Skip to main content.
 

Abstract's Details

Structure of the Mn(IV)/Fe(III) Cofactor of the Chlamydia trachomatis Ribonucleotide Reductase
Abstract IDBIO-02 
PresenterCourtney  Krest
Presentation TypePoster
Full Author ListC. Krest (1), J. Younker (1), W. Jiang (2), C. Krebs (2), J. M. Bollinger Jr. (2), M. Green (1)
Affiliations(1) Penn State University, Dept. of Chemistry
(2) Penn State University, Dept. of Biochemistry and Molecular Biology
CategoryBio/Life Sciences
AbstractIn class I ribonucleotide reductases, such as that from E. coli, the R2 cofactor has a diiron center. It also features a tyrosine radical that initiates thiyl radical formation in R1. However, Roshick et al.1, using sequence comparisons, and Högbom et al.2, using the crystal structure, discovered that the ribonucleotide reductase of Chlamydia trachomatis lacks the essential class Ia tyrosine. Later, Jiang et al. 3-5 showed that the R2 of C. trachomatis was actually a manganese iron dinuclear center rather than a diiron center. They reconstituted C. trachomatis R2, and restored maximum activity using a metal ratio of one Mn and one Fe, and characterized this novel dinuclear site using 57Fe Mössbauer and EPR.

We have utilized XAS coupled with DFT calculations to determine the structure of the Mn(IV)/Fe(III) state of this novel diamond core. A ~2.9Å metal-metal distance was obtained from EXAFS measurements. A short Mn-O distance of ~1.72Å was also found. Both distances are in good agreement with the results obtained from DFT calculations. Our current model for the Mn(IV)-Fe(III) cluster includes an oxo bridge, a hydroxo bridge, and a bridging carboxylate.
Footnotes1. Roshick, C.; Iliffe-Lee, E. R.; McClarty, G. J. Biol. Chem. 2000, 275, 38111-38119.
2. Högbom, M.; Stenmark, P.; Voevodskaya, N.; McClarty, G.; Graslund, A.; Nordlund, P. Science 2004, 305, 245-248.
3. Jiang, W.; Bollinger, J.M.; Krebs,C. J. Am. Chem. Soc. 2007, 129, 7504-7505.
4. Jiang, W.; Yun, D; Saleh, L; Barr, E; Xing, G; Hoffart, L; Maslak, MA; Krebs, C; Bollinger, M;. Science 2007, 316, 1188-1191.
5. Jiang, W.; Hoffart, L; Bollinger, J.M.; C Krebs. Biochemistry, 2007/.  
Funding AcknowledgementThis work was supported by the Beckman Foundation, Young Investigator Award.