Microbiology and Molecular Biology Reviews, March 2008, p. 110-125, Vol. 72, No. 1

SUMMARY
INTRODUCTION
CYSTEINE DESULFURASES
IscS
SufS and SufE
CsdA and CsdE
SCAFFOLD PROTEINS
U-Type Scaffolds
A-Type Scaffolds
MOLECLUAR CHAPERONES FOR FE-S CLUSTER ASSEMBLY
THE SufBCD COMPLEX
POSSIBLE IRON DONORS AND OTHER ACCESSORY PROTEINS
REGULATION OF FE-S CLUSTER ASSEMBLY
IscR
Oxygen and Oxidative Stress
Iron
FUNCTIONAL CROSS TALK BETWEEN PATHWAYS
OUTLOOK
In Vivo Iron Donation
Target Specificity
Role of Accessory Proteins
ACKNOWLEDGMENTS
REFERENCES

Iron-sulfur (Fe-S) clusters are required for critical biochemical pathways, including respiration, photosynthesis, and nitrogen fixation. Assembly of these iron cofactors is a carefully controlled process in cells to avoid toxicity from free iron and sulfide. Multiple Fe-S cluster assembly pathways are present in bacteria to carry out basal cluster assembly, stress-responsive cluster assembly, and enzyme-specific cluster assembly. Although biochemical and genetic characterization is providing a partial picture of in vivo Fe-S cluster assembly, a number of mechanistic questions remain unanswered. Furthermore, new factors involved in Fe-S cluster assembly and repair have recently been identified and are expanding the complexity of current models. Here we attempt to summarize recent advances and to highlight new avenues of research in the field of Fe-S cluster assembly.