Identification of a gene encoding a novel thiosulfate:quinone oxidoreductase in marine Acidithiobacillus sp. strain SH

• Published in: Research in microbiology 2020-10, Vol.171 (7), p.281-286
• Main Authors: Kanao, Tadayoshi, Sharmin, Sultana, Tokuhisa, Mirai, Otsuki, Maho, Kamimura, Kazuo
• Format: Article
• Language: English
• Subjects: Acidithiobacillus; Acidophile; Marine sulfur-oxidizer; Thiosulfate oxidation; Thiosulfate:quinone oxidoreductase
• ISSN: 0923-2508; 1769-7123
• DOI: 10.1016/j.resmic.2020.09.004

Sulfur-oxidizing bacteria that are halophilic and acidophilic have gained interest because of their potential use in bioleaching operations in salt-containing environments. Acidithiobacillus sp. strain SH, which was previously identified as Acidithiobacillus thiooxidans based on its 16S rRNA gene sequence, is a chemolithoautotrophic marine bacterium exhibiting sodium chloride-stimulated thiosulfate-oxidizing activities. A novel thiosulfate:quinone oxidoreductase from strain SH (SH-TQO) has been purified from its solubilized membrane fraction. The gene for SH-TQO was determined from the draft genome sequence of the strain SH. Amino acid sequences of peptides generated by the in-gel trypsin digestion of SH-TQO were found in a protein encoded by locus tag B1757_09800 of the genome of the strain SH. The gene encoded 444 amino acids with a signal peptide of 29 amino acids and was annotated to encode a porin. The gene was located in a unique genomic region, not found in A. thiooxidans strains, suggesting that the strain SH acquired this region through a horizontal gene transfer. A protein–protein basic local alignment search revealed that sulfur-oxidizing bacteria, such as Acidithiobacillus species have proteins homologous to SH-TQO, though the degree of homologies was relatively low. The protein, DoxXA, which is homologous to TQO from Acidianus amvibalens, was also found in the genomic region.