Biosciences and Biotechnology Institute of Aix-Marseille
Research Topic, MEM
Pascal ARNOUX, Mila KOJADINOVIC, Monique SABATY & David PIGNOL
Technician/Ingineer : Sandrine GROSSE,& Catherine BRUTESCO
PhD Student:: Pierre-Xavier MAZIANI
Posdoc: Lionel TARRAGO
Two Molybdo-enzymes from Rhodobacter sphaeroides Rb are characterized: (i) the periplasmic nitrate reductase (NapAB) which can reduce nitrate but also selenium oxide, and (ii) MsrP, an oxidoreductase playing a role in the repair of oxidative stress induced by the metallic stress. These metalloproteins are studied at the structural (1), biochemical (2,3, 15) and biophysical (4, 5, 6, 7, 8, 9, 14) levels. A project funded by the National Research Agency (ANR MC2, MOLYERE and METOXIC) aims at understanding the substrate specificity of these metalloproteins.
Metals are required in almost every life processes
and therefore all life forms have developed some mechanisms of metal
acquisition. We focusse on the characterization of orignial metal uptake in bacteria.
Nicotianamine (NA) is a small molecule present in all plants. NA binds various metal ions such as Cu2+ Zn2+ Mn2+ and Ni2+. Nicotianamine synthase (NAS) catalyzes the biosynthesis of NA by condensation of three molecules of S-adenosylmethionine. Usinga structural approach on an archeal enzyme related to eukaryotic NAS, we were able to describe for the first time a unique enzymatic mechanism responsible for the synthesis of NA (10,11,12). Similar study on NAS-like from bacteria is currently underway.
the nicotianamine synthase (NAS) family, together with an extensive
genomic analysis allowed us to propose the existence of NAS-Like enzymes in the
bacterial domain. Studying this system through metabolomic exploration,
targeted mutagenesis, and biochemical analysis, we uncovered an operon in Staphylococcus aureus that encodes the
different functions required for the biosynthesis and trafficking (export and
import systems) of a broad-spectrum NA-like metallophore (coined staphylopine).
Biosynthesis of staphylopine requires the association of three unprecedented
enzyme activities. We further demonstrated that staphylopine is involved in
nickel, cobalt, zinc, copper and iron acquisition, depending on the growth
conditions. Because this biosynthetic pathway is conserved in several pathogens
our work underscores the importance of this metal acquisition strategy in bacterial
infection. This discovery was recently accepted for
publication in the journal Science (18) and paves the way to numerous potential biomedical applications .
G, Brutesco C, Ouerdane L, Fojcik C, Izaute A, Hajjar C, Lobinski R, Lemaire D, Richaud P, Voulhoux R, Espaillat A, Cava
F, Pignol D, Borezee-Durant
E & Arnoux P (2016) Biosynthesis of a broad-spectrum
nicotianamine-like metallophore in Staphylococcus aureus. Science May 27;352(6289):1105-9. doi: 10.1126/science.aaf1018.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.