Actin Filaments Are Involved in the Coupling of V-0-V-1 Domains of Vacuolar H+-ATPase at the Golgi Complex

作者：Serra Peinado Carla; Sicart Adria; Llopis Juan; Egea Gustavo^*

来源：Journal of Biological Chemistry, 2016, 291(14): 7286-7299.

DOI：10.1074/jbc.M115.675272

We previously reported that actin-depolymerizing agents promote the alkalization of the Golgi stack and the trans-Golgi network. The main determinant of acidic pH at the Golgi is the vacuolar-type H+-translocating ATPase (V-ATPase), whose V-1 domain subunits B and C bind actin. We have generated a GFP-tagged subunit B2 construct (GFP-B2) that is incorporated into the V-1 domain, which in turn is coupled to the V-0 sector. GFP-B2 subunit is enriched at distal Golgi compartments in HeLa cells. Subcellular fractionation, immunoprecipitation, and inversal FRAP experiments show that the actin depolymerization promotes the dissociation of V-1-V-0 domains, which entails subunit B2 translocation from Golgi membranes to the cytosol. Moreover, molecular interaction between subunits B2 and C1 and actin were detected. In addition, Golgi membrane lipid order disruption by D-ceramide-C6 causes Golgi pH alkalization. We conclude that actin regulates the Golgi pH homeostasis maintaining the coupling of V-1-V-0 domains of V-ATPase through the binding of microfilaments to subunits B and C and preserving the integrity of detergent-resistant membrane organization. These results establish the Golgi-associated V-ATPase activity as the molecular link between actin and the Golgi pH.

• 出版日期2016-4-1