Phylogenetic and biochemical studies of Thermus thermophilus respiratory proteins relevant to aerobic heterotrophy at hydrothermal vents: the archaeal-type cytochrome ba3 from strain HB8 is a sulphide resistant cytochrome c oxidase
Fee, J.A.; Todaro, Th.R.; Sanders, D. (1998). Phylogenetic and biochemical studies of Thermus thermophilus respiratory proteins relevant to aerobic heterotrophy at hydrothermal vents: the archaeal-type cytochrome ba3 from strain HB8 is a sulphide resistant cytochrome c oxidase. Cah. Biol. Mar. 39(3-4): 351-354. https://dx.doi.org/10.21411/CBM.A.D99E41D1
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094
Also appears in:
(1998). Proceedings of the First International Symposium on Deep-Sea Hydrothermal Vent Biology: Funchal, Madeira, Portugal 20-24 October 1997. Cahiers de Biologie Marine, 39(3-4). Station Biologique de Roscoff: Roscoff. 219-392 pp., more
Our laboratory has been studying the respiratory proteins from Thermus thermophilus HB8 since the late 1970's, during which time we identified two cytochrome c oxidases. The cytochrome caa sub(3) was initially described in 1980 and has been subjected to extensive biochemical and biophysical characterization, including gene isolation and sequencing. It is derived from only two structural genes, one coding for a covalently linked subunit 1 and subunit 3 combination while the other gene codes for a protein consisting of a subunit 2 covalently linked with a cytochrome c. The cytochrome ba sub(3)dd was initially reported in 1988 and has also been subjected to considerable biophysical and biochemical characterization extending to gene isolation and sequencing. While our genetic work is not complete, two genes encoding for the two subunits of the as-isolated enzyme have been sequenced. In spite of being constructed from covalently linked proteins, cytochrome caa sub(3) appears to be closely related to other eubacterial cytochrome c oxidases. By contrast, cytochrome ba sub(3) is highly divergent in both sequence and chemical reactivity (see below), and the argument has been made that the genes encoding ba sub(3) were possibly acquired by Thermus by gene transfer (Keightley et al., 1995). A recent description of a cytochrome ba sub(3) from the archaebacterium, Natronobacterium pharaonis (Tindall et al., 1984) tends to support this contention (M. Engelhard, pers. comm.). In an effort to identify conditions under which expression of the two Thermus oxidases is optimized, we discovered that synthesis of cytochrome caa sub(3) is constitutive with respect to oxygen, whereas the synthesis of cytochrome ba sub(3) is greatly enhanced under microaerophilic growth conditions (see Fee et al., 1993; Keightley et al., 1995 for review and additional references). In this communication we report (a) that cytochrome ba sub(3) from the eubacterium T. thermophilus is a homologue with the archaebacterial cytochrome ba sub(3) from N. pharaonis, and (b) that the cytochrome ba sub(3) from T. thermophilus is highly resistant to sulphide inhibition, while the cytochrome caa sub(3) is strongly inhibited.
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