GTP binding controls complex formation by the human ROCO protein MASL1

The human ROCO proteins are a family of multi‐domain proteins sharing a conserved ROC ‐ COR supra‐domain. The family has four members: leucine‐rich repeat kinase 1 ( LRRK 1), leucine‐rich repeat kinase 2 ( LRRK 2), death‐associated protein kinase 1 ( DAPK 1) and malignant fibrous histiocytoma amplified sequences with leucine‐rich tandem repeats 1 ( MASL 1). Previous studies of LRRK 1/2 and DAPK 1 have shown that the ROC (Ras of complex proteins) domain can bind and hydrolyse GTP , but the cellular consequences of this activity are still unclear. Here, the first biochemical characterization of MASL 1 and the impact of GTP binding on MASL 1 complex formation are reported. The results demonstrate that MASL 1, similar to other ROCO proteins, can bind guanosine nucleotides via its ROC domain. Furthermore, MASL 1 exists in two distinct cellular complexes associated with heat shock protein 60, and the formation of a low molecular weight pool of MASL 1 is modulated by GTP binding. Finally, loss of GTP enhances MASL 1 toxicity in cells. Taken together, these data point to a central role for the ROC / GTP ase domain of MASL 1 in the regulation of its cellular function. Structured digital abstract HSP60 and MASL1 physically interact by molecular sieving ( View interaction ) MASL1 physically interacts with HSP70 and HSP60 by anti tag coimmunoprecipitation ( View interaction ) MASL1 physically interacts with HSP60 by anti tag coimmunoprecipitation ( View interaction )