A Residue outside the Binding Site Determines the G alpha Binding Specificity of GoLoco Motifs

作者：Liu, Chunhua; Weng, Jingwei; Wang, Dan; Yang, Maohua; Jia, Min; Wang, Wenning^*

来源：Biochemistry, 2018, 57(47): 6562-6569.

DOI：10.1021/acs.biochem.8b00848

• ASYMMETRIC CELL-DIVISION
• G-PROTEINS
• PINS
• LGN
• MECHANISM
• PARTNER
• REVEALS
• RELEASE
• NUMA

GoLoco motif-containing proteins regulate the nucleotide-binding state of G alpha proteins in various signaling pathways. As guanine nucleotide dissociation inhibitors (GDIs), they bind G alpha center dot GDP and inhibit GDP to GTP exchange. GoLoco proteins show binding selectivity toward different members of the Ga family. Although the G alpha(i1)center dot GDP/RGS14 crystal structure explains the specific binding selectivity of the RGS14 GoLoco domain well, the mechanism of selective binding has not been understood for the more general features of short GoLoco domains found in tandem arrays in proteins like GPSM2/LGN/dPins and GPSM1/AGS3. We explored the mechanism of differential interactions of GoLoco protein LGN with hG alpha(i3) and hG alpha(o). By combining mutagenesis experiments and molecular dynamics simulations, we identified a residue (Asp229 in hG alpha(i3)) away from the binding interface that remarkably affects the interaction between LGN and hGa(i/o). A negatively charged residue at this position is required for high binding affinity. This affinity regulation mechanism was further verified by the cases of hG alpha(i2) and dG alpha(o), suggesting that this pathway is conserved among members of the G alpha family.

• 出版日期2018-11-27
• 单位复旦大学