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Synechococcus sp. strain PCC 7942 PhoA and related proteins, N-terminal metallophosphatase domain Synechococcus sp. strain PCC 7942 PhoA is a large atypical alkaline phosphatase. It is known to be transported across the inner cytoplasmic membrane and into the periplasmic space. In vivo inactivation of the gene encoding PhoA leads to a loss of extracellular, phosphate-regulated phosphatase activity, but does not appear to affect the cells capacity for phosphate uptake. PhoA may play a role in scavenging phosphate during growth of Synechococcus sp. strain PCC 7942 in its natural environment. PhoA belongs to a domain family which includes the bacterial enzyme UshA and several other related enzymes including SoxB, CpdB, YhcR, and CD73. All members have a similar domain architecture which includes an N-terminal metallophosphatase domain and a C-terminal nucleotidase domain. 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.",