Iron as a candidate in virulence and pathogenesis in mycobacteria and other microorganisms

Abstract

Iron acquisition is one of the important virulence characteristics of a pathogen. Microorganisms elaborate different ways of acquiring iron. Siderophore-mediated iron acquisition is common in many microorganisms, while some like Neisseriae directly acquire iron from the host proteins. Microorganisms also elaborate systems for iron acquisition from ferric citrate and xenosiderophores. Such modes of uptake are also seen in mycobacteria. The siderophores produced by mycobacteria are well characterised. Iron-regulated envelope proteins (IREPs) are expressed in both saprophytic and pathogenic mycobacteria. In many bacterial systems, like that of Corynebacterium diphtheriae, low iron conditions favour the expression of virulence factors. The siderophore mycobactin has been recently implicated as a virulence factor in Mycobacterium tuberculosis. The role of the IdeR repressor in controlling the expression of the iron acquisition machinery was studied with the generation of the IdeR mutant. Development of other such mutants will facilitate the study of these mechanisms in greater detail and help to develop new drugs for combating tuberculosis and leprosy.