bi5b01242_si_003.pdf (6.14 MB)
RhoGDIα Acetylation at K127 and K141 Affects Binding toward Nonprenylated RhoA
journal contribution
posted on 2016-01-19, 00:00 authored by Nora Kuhlmann, Sarah Wroblowski, Lukas Scislowski, Michael LammersRho proteins are major regulators
of the cytoskeleton. As most
Ras-related proteins, they switch between an active, GTP-bound and
an inactive, GDP-bound conformation. Rho proteins are targeted to
the plasma membrane via a polybasic region and a prenyl group attached
to a C-terminal cysteine residue. To distribute Rho proteins in the
cell, the molecular chaperone RhoGDIα binds to the prenylated
Rho proteins forming a cytosolic pool of mainly GDP-loaded Rho. Most
studies characterized the interaction of prenylated Rho proteins and
RhoGDIα. However, RhoGDIα was also shown to bind to nonprenylated
Rho proteins with physiologically relevant micomolar affinities. Recently,
it was discovered that RhoGDIα is targeted by post-translational
lysine acetylation. For one site, K141, it was hypothesized that acetylation
might lead to increased levels of formation of filamentous actin and
filopodia in mammalian cells. The functional consequences of lysine
acetylation for the interplay with nonprenylated RhoA have not been
investigated. Here, we report that lysine acetylation at lysines K127
and K141 in the RhoGDIα immunoglobulin domain interferes with
the interaction toward nonprenylated RhoA using a combined biochemical
and biophysical approach. We determined the first crystal structure
of a doubly acetylated protein, RhoGDIα, in complex with RhoA·GDP.
We discover that the C-terminus of RhoA adopts a different conformation
forming an intermolecular β-sheet with the RhoGDIα immunoglobulin
domain.