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Issue 12, 2019
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Model peptide for anti-sigma factor domain HHCC zinc fingers: high reactivity toward 1O2 leads to domain unfolding

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Abstract

All organisms have to cope with the deleterious effects of reactive oxygen species. Some of them are able to mount a transcriptional response to various oxidative stresses, which involves sensor proteins capable of assessing the redox status of the cell or to detect reactive oxygen species. In this article, we describe the design, synthesis and characterization of Zn·LASD(HHCC), a model for the Zn(Cys)2(His)2 zinc finger site of ChrR, a sensor protein involved in the bacterial defence against singlet oxygen that belongs to the family of zinc-binding anti-sigma factors possessing a characteristic H/C–X24/25–H–X3–C–X2–C motif. The 46-amino acid model peptide LASD(HHCC) was synthetized by solid phase peptide synthesis and its Zn2+-binding properties were investigated using electronic absorption, circular dichroism and NMR. LASD(HHCC) forms a 1 : 1 complex with Zn2+, namely Zn·LASD(HHCC), that adopts a well-defined conformation with the Zn2+ ion capping a 3-helix core that reproduces almost perfectly the fold of the ChrR in the vicinity of its zinc site. H2O2 reacts with Zn·LASD(HHCC) to yield a disulfide with a second order rate constant of 0.030 ± 0.002 M−1 s−1. Zn·LASD(HHCC) reacts rapidly with singlet oxygen to yield sulfinates and sulfonates. A lower limit of the chemical reaction rate constant between Zn·LASD(HHCC) and 1O2 was determined to be 3.9 × 106 M−1 s−1. Therefore, the Zn(Cys)2(His)2 site of Zn·LASD(HHCC) appears to be at least 5 times more reactive toward these two oxidants than that of a classical ββα zinc finger. Consequences for the activation mechanism of ChrR are discussed.

Graphical abstract: Model peptide for anti-sigma factor domain HHCC zinc fingers: high reactivity toward 1O2 leads to domain unfolding

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Supplementary files

Article information


Submitted
21 Jan 2019
Accepted
14 Feb 2019
First published
21 Feb 2019

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2019,10, 3608-3615
Article type
Edge Article

Model peptide for anti-sigma factor domain HHCC zinc fingers: high reactivity toward 1O2 leads to domain unfolding

V. Chabert, V. Lebrun, C. Lebrun, J. Latour and O. Sénèque, Chem. Sci., 2019, 10, 3608
DOI: 10.1039/C9SC00341J

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