, a facultative anoxygenic photosynthetic bacterium which tolerates up to 1 mM tellurite, the assembly of c-type cytochromes (cyts) occurs in the periplasm and involves several proteins ensuring the correct redox-state of the cyt cmaturation process (Ccm). Here it is shown that a sub-lethal tellurite concentration (0.2 mM) reduces the amount of cyts c during the early growth-phase of R. capsulatus. This effect is due to a malfunction of the Ccm system and not to an effect on the transcriptional expression of the cyt c genes. Further, growth of mutants MT-G4/S4 and MD21, with mutations at the level of cyt c2 (ΔcycA) and of the Ccm system (ΔdsbA/ΔccdA), respectively, was more affected by tellurite than wild type cells. Both MT-G4/S4 and MD21 mutants, featured by a cyt c2 deficiency, showed a significant decrease in their capacity to reduce TeO32− into Te0, thereby implying the need of a full amount of periplasmic cyt c2 in the microbial-driven speciation of the metalloid. These findings show, for the first time, that tellurite processing by cells starts at the periplasmic level.
Borsetti, F., Borghese, R., Cappelletti, M., Zannoni, D. (2018). Tellurite processing by cells of Rhodobacter capsulatus involves a periplasmic step where the oxyanion causes a malfunction of the cytochrome c maturation system. INTERNATIONAL BIODETERIORATION & BIODEGRADATION, 130, 1-7 [10.1016/j.ibiod.2018.04.002].
Tellurite processing by cells of Rhodobacter capsulatus involves a periplasmic step where the oxyanion causes a malfunction of the cytochrome c maturation system
Borsetti, Francesca;Borghese, Roberto;Cappelletti, Martina;Zannoni, Davide
2018
Abstract
Tellurite (TeO32−) is an oxyanion of increasing concern for soils and water bodies as tellurite is toxic to prokaryotes and eukaryotes. In cells of Rhodobacter capsulatus, a facultative anoxygenic photosynthetic bacterium which tolerates up to 1 mM tellurite, the assembly of c-type cytochromes (cyts) occurs in the periplasm and involves several proteins ensuring the correct redox-state of the cyt cmaturation process (Ccm). Here it is shown that a sub-lethal tellurite concentration (0.2 mM) reduces the amount of cyts c during the early growth-phase of R. capsulatus. This effect is due to a malfunction of the Ccm system and not to an effect on the transcriptional expression of the cyt c genes. Further, growth of mutants MT-G4/S4 and MD21, with mutations at the level of cyt c2 (ΔcycA) and of the Ccm system (ΔdsbA/ΔccdA), respectively, was more affected by tellurite than wild type cells. Both MT-G4/S4 and MD21 mutants, featured by a cyt c2 deficiency, showed a significant decrease in their capacity to reduce TeO32− into Te0, thereby implying the need of a full amount of periplasmic cyt c2 in the microbial-driven speciation of the metalloid. These findings show, for the first time, that tellurite processing by cells starts at the periplasmic level.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
