Effect of N-Terminal Myristoylation on the Active Conformation of Gα_i1–GTP

Abstract

G proteins are part of the G-protein-coupled receptor (GPCR) signal transduction cascade in which they transfer a signal from the membrane-embedded GPCR to other proteins in the cell. In the case of the inhibitory G-protein heterotrimer, permanent N-terminal myristoylation can transiently localize the Gα subunit at the membrane as well as crucially influence Gα's function in the GTP-bound conformation. The attachment of lipids to proteins is known to be essential for membrane trafficking; however, our results suggest that lipidation is also important for protein-protein interactions during signal transduction. Here we investigate the effect of myristoylation on the structure and dynamics of soluble Gα and its possible implication for signal transduction. A 2 μs classical molecular dynamics simulation of a myristoylated Gα-GTP complex suggests that the myristoyl-induced conformational changes of the switch II and alpha helical domains create new possibilities for protein-protein interactions and emphasize the importance of permanent lipid attachment for the conformation and functional tunability of signaling proteins.

Fumagillin, a Mycotoxin of Aspergillus fumigatus: Biosynthesis, Biological Activities, Detection, and Applications

“…Afterwards, these proteins activate intracellular signaling involved in numerous signal transduction pathways related to development, survival, proliferation, invasion, migration, tumorigenesis, etc. [31,[122][123][124][125]. Focusing on the activation of Gi/o, its α subunit can inhibit adenylyl cyclase (AC), incrementing ATP levels and inhibiting protein kinase A (PKA) [124].…”

Exploring the inhibition mechanism of adenylyl cyclase type 5 by n-terminal myristoylated Gαi1

“…Hence, it is not clear to what extent the missing N-terminal myristoyl moiety affects the Gα i structure of the remaining protein while the bound myristoyl group has been known to be crucial for Gα i ’s conformation and function as the ability to interact with AC5 is abolished upon removal of the myristate [ 4 – 6 ]. Classical molecular dynamics (MD) simulations of myristoylated GTP-bound Gα i1 , Gα i1 myr , demonstrate the stability of the myristoyl moiety on the Ras domain due to a hydrophobic pocket formed by β2-β3, α1 and the C-terminus α5 ( Fig 1C ) and show that myristoylation can have a significant effect on the conformation of the subunit [ 25 ]. The findings suggest the possibility of an alternative novel interaction mode and open up new possibilities for selective interactions with AC.…”

“…The findings suggest the possibility of an alternative novel interaction mode and open up new possibilities for selective interactions with AC. This is because the found structural changes in the classical MD simulations of Gα i1 myr [ 25 ] suggest that the subunit will not be able to interact with C1 as Gα s interacts with C2.…”

Regulation of adenylyl cyclase 5 in striatal neurons confers the ability to detect coincident neuromodulatory signals

“…The template used for the initial complex conformation included 1AZS's C1 and C2 domains (more specifically, canine AC5 for C1 and rat AC2 for C2) for modelling the AC5 structure (UniprotKB Q04400) from Rattus norvegicus as well as the Gα s ' structure for the initial Gα olf (UniprotKB P38406) conformation from Rattus norvegicus [20,58,59]. The modelled structure of the myristoylated Rattus norvegicus Gα i subunit (UniprotKB P10824) interacting with guanosine-5'-triphosphate (GTP) and Mg 2+ was taken from [56]. Gαi also has several isoforms, and the one referred to here is Gαi1.…”

“…The adjusted force field parameters for Cland K + were taken from [66]. The Mg 2+ parameters originated from [67] and the parameter set for the myristoyl group was taken from [56]. Electrostatic interactions were calculated with the Ewald particle mesh method with a real space cutoff of 12Å.…”