Iron Acquisition in Bacillus cereus: The Roles of IlsA and Bacillibactin in Exogenous Ferritin Iron Mobilization

PLoS Pathogens

Elise Abi Khalil¹  Christina Nielsen Le Roux¹  Nadine Daou¹  Paolo Arosio¹  Didier Lereclus²  Diego Segond²  Christophe Buisson²  Fadi Bou-Abdallah²  Mireille Kallassy³ 

[1]AgroParisTech, UMR Micalis, Jouy en Josas, France

[2]INRA, UMR 1319 Micalis, La Minière, Guyancourt, France

[3]Laboratory of Biotechnology, Saint-Joseph University, Beyrouth, Lebanon

关键词: Ferritin;    Bacillus cereus;    Iron;    Insects;    Bacterial pathogens;    Plasmid construction;    Heme;    Larvae;   

DOI  :  10.1371/journal.ppat.1003935

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

In host-pathogen interactions, the struggle for iron may have major consequences on the outcome of the disease. To overcome the low solubility and bio-availability of iron, bacteria have evolved multiple systems to acquire iron from various sources such as heme, hemoglobin and ferritin. The molecular basis of iron acquisition from heme and hemoglobin have been extensively studied; however, very little is known about iron acquisition from host ferritin, a 24-mer nanocage protein able to store thousands of iron atoms within its cavity. In the human opportunistic pathogen Bacillus cereus, a surface protein named IlsA (Iron-regulated leucine rich surface protein type A) binds heme, hemoglobin and ferritin in vitro and is involved in virulence. Here, we demonstrate that IlsA acts as a ferritin receptor causing ferritin aggregation on the bacterial surface. Isothermal titration calorimetry data indicate that IlsA binds several types of ferritins through direct interaction with the shell subunits. UV-vis kinetic data show a significant enhancement of iron release from ferritin in the presence of IlsA indicating for the first time that a bacterial protein might alter the stability of the ferritin iron core. Disruption of the siderophore bacillibactin production drastically reduces the ability of B. cereus to utilize ferritin for growth and results in attenuated bacterial virulence in insects. We propose a new model of iron acquisition in B. cereus that involves the binding of IlsA to host ferritin followed by siderophore assisted iron uptake. Our results highlight a possible interplay between a surface protein and a siderophore and provide new insights into host adaptation of B. cereus and general bacterial pathogenesis.

【 授权许可】

CC BY