Salvador has an extended SARAH domain that mediates binding to Hippo kinase.

The Hippo pathway controls cell proliferation and differentiation through the precisely tuned activity of a core kinase cassette. The activity of Hippo kinase is modulated by interactions between its C-terminal coiled-coil, termed the domain, and the duanyu1800H domains of either dRassF or Salvador. Here, we wanted to understand the molecular basis of duanyu1800H domain-mediated interactions and their influence on Hippo kinase activity. We focused on Salvador, a positive effector of Hippo activity and the least well-characterized duanyu1800H domain-containing protein. We determined the crystal structure of a complex between Salvador and Hippo duanyu1800H domains from Drosophila This structure provided insight into the organization of the Salvador duanyu1800H domain including a folded N-terminal extension that expands the binding interface with Hippo duanyu1800H domain. We also found that this extension improves the solubility of the Salvador duanyu1800H domain, enhances binding to Hippo, and is unique to Salvador. We therefore suggest expanding the definition of the Salvador duanyu1800H domain to include this extended region. The heterodimeric assembly observed in the crystal was confirmed by cross-linked MS and provided a structural basis for the mutually exclusive interactions of Hippo with either dRassF or Salvador. Of note, Salvador influenced the kinase activity of Mst2, the mammalian Hippo homolog. In co-transfected HEK293T cells, human Salvador increased the levels of Mst2 autophosphorylation and Mst2-mediated phosphorylation of select substrates, whereas Salvador duanyu1800H domain inhibited Mst2 autophosphorylation in vitro These results suggest Salvador enhances the effects of Hippo kinase activity at multiple points in the Hippo pathway. © 2018 by The American Society for Biochemistry and Inc.

KEYWORDS: {{ getKeywords(articleDetailText.words) }}