TIGR04171, ribonucleotide-diphosphate_reductase_subunit_beta, ribonucleoside-diphosphate reductase, class 1b, beta subunit. Members of this family are NrdF, the beta subunit of class 1b ribonucleotide reductase. This form uses a dimanganese moiety associated with a tyrosine radical to reduce the cellular requirement for iron. [Purines, pyrimidines, nucleosides, and nucleotides, 2'-Deoxyribonucleotide metabolism].
cd01662, Ubiquinol_Oxidase_I, Ubiquinol oxidase subunit I. Ubiquinol oxidase, the terminal oxidase in the respiratory chains of aerobic bacteria, is a multi-chain transmembrane protein located in the cell membrane. It catalyzes the reduction of O2 and simultaneously pumps protons across the membrane. The number of subunits in ubiquinol oxidase varies from two to five. Subunit I contains a heme-copper binuclear center (the active site where O2 is reduced to water) formed by a high-spin heme and a copper ion. It also contains a low-spin heme, believed to participate in the transfer of electrons from ubiquinol to the binuclear center. For every reduction of an O2 molecule, eight protons are taken from the inside aqueous compartment and four electrons are taken from ubiquinol on the opposite side of the membrane. The four electrons and four of the protons are used in the reduction of O2; the four remaining protons are pumped across the membrane. This charge separation of four charges contributes to the electrochemical gradient used for ATP synthesis. Two proton channels, the D-pathway and K-pathway, leading to the binuclear center have been identified in subunit I. It is generally believed that the channels contain water molecules that act as 'proton wires' to transfer the protons. A well-defined pathway for the transfer of pumped protons beyond the binuclear center has not been identified. Electrons are believed to be transferred directly from ubiquinol (the electron donor) to the low-spin heme, and directly from the low-spin heme to the binuclear center.
cd07500, HAD_PSP, phosphoserine phosphatase (PSP), similar to Methanococcus Jannaschii PSP and Saccharomyces cerevisiae SER2p. This family includes Methanococcus jannaschii PSP, and Saccharomyces cerevisiae phosphoserine phosphatase SER2p, EC 3.1.3.3, which participates in a pathway whereby serine and glycine are synthesized from the glycolytic intermediate 3-phosphoglycerate; phosphoserine phosphatase catalyzes the hydrolysis of phospho-L-serine to L-serine and inorganic phosphate, the third reaction in this pathway. This family belongs to the haloacid dehalogenase-like (HAD) hydrolases, a large superfamily of diverse enzymes that catalyze carbon or phosphoryl group transfer reactions on a range of substrates, using an active site aspartate in nucleophilic catalysis. Members of this superfamily include 2-L-haloalkanoic acid dehalogenase, azetidine hydrolase, phosphonoacetaldehyde hydrolase, phosphoserine phosphatase, phosphomannomutase, P-type ATPases and many others. HAD hydrolases are found in all three kingdoms of life, and most genomes are predicted to contain multiple HAD-like proteins. Members possess a highly conserved alpha/beta core domain, and many also possess a small cap domain, the fold and function of which is variable. HAD hydrolases are sometimes referred to as belonging to the DDDD superfamily of phosphohydrolases.
pfam09438, DUF2017, Domain of unknown function (DUF2017). This is an alpha-helical domain found in gene neighborhoods that contain genes encoding ubiquitin, cysteine synthases and JAB peptidases.
pfam01694, Rhomboid, Rhomboid family. This family contains integral membrane proteins that are related to Drosophila rhomboid protein. Members of this family are found in bacteria and eukaryotes. Rhomboid promotes the cleavage of the membrane-anchored TGF-alpha-like growth factor Spitz, allowing it to activate the Drosophila EGF receptor. Analysis has shown that Rhomboid-1 is an intramembrane serine protease (EC:3.4.21.105). Parasite-encoded rhomboid enzymes are also important for invasion of host cells by Toxoplasma and the malaria parasite.
cd01055, Nonheme_Ferritin, nonheme-containing ferritins. Nonheme Ferritin domain, found in archaea and bacteria, is a member of a broad superfamily of ferritin-like diiron-carboxylate proteins. The ferritin protein shell is composed of 24 protein subunits arranged in 432 symmetry. Each protein subunit, a four-helix bundle with a fifth short terminal helix, contains a dinuclear ferroxidase center (H type). Unique to this group of proteins is a third metal site in the ferroxidase center. Iron storage involves the uptake of iron (II) at the protein shell, its oxidation by molecular oxygen at the ferroxidase centers, and the movement of iron (III) into the cavity for deposition as ferrihydrite.
cd07716, RNaseZ_short-form-like_MBL-fold, uncharacterized bacterial subgroup of Ribonuclease Z, short form; MBL-fold metallo-hydrolase domain. The tRNA maturase RNase Z (also known as tRNase Z or 3' tRNase) catalyzes the endonucleolytic removal of the 3' extension of the majority of tRNA precursors. Two forms of RNase Z exist in eukaryotes, one long (ELAC2) and one short form (ELAC1), the former may have resulted from a duplication of the shorter enzyme. Only the short form exists in bacteria. Members of this bacterial subgroup belong to the MBL-fold metallo-hydrolase superfamily which is comprised mainly of hydrolytic enzymes which carry out a variety of biological functions.
