서강대학교

초록 (요약문)

IscR is a well-known transcription factor controlling the expression of Fe-S cluster systems. It also regulates the expression of virulence factors in Vibrio vulnificus, and its presence is required for successful infection to a model animal. Thus, appropriate levels of IscR should be present in cells upon entry to host environments, where irons available to pathogens are critically limited. For this, V. vulnificus maintains high iscR expression under iron-deprived conditions through iron-sensing regulatory systems. In this study, a regulatory mechanism for iscR expression was elucidated at the transcription level. Expression profiles of cellular IscR showed that its level was maximal at the exponential phase and then decreased to an undetectable level during the stationary phase. Stationary-phase repression of the iscR expression was relieved when an iron-chelator was added. This repressive effect of iron ions on the iscR expression was mediated by the observed in both exponential- and stationary-phase cells. However, measurement of the cellular iron revealed that the concentration of ferrous ions was significantly higher in stationary-phase cells than in exponential-phase cells. Therefore, this study proposes that the degree of the iscR expression is controlled by the concentration of ferrous ions via transition of iron-complex states of Fur.