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Escherichia coli UshA and related proteins, N-terminal metallophosphatase domain. UshA is a bacterial periplasmic enzyme with UDP-sugar hydrolase and dinucleoside-polyphosphate hydrolase activities associated with its N-terminal metallophosphatase domain, and 5'-nucleotidase activity associated with its C-terminal domain. UshA has been studied in Escherichia coli where it is expressed from the ushA gene as an immature precursor and proteolytically cleaved to form a mature product upon export to the periplasm. UshA hydrolyzes many different nucleotides and nucleotide derivatives and has been shown to degrade external UDP-glucose to uridine, glucose 1-phosphate and phosphate for utilization by the cell. The N-terminal metallophosphatase domain belongs to a large superfamily of distantly related metallophosphatases (MPPs) that includes: Mre11/SbcD-like exonucleases, Dbr1-like RNA lariat debranching enzymes, YfcE-like phosphodiesterases, purple acid phosphatases (PAPs), YbbF-like UDP-2,3-diacylglucosamine hydrolases, and acid sphingomyelinases (ASMases). MPPs are functionally diverse, but all share a conserved domain with an active site consisting of two metal ions (usually manganese, iron, or zinc) coordinated with octahedral geometry by a cage of histidine, aspartate, and asparagine residues. The conserved domain is a double beta-sheet sandwich with a di-metal active site made up of residues located at the C-terminal side of the sheets. This domain is thought to allow for productive metal coordination. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",