Siderophores are small, high-affinity iron chelators produced by most bacteria, enabling them to grow underconditions of iron limitation. Pyoverdins (pvd), the complex, fluorescent siderophores of fluorescentpseudomonads are known to play an important role in virulence (P.aeruginosa) and in competitiveness in therhizosphere (P.fluorescens, P.putida). So far, nothing is known about the transport of siderophores fiom thecytoplasm through the cytoplasmic membrane (and to the outer membrane from gram-negative bacteria). Werecently identified a gene, cytl, coding for an inner membrane protein which is involved in both haem and pvdtransport across the inner membrane, to the periplasm of P.fluorescens ATCC 17400. We could howevernot identify the ABC (ATP Binding Cassette) component(s) which should be associated with the Cyt 1protein in a way typical of bacterial ABC-transport systems. Since a conserved periplasmic motif (haem-binding motif) was found by in vitro mutagenesis to be crucial for pyoverdin and l~n transpoTt, we intendto perform saturation mutagenesis of different residues in this motif in order to identify which amino acidsare important for pvd and haem excretion respectively. Production of antibodies against this periplasmicloop with use of a novel expression vector developed in our lab to produce immunogenic outer membranefusion lipoproteins will allow us to detect the association of Cyt 1 with other proteins in the cytoplasm, theperiplasm or the outer membrane. Finally a search will be made for similar proteins in P.aen~ginosa, animportant nosocomial pathogen, and in E.coli, in order to determine if Cyt I belongs to a family of proteinsinvolved in siderophore excretion.
|Effective start/end date||1/01/97 → 31/12/97|
Flemish discipline codes
- Earth sciences