PFN2 and NAA80 cooperate to efficiently acetylate the N-terminus of actin

The actin cytoskeleton is of profound importance to cell shape, division, and intracellular force generation. Profilins bind to globular (G-)actin and regulate actin filament formation. Although profilins are well-established actin regulators, the distinct roles of the dominant profilin, profilin 1 (PFN1), versus the less abundant profilin 2 (PFN2) remain enigmatic. Here, we define a specific role for PFN2 as a stable interactor and regulator of the actin N-terminal acetyltransferase NAA80. PFN2 binding increases the intrinsic catalytic activity of NAA80. Furthermore, binding of PFN2 to NAA80 via its proline-rich loop promotes binding between the globular domains of actin and NAA80, and thus acetylation of actin. The majority of NAA80 is stably bound to PFN2, and we propose that this complex acetylates G-actin before it is incorporated into filaments. In conclusion, we reveal a functionally specific role of PFN2, and establish the modus operandi for NAA80-mediated actin N-terminal acetylation. Data are available via ProteomeXchange with identifier PXD020188.