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Chemistry. 2016 Jul 4;22(28):9768-76. doi: 10.1002/chem.201600990. Epub 2016 Jun 1.

Crystal Structure Analysis of the Repair of Iron Centers Protein YtfE and Its Interaction with NO.

Author information

1
Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan.
2
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan. mmaestre@gate.sinica.edu.tw.
3
Department of Life Sciences, National Central University, Taoyuan, Taiwan. chinyuchen@cc.ncu.edu.tw.
4
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
5
Department of Chemistry, National Changhua University of Education, Changhua, Taiwan.
6
Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan. ywchiang@mx.nthu.edu.tw.
7
Department of Life Sciences, National Central University, Taoyuan, Taiwan.
8
National Synchrotron Radiation Research Center Hsinchu, Taiwan.
9
Department of Biotechnology, Yuanpei University, Hsinchu, Taiwan.
10
Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, H3A2K6, Canada. scott.bohle@mcgill.ca.
11
Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan. wfliaw@mx.nthu.edu.tw.

Abstract

Molecular mechanisms underlying the repair of nitrosylated [Fe-S] clusters by the microbial protein YtfE remain poorly understood. The X-ray crystal structure of YtfE, in combination with EPR, magnetic circular dichroism (MCD), UV, and (17) O-labeling electron spin echo envelope modulation measurements, show that each iron of the oxo-bridged Fe(II) -Fe(III) diiron core is coordinatively unsaturated with each iron bound to two bridging carboxylates and two terminal histidines in addition to an oxo-bridge. Structural analysis reveals that there are two solvent-accessible tunnels, both of which converge to the diiron center and are critical for capturing substrates. The reactivity of the reduced-form Fe(II) -Fe(II) YtfE toward nitric oxide demonstrates that the prerequisite for N2 O production requires the two iron sites to be nitrosylated simultaneously. Specifically, the nitrosylation of the two iron sites prior to their reductive coupling to produce N2 O is cooperative. This result suggests that, in addition to any repair of iron centers (RIC) activity, YtfE acts as an NO-trapping scavenger to promote the NO to N2 O transformation under low NO flux, which precedes nitrosative stress.

KEYWORDS:

nitric oxide; non-heme diiron; protein structures; proteins

PMID:
27246459
DOI:
10.1002/chem.201600990
[Indexed for MEDLINE]

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