FUNCTIONAL STUDIES OF THE FE-S CLUSTER BIOGENESIS BY SUF SYSTEM

Iron-Sulfur clusters are important metal cofactors for many enzymes. Bacteria have dedicated systems for the maturation and trafficking of Fe-S clusters. The SUF (Sulfur Utilization Factor) system is the only housekeeping system in Gram-positive bacteria; whereas in Gram-negative bacteria, the SUF system acts as an auxiliary role to housekeeping ISC (Iron Sulfur Cluster) system and becomes active only during oxidative stress and iron starvation conditions. In both systems, the first step of sulfur mobilization is catalyzed by the cysteine desulfurase SufS, which transfers the sulfur from the free amino acid cysteine to specific sulfur acceptor proteins. Despite similarities in their general reaction schemes, the proteins and mechanisms involving the second reaction step are distinct. In this work, we have performed the kinetic analysis of sulfur transfer reaction of the Escherichia coli and compared to that characterized for the Bacillus subtilis SUF system. In the E. coli system, sequential sulfur transfer reactions from SufSSufESufBCD are partially protected from the action of reducing agents such as DTT and glutathione. Under these conditions, the reaction profile shows a biphasic behavior, where the second phase of the reaction is associated with the accumulation of persulfurated/polysulfurated forms of SufE. In B. subtilis, kinetic and labeling experiments indicated that, unlike E. coli SufS-SufE, the sulfurtransferase reaction by SufS-SufU is not protected from the action of reducing agents.

Grantor dc:publisher

Wake Forest University

Year dc:date.issued

2016

Author dc:creator

• Pradhan, Pradyumna K.

• cysteine desulfurase

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10339/64194

OAI identifier oai:identifier

oai:wakespace.lib.wfu.edu:10339/64194