Catalytically Inactive SHP1-C453S Mutant Gain of “Robust LLPS” Function

SHP1 is a non-receptor protein tyrosine phosphatase extensively expressed in hematopoietic cells, exerting a pivotal role as an immunosuppressive factor. Our previous studies have suggested that SHP1 can undergo liquid-liquid phase separation (LLPS). In this study, the SHP1-C455S mutant, commonly utilized in biochemical assays due to its lack of catalytic phosphatase activity, unexpectedly exhibited a remarkably robust ability for LLPS. Since the C453S mutation has been previously shown to potentially induce a conformational transition of SHP1 from a closed to an open state, we hypothesize that the enhanced LLPS capability of SHP1 may be facilitated by this conformational alteration. The SHP1-C453S mutant exhibited robust LLPS activity, while completely abrogating its phosphatase activity. This allows for effective investigation of the catalytic activity and LLPS capability of SHP1.