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Determinants of sulphur chemolithoautotrophy in the extremely thermoacidophilic Sulfolobales
Author(s) -
Zeldes Benjamin M.,
Loder Andrew J.,
Counts James A.,
Haque Mashkurul,
Widney Karl A.,
Keller Lisa M.,
Albers SonjaVerena,
Kelly Robert M.
Publication year - 2019
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.14712
Subject(s) - sulfolobus acidocaldarius , sulfur , biology , biochemistry , sulfolobus , heterologous expression , thermophile , reductase , archaea , enzyme , gene , chemistry , recombinant dna , organic chemistry
Summary Species in the archaeal order Sulfolobales thrive in hot acid and exhibit remarkable metabolic diversity. Some species are chemolithoautotrophic, obtaining energy through the oxidation of inorganic substrates, sulphur in particular, and acquiring carbon through the 3‐hydroxypropionate/4‐hydroxybutyrate (3‐HP/4‐HB) CO 2 ‐fixation cycle. The current model for sulphur oxidation in the Sulfolobales is based on the biochemical analysis of specific proteins from Acidianus ambivalens , including sulphur oxygenase reductase (SOR) that disproportionates S° into H 2 S and sulphite (SO 3 2− ). Initial studies indicated SOR catalyses the essential first step in oxidation of elemental sulphur, but an ancillary role for SOR as a ‘recycle’ enzyme has also been proposed. Here, heterologous expression of both SOR and membrane‐bound thiosulphate‐quinone oxidoreductase (TQO) from Sulfolobus tokodaii ‘restored’ sulphur oxidation capacity in Sulfolobus acidocaldarius DSM639, but not autotrophy, although earlier reports indicate this strain was once capable of chemolithoautotrophy. Comparative transcriptomic analyses of Acidianus brierleyi , a chemolithoautotrophic sulphur oxidizer, and S. acidocaldarius DSM639 showed that while both share a strong transcriptional response to elemental sulphur, S. acidocaldarius DSM639 failed to upregulate key 3‐HP/4‐HB cycle genes used by A. brierleyi to drive chemolithoautotrophy. Thus, the inability for S. acidocaldarius DSM639 to grow chemolithoautotrophically may be rooted more in gene regulation than the biochemical capacity.