Second Soluble Hox-Type NiFe Enzyme Completes the Hydrogenase Set in Thiocapsa roseopersicina BBS

• Published in: Applied and Environmental Microbiology Vol. 76; no. 15; pp. 5113 - 5123
• Main Authors: Maróti, Judit, Farkas, Attila, Nagy, Ildikó K, Maróti, Gergely, Kondorosi, Éva, Rákhely, Gábor, Kovács, Kornél L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.08.2010; American Society for Microbiology (ASM)
• Subjects: Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; Cytoplasm; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Enzyme kinetics; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Genomics; Glucose - metabolism; Hydrogen - metabolism; Hydrogenase - genetics; Hydrogenase - metabolism; Membranes; Microbiology; Molecular Sequence Data; Oxidation-Reduction; Physiology; Protein Multimerization; Sequence Analysis, DNA; Thiocapsa roseopersicina; Thiocapsa roseopersicina - enzymology; Thiosulfates - metabolism; Hydrogenase; Rhodospirillales; Thiocapsa roseopersicina; Enzyme; Thiocapsaceae; Bacteria; Oxidoreductases
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.00351-10

Three functional NiFe hydrogenases were previously characterized in Thiocapsa roseopersicina BBS: two of them are attached to the periplasmic membrane (HynSL and HupSL), and one is localized in the cytoplasm (HoxEFUYH). The ongoing genome sequencing project revealed the presence of genes coding for another soluble Hox-type hydrogenase enzyme (hox2FUYH). Hox2 is a heterotetrameric enzyme; no indication for an additional subunit was found. Detailed comparative in vivo and in vitro activity and expression analyses of HoxEFUYH (Hox1) and the newly discovered Hox2 enzyme were performed. Functional differences between the two soluble NiFe hydrogenases were disclosed. Hox1 seems to be connected to both sulfur metabolism and dark/photofermentative processes. The bidirectional Hox2 hydrogenase was shown to be metabolically active under specific conditions: it can evolve hydrogen in the presence of glucose at low sodium thiosulfate concentration. However, under nitrogen-fixing conditions, it can oxidize H₂ but less than the other hydrogenases in the cell.