Article

Beyond the Fur paradigm: iron-controlled gene expression in rhizobia.

Institute of Microbiology, Eidgenössische Technische Hochschule, Zürich, Switzerland.
FEMS Microbiology Reviews (impact factor: 10.96). 08/2006; 30(4):631-48. DOI:10.1111/j.1574-6976.2006.00030.x pp.631-48
Source: PubMed

ABSTRACT Iron is critical for bacterial growth, but problems arise from the toxicity of excess iron; thus, iron uptake is subject to tight control. The most widely found and best-studied iron-responsive regulator in Gram-negative bacteria is the ferric uptake regulator Fur. In recent years, however, it has become apparent that iron regulation in rhizobia differs from that in many other bacteria. New regulators (RirA, Irr, Mur) were identified which appear to mediate functions that in other bacteria are accomplished by Fur. Even though some of them belong to the Fur family, they exhibit properties that clearly separate them from genuine Fur proteins. This article surveys the principal mechanisms of iron acquisition and uptake in rhizobia, and puts particular emphasis on recent findings on transcriptional regulators and their means to sense the cellular iron status and to regulate gene expression. In this context, we point out differences and similarities with regard to the operators, regulons and structure of the discussed iron regulatory proteins.

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Keywords

bacterial growth
 
best-studied iron-responsive regulator
 
cellular iron status
 
differences
 
discussed iron regulatory proteins
 
excess iron
 
ferric uptake regulator Fur
 
gene expression
 
genuine Fur proteins
 
iron acquisition
 
iron regulation
 
iron uptake
 
New regulators
 
operators
 
particular emphasis
 
principal mechanisms
 
recent findings
 
recent years
 
separate
 
transcriptional regulators
 

Gesine Rudolph