How do bacteria distribute metals to correct target enzymes while remaining tolerant to metal toxicity?

Metalloenzymes carry out essential reactions, and their mismetallation has deleterious effects. In consequence, a primary cellular requirement is to target cognate metals to the corresponding targets. On the other hand, free redox active metals generate harmful free radicals, with the associated fitness cost These place metal sensing, chaperoning, storage, and transmembrane transport at the forefront of cell chemistry and biology. We hypothesize that these mechanisms are integrated in system wide distribution networks. In turn, these translocate the ion into accepting periplasmic chaperones. We aim now to understand the architecture and dynamics of these distribution networks.

How do bacteria metal homeostasis mechanisms determine survival in the challenging phagosomal environment of eukaryote hosts?

Mechanisms of innate immunity include higher Zn²⁺ and Cu⁺ levels and an oxidative burst that leads to Fe-S center disruption with a consequent high cytoplasmic Fe²⁺. We have observed that various distinct transition metal ATPases are present in pathogenic organisms; for instance the unique Fe²⁺ ATPases and the Mn²⁺ ATPase in Mycobacterium tuberculosis. We hypothesize that pathogenic organisms have a more diverse arrange of metal transporters and homeostatic mechanism participating not just in metal tolerance but also in coping with the oxidative bust by metallation of critical enzymes.

How does the structure of metal transport membrane ATPases determine their functional characteristics?

The study of metal transport P1B-ATPases has been the core of our laboratory since its beginning. Employing as a model Archaeoglobus fulgidus CopA, a thermophilic Cu⁺-ATPase, we established the catalytic mechanisms, transport stoichiometry, structure and function of soluble domains, and the structure of metal transport sites in the transmembrane region of these enzymes. We showed the specificity and the determining structures in distinct subfamilies of Zn²⁺, Cu²⁺, Ni²⁺, Mn²⁺ and Fe²⁺ ATPases. Moving forward, we attempt to understand the chemical interactions and resulting forces that drive the movement of transition metal along dehydrated protein permeation paths.