TRX-like [2Fe-2S] Ferredoxin (Fd) family, NADH:ubiquinone oxidoreductase (Nuo) subunit E subfamily, hoxF; composed of proteins similar to the NAD-reducing hydrogenase (hoxS) alpha subunit of Alcaligenes eutrophus H16. HoxS is a cytoplasmic hydrogenase catalyzing the oxidation of molecular hydrogen accompanied by the reduction of NAD. It is composed of four structural subunits encoded by the genes hoxF, hoxU, hoxY and hoxH. The hoxF protein (or alpha subunit) is a fusion protein containing an N-terminal NuoE-like domain and a C-terminal NuoF domain. NuoE and NuoF are components of Nuo, a multisubunit complex catalyzing the electron transfer of NADH to quinone coupled with the transfer of protons across the membrane. Electrons are transferred from NADH to quinone through a chain of iron-sulfur clusters in Nuo, including the [2Fe-2S] cluster in NuoE and the [4Fe-4S] cluster in NuoF. In addition, NuoF is also the NADH- and FMN-binding subunit. HoxF may be involved in the electron transport chain during the NAD-dependent oxidation of hydrogen through its NuoF domain. The NuoE-like domain of hoxF contains only one conserved cysteine in its putative active site, compared to four cysteines in NuoE, and may have lost the ability to bind [2Fe-2S] clusters.
Jiyao W et al.(2023). "The conserved domain database in 2023.",