Phosphatase and Pseudo-Phosphatase Functions of Phosphatase of Regenerating Liver 3 (PRL-3) Are Insensitive to Divalent Metals In Vitro

Phosphatase of regenerating liver 3 (PRL-3) is associatedwithcancer metastasis and has been shown to interact with the cyclin andCBS domain divalent metal cation transport mediator (CNNM) familyof proteins to regulate the intracellular concentration of magnesiumand other divalent metals. Despite PRL-3's importance in cancer,factors that regulate PRL-3's phosphatase activity and itsinteractions with CNNM proteins remain unknown. Here, we show thatdivalent metal ions, including magnesium, calcium, and manganese,have no impact on PRL-3's structure, stability, phosphataseactivity, or CNNM binding capacity, indicating that PRL-3 does notact as a metal sensor, despite its interaction with CNNM metal transporters.In vitro approaches found that PRL-3 is a broad but not indiscriminatephosphatase, with activity toward di- and tri-nucleotides, phosphoinositols,and NADPH but not other common metabolites. Although calcium, magnesium,manganese, and zinc-binding sites were predicted near the PRL-3 activesite, these divalent metals did not specifically alter PRL-3'sphosphatase activity toward a generic substrate, its transition froman inactive phospho-cysteine intermediate state, or its direct bindingwith the CBS domain of CNNM. PRL-3's insensitivity to metalcations negates the possibility of its role as an intracellular metalcontent sensor for regulating CNNM activity. Further investigationis warranted to define the regulatory mechanisms governing PRL-3'sphosphatase activity and CNNM interactions, as these findings couldhold potential therapeutic implications in cancer treatment.

Automated summary

Phosphatase of regenerating liver 3 (PRL-3) is associated with cancer metastasis and interacts with the CNNM family of proteins to regulate intracellular metal concentration. However, the factors that regulate PRL-3's activity and its interactions with CNNM proteins are unknown.