2WP9

Crystal structure of the E. coli succinate:quinone oxidoreductase (SQR) SdhB His207Thr mutant

Summary for 2WP9

• Entry DOI: 10.2210/pdb2wp9/pdb
• Related: 1NEK 1NEN 2ACZ 2WDQ 2WDR 2WDV 2WU2 2WU5
• Descriptor: SUCCINATE DEHYDROGENASE FLAVOPROTEIN SUBUNIT, FE3-S4 CLUSTER, PROTOPORPHYRIN IX CONTAINING FE, ... (13 entities in total)
• Functional Keywords: cell inner membrane, tricarboxylic acid cycle, metal-binding, transmembrane, flavoprotein, oxidoreductase, electron transport
• Biological source: ESCHERICHIA COLI; More
• Total number of polymer chains: 12
• Total formula weight: 363209.49

Authors

Ruprecht, J.,Yankovskaya, V.,Maklashina, E.,Iwata, S.,Cecchini, G. (deposition date: 2009-08-03, release date: 2010-08-25, Last modification date: 2024-11-13)

Primary citation

Ruprecht, J.,Iwata, S.,Rothery, R.A.,Weiner, J.H.,Maklashina, E.,Cecchini, G.
Perturbation of the quinone-binding site of complex II alters the electronic properties of the proximal [3Fe-4S] iron-sulfur cluster.
J. Biol. Chem., 286:12756-12765, 2011

PubMed Abstract: Succinate-ubiquinone oxidoreductase (SQR) and menaquinol-fumarate oxidoreductase (QFR) from Escherichia coli are members of the complex II family of enzymes. SQR and QFR catalyze similar reactions with quinones; however, SQR preferentially reacts with higher potential ubiquinones, and QFR preferentially reacts with lower potential naphthoquinones. Both enzymes have a single functional quinone-binding site proximal to a [3Fe-4S] iron-sulfur cluster. A difference between SQR and QFR is that the redox potential of the [3Fe-4S] cluster in SQR is 140 mV higher than that found in QFR. This may reflect the character of the different quinones with which the two enzymes preferentially react. To investigate how the environment around the [3Fe-4S] cluster affects its redox properties and catalysis with quinones, a conserved amino acid proximal to the cluster was mutated in both enzymes. It was found that substitution of SdhB His-207 by threonine (as found in QFR) resulted in a 70-mV lowering of the redox potential of the cluster as measured by EPR. The converse substitution in QFR raised the redox potential of the cluster. X-ray structural analysis suggests that placing a charged residue near the [3Fe-4S] cluster is a primary reason for the alteration in redox potential with the hydrogen bonding environment having a lesser effect. Steady state enzyme kinetic characterization of the mutant enzymes shows that the redox properties of the [3Fe-4S] cluster have only a minor effect on catalysis.

PubMed: 21310949
DOI: 10.1074/jbc.M110.209874

Experimental method

X-RAY DIFFRACTION (2.7 Å)