Methionine Implication In Rhizobial Iron Acquisition from Hemoglobin

Iron is an essential metal for almost all living cells. In the interaction host-parasite, this metal is considered as a key element. The possession of highly efficient mechanisms to overcame the natural iron limitation imposed by the host, is critical for the parasite survival. Some parasite use siderophore to strip iron from the carrier proteins while others have evolved heme-mediated iron acquisition mechanisms. Although these mechanisms are complex and diverse, the presence of outer membrane receptors for iron compounds seems to be a general phenomenon. Despite the expanded understanding on the association rhizobia-legume, the knowledge of iron acquisition mechanism is one of the major interests of our group. We almost demonstrated that rhizobia were able to utilize hemin, hemoglobin, mioglobin leghemoglobin and siderophores (rhizobactin 242 and ferrichrome) as iron sources. Moreover, the uptake mechanism of these compounds share at least one component. According our previous work, it is conceivable that this component could be a protein from the Ton complex. These data support the idea that many of the processes found in the interaction rhizobialeguminous host, are variant of general processes implicated in other microand macroorganisms interactions. The present work aimed at the elucidation of the physiology and biochemistry of iron transport in rhizobia. In this study we examined the utilization of heme compounds and siderophores as iron sources in Sinorhizobium meliloti 242 grown on minimal medium.