Journal of Bacteriology & Parasitology

Host related iron acquisition in Bacillus cereus: The interplay between surface proteins and siderophores in iron grabbing from ferritin and hemoproteins

International Congress on Bacteriology & Infectious Diseases

November 20-22, 2013 DoubleTree by Hilton Baltimore-BWI Airport, MD, USA

Christina Nielsen Le Roux

Accepted Abstracts: J Bacteriol Parasitol

Abstract:

In host-pathogen interactions, the struggle for iron may have major consequences on the outcome of a disease. To cope with the low iron environment encountered in the host, bacteria have evolved multiple iron acquisition systems. Over the past 10 years, our understanding of iron import into Gram-positive bacteria has been greatly improved. The most impressive advances concern the mechanisms of heme acquisition via NEAT proteins. In the human opportunistic pathogen Bacillus cereus, a composite NEAT protein named IlsA (Ironregulated leucine rich surface protein A) was previously identified as a surface protein involved in bacterial virulence A, B. Unlike other NEAT proteins, IlsA is able to bind not only to heme and hemoglobin but also ferritin in vitro A. As ferritin can store thousands of iron atoms, pathogens able to use this iron source, get rapidly access to large amounts of iron. But the molecular basis of host-ferritin utilization by pathogens remains largely unknown. Here, we show that IlsA recognizes and interacts directly with the ferritin shell, altering the ferritin properties leading to an increase of the siderophores-mediated iron release from the ferritin nanocages. We also characterized the function of IlsA in heme acquisition and we demonstrated that the B. cereus Isd system (Iron surface determinants previously described in other Gram-positive bacteria) is a partner of IlsA in this process. Hence, our studies highlight the central role of IlsA in B. cereus iron acquisition and its interplay with other surface proteins and siderophores. We provide new insights into host adaptation of B. cereus and describe a unique molecule taking part in iron uptake modulation both in vivo and in vitro.

Biography :

Christina Nielsen Le Roux is agronomist from University of Copenhagen Denmark, and performed her Ph.D. training at Pasteur Institute and at the University Pierre & Marie Curie, Paris, France. She is specialized in host-pathogens interactions with focus on entomo‐pathogenic and human opportunistic spore forming bacilli. The identification and functions of various virulence and host adaptation factors have been the basis for more than 35 publications and several worldwide collaborations. She is senior scientist at INRA (French National institute for research in agronomy) close to Paris at the Center of Jouy-en-Josas.