Metal Uptake & Metallochaperones

Nickel Uptake

Trace metals are essential for life. Organisms must obtain sufficient quantities of trace metals for growth, while preventing the accumulation of excess metal which can be toxic to the cell. Our laboratory is interested in understanding the regulation of cellular metal uptake, and we have begun our studies by investigating Ni uptake in E. coli. Here, nickel concentrations are controlled by transcriptional repression of the nickel-specific ABC transporter. In the presence of excess intracellular nickel, the nickel-dependent repressor NikR binds to an operator sequence, turning off expression of the transporter and decreasing nickel import. To gain insight into how nickel regulates NikR function, we are determining crystal structures apo NikR, nickel-bound NikR by itself, and the NikR:DNA complex.

Full-length apo-NikR

Full-length apo-NikR

Metal-binding domainof NikR with Ni bound

Metal-binding domain
of NikR with Ni bound

Publications

Phillips CM, Schreiter ER, Stultz CM, and Drennan CL. (2010) Structural Basis of Low Affinity Nickel Binding to the Nickel-Responsive Transcription Factor NikR fromEscherichia coli. Biochemistry. 49:7830-7838.

Schreiter, E.R., Sintchak, M.D., Guo, Y., Chivers, P.T., Sauer, R.T., and Drennan, C.L. (2003),Crystal Structure of the Nickel-Responsive Transcription Factor NikR, Nature Structural Biology.10:794-799.

Schreiter, E.R, Wang, S. C., Zamble, D.B., Drennan, C.L. (2006) NikR-operator complex structure and the mechanism of repressor activation by metal ions, Proceedings of the National Academy of Science U.S.A 103:13676-13681.

Phillips, C.M., Schreiter, E.R., Guo, Y., Wang, S.C., Zamble, D.B., Drennan, C.L. (2008)Structural Basis of the Metal Specificity for Nickel Regulatory Protein NikR, Biochemistry.47(7):1938-1946.

 

Nickel Import in Escherichia Coli

Nickel Import in Escherichia Coli

Iron-Sulfur Cluster Assembly

Iron sulfur clusters are ubiquitous cofactors involved in key cellular processes such as electron transfer, gene regulation, and adenosyl- methionine-dependent radical chemistry. These clusters can form spontaneously in vitro from aqueous iron (II) and sulfide; however, the in vivo toxicity of these species requires strict regulation during cluster assembly. We are interested in elucidating the structures and mechanisms of proteins involved in iron-sulfur cluster assembly inSynechocystis. Thus far, we have determined the structure of the essential cysteine desulfurase fromSynechocystis to 1.8Å resolution.

Cysteine Desulfurase

Cysteine Desulfurase

Publications

Tirupati, B., Vey , J. L., Drennan, C. L., Bollinger, Jr., J.M. (2004) Kinetic and Structural Characterization of Slr0077/SufS, the Essential Cysteine Desulfurase fromSynechocystis sp. PCC 6803Biochemistry. 43:12210-12219.