title: IlsA, a unique surface protein of Bacillus cereus required for iron acquisition from heme, hemoglobin and ferritin.
abstract: The human opportunistic pathogen Bacillus cereus belongs to the B. cereus group that includes bacteria with a broad host spectrum. The ability of these bacteria to colonize diverse hosts is reliant on the presence of adaptation factors. Previously, an IVET strategy led to the identification of a novel B. cereus protein (IlsA, Iron-regulated leucine rich surface protein), which is specifically expressed in the insect host or under iron restrictive conditions in vitro. Here, we show that IlsA is localized on the surface of B. cereus and hence has the potential to interact with host proteins. We report that B. cereus uses hemoglobin, heme and ferritin, but not transferrin and lactoferrin. In addition, affinity tests revealed that IlsA interacts with both hemoglobin and ferritin. Furthermore, IlsA directly binds heme probably through the NEAT domain. Inactivation of ilsA drastically decreases the ability of B. cereus to grow in the presence of hemoglobin, heme and ferritin, indicating that IlsA is essential for iron acquisition from these iron sources. In addition, the ilsA mutant displays a reduction in growth and virulence in an insect model. Hence, our results indicate that IlsA is a key factor within a new iron acquisition system, playing an important role in the general virulence strategy adapted by B. cereus to colonize susceptible hosts.
authors: INRA-UR1249 Génétique Microbienne et Environnement, La Minière, Guyancourt, France.
authors: Nadine
authors: N
authors: Daou
authors: Christophe
authors: C
authors: Buisson
authors: Michel
authors: M
authors: Gohar
authors: Jasmina
authors: J
authors: Vidic
authors: Hélène
authors: H
authors: Bierne
authors: Mireille
authors: M
authors: Kallassy
authors: Didier
authors: D
authors: Lereclus
authors: Christina
authors: C
authors: Nielsen-LeRoux
mesh_terms: D000818:Animals; D001409:Bacillus cereus / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D001426:Bacterial Proteins / Q000378:metabolism*; D002460:Cell Line; D005293:Ferritins; D006418:Heme; D006454:Hemoglobins; D007313:Insecta; D007501:Iron / Q000378:metabolism*; D007781:Lactoferrin; D014168:Transferrin
chemical_list: D001426:Bacterial Proteins; D006454:Hemoglobins; D014168:Transferrin; D006418:Heme; D005293:Ferritins; D007501:Iron; D007781:Lactoferrin