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Evidence for a novel type of iron cluster in the respiratory chain of the archaeon Sulfolobus metallicus
Author(s) -
Gomes Cláudio M,
Huber Harald,
Stetter Karl O,
Teixeira Miguel
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00836-9
Subject(s) - respiratory chain , chemistry , reductase , electron paramagnetic resonance , cluster (spacecraft) , succinate dehydrogenase , biochemistry , enzyme , nuclear magnetic resonance , physics , computer science , programming language
A new type of metal centre was detected in the membranes of the thermoacidophilic archaeon Sulfolobus metallicus . This centre has an S =1/2 ground state in the oxidised form, yielding an axial EPR signal with g values at 2.035 ( g || ) and 1.97 ( g ⊥ ), optimally detected at 4.6–10 K; in the reduced form it is EPR silent (even spin). These magnetic properties point to a spin‐coupled iron cluster, with a minimum of two iron ions. The centre has a high reduction potential of +350 mV, at pH 6.5. The physiological role of this novel centre was probed through a general characterisation of S. metallicus respiratory chain: this archaeon contains NADH and succinate dehydrogenase activities, and cytochromes b 562 , a 586 and a 600 on the oxygen reductase system. Since it is reduced in the presence of succinate, and taking into account its high reduction potential, this centre is proposed to be a functional analogue of the Rieske centres.