Redox-Linked Structural Changes in Ribonucleotide Reductase
Ribonucleotide reductase (RNR) catalyzes the reduction of ribonucleotides to deoxyribonucleotides. Class I RNRs are composed of two homodimeric proteins, α2 and β2. The class Ia E. coli β2 contains dinuclear, antiferromagnetically coupled iron centers and one tyrosyl free radical, Y122•/β2. Y122• ac...
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| Format: | Article |
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American Chemical Society (ACS)
2013
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| Online Access: | http://hdl.handle.net/1721.1/82563 https://orcid.org/0000-0001-8076-4489 |
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| author | Offenbacher, Adam R. Vassiliev, I. R. Barry, Bridgette A. Stubbe, JoAnne Seyedsayamdost, Mohammad R. |
| author2 | Massachusetts Institute of Technology. Department of Biology |
| author_facet | Massachusetts Institute of Technology. Department of Biology Offenbacher, Adam R. Vassiliev, I. R. Barry, Bridgette A. Stubbe, JoAnne Seyedsayamdost, Mohammad R. |
| author_sort | Offenbacher, Adam R. |
| collection | MIT |
| description | Ribonucleotide reductase (RNR) catalyzes the reduction of ribonucleotides to deoxyribonucleotides. Class I RNRs are composed of two homodimeric proteins, α2 and β2. The class Ia E. coli β2 contains dinuclear, antiferromagnetically coupled iron centers and one tyrosyl free radical, Y122•/β2. Y122• acts as a radical initiator in catalysis. Redox-linked conformational changes may accompany Y122 oxidation and provide local control of proton-coupled electron transfer reactions. To test for such redox-linked structural changes, FT-IR spectroscopy was employed in this work. Reaction-induced difference spectra, associated with the reduction of Y122• by hydroxyurea, were acquired from natural abundance, [superscript 2]H[subscript 4] tyrosine, and [superscript 15]N tyrosine labeled β2 samples. Isotopic labeling led to the assignment of a 1514 cm[superscript −1] band to the υ19a ring stretching vibration of Y122 and of a 1498 cm[superscript −1] band to the υ7a CO stretching vibration of Y122•. The reaction-induced spectra also exhibited amide I bands, at 1661 and 1652 cm[superscript −1]. A similar set of amide I bands, with frequencies of 1675 and 1651 cm[superscript −1], was observed when Y• was generated by photolysis in a pentapeptide, which matched the primary sequence surrounding Y122. This result suggests that reduction of Y122• is linked with structural changes at nearby amide bonds and that this perturbation is mediated by the primary sequence. To explain these data, we propose that a structural perturbation of the amide bond is driven by redox-linked electrostatic changes in the tyrosyl radical aromatic ring. |
| first_indexed | 2024-09-23T16:44:09Z |
| format | Article |
| id | mit-1721.1/82563 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:44:09Z |
| publishDate | 2013 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/825632022-10-03T07:54:10Z Redox-Linked Structural Changes in Ribonucleotide Reductase Offenbacher, Adam R. Vassiliev, I. R. Barry, Bridgette A. Stubbe, JoAnne Seyedsayamdost, Mohammad R. Massachusetts Institute of Technology. Department of Biology Massachusetts Institute of Technology. Department of Chemistry Seyedsayamdost, M. R. Stubbe, JoAnne Ribonucleotide reductase (RNR) catalyzes the reduction of ribonucleotides to deoxyribonucleotides. Class I RNRs are composed of two homodimeric proteins, α2 and β2. The class Ia E. coli β2 contains dinuclear, antiferromagnetically coupled iron centers and one tyrosyl free radical, Y122•/β2. Y122• acts as a radical initiator in catalysis. Redox-linked conformational changes may accompany Y122 oxidation and provide local control of proton-coupled electron transfer reactions. To test for such redox-linked structural changes, FT-IR spectroscopy was employed in this work. Reaction-induced difference spectra, associated with the reduction of Y122• by hydroxyurea, were acquired from natural abundance, [superscript 2]H[subscript 4] tyrosine, and [superscript 15]N tyrosine labeled β2 samples. Isotopic labeling led to the assignment of a 1514 cm[superscript −1] band to the υ19a ring stretching vibration of Y122 and of a 1498 cm[superscript −1] band to the υ7a CO stretching vibration of Y122•. The reaction-induced spectra also exhibited amide I bands, at 1661 and 1652 cm[superscript −1]. A similar set of amide I bands, with frequencies of 1675 and 1651 cm[superscript −1], was observed when Y• was generated by photolysis in a pentapeptide, which matched the primary sequence surrounding Y122. This result suggests that reduction of Y122• is linked with structural changes at nearby amide bonds and that this perturbation is mediated by the primary sequence. To explain these data, we propose that a structural perturbation of the amide bond is driven by redox-linked electrostatic changes in the tyrosyl radical aromatic ring. 2013-11-22T20:38:31Z 2013-11-22T20:38:31Z 2009-05 2009-03 Article http://purl.org/eprint/type/JournalArticle 0002-7863 1520-5126 http://hdl.handle.net/1721.1/82563 Offenbacher, A. R., I. R. Vassiliev, M. R. Seyedsayamdost, J. Stubbe, and B. A. Barry. “Redox-Linked Structural Changes in Ribonucleotide Reductase.” Journal of the American Chemical Society 131, no. 22 (June 10, 2009): 7496-7497. https://orcid.org/0000-0001-8076-4489 en_US http://dx.doi.org/10.1021/ja901908j Journal of the American Chemical Society Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) PMC |
| spellingShingle | Offenbacher, Adam R. Vassiliev, I. R. Barry, Bridgette A. Stubbe, JoAnne Seyedsayamdost, Mohammad R. Redox-Linked Structural Changes in Ribonucleotide Reductase |
| title | Redox-Linked Structural Changes in Ribonucleotide Reductase |
| title_full | Redox-Linked Structural Changes in Ribonucleotide Reductase |
| title_fullStr | Redox-Linked Structural Changes in Ribonucleotide Reductase |
| title_full_unstemmed | Redox-Linked Structural Changes in Ribonucleotide Reductase |
| title_short | Redox-Linked Structural Changes in Ribonucleotide Reductase |
| title_sort | redox linked structural changes in ribonucleotide reductase |
| url | http://hdl.handle.net/1721.1/82563 https://orcid.org/0000-0001-8076-4489 |
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