Phosphatidylinositol 4-kinase IIIβ (PI4KB) forms highly flexible heterocomplexes that include ACBD3, 14-3-3, and Rab11 proteins

• Published in: Scientific reports Vol. 9; no. 1; p. 567
• Main Authors: Chalupska, Dominika, Różycki, Bartosz, Humpolickova, Jana, Faltova, Lenka, Klima, Martin, Boura, Evzen
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 24.01.2019; Nature Publishing Group UK
• Subjects: 1-Phosphatidylinositol 4-kinase; 14-3-3 protein; Golgi apparatus; Guanosine triphosphatases; Phosphatidylinositol 4-phosphate; Proteins; Stoichiometry; X-ray scattering
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-37158-6

Phosphatidylinositol 4-kinase IIIβ (PI4KB) is a key enzyme of the Golgi system because it produces its lipid hallmark - the phosphatidylinositol 4-phosphate (PI4P). It is recruited to Golgi by the Golgi resident ACBD3 protein, regulated by 14-3-3 proteins and it also serves as an adaptor because it recruits the small GTPase Rab11. Here, we analyzed the protein complexes formed by PI4KB in vitro using small angle x-ray scattering (SAXS) and we discovered that these protein complexes are highly flexible. The 14-3-3:PI4KB:Rab11 protein complex has 2:1:1 stoichiometry and its different conformations are rather compact, however, the ACBD3:PI4KB protein complex has both, very compact and very extended conformations. Furthermore, in vitro reconstitution revealed that the membrane is necessary for the formation of ACBD3:PI4KB:Rab11 protein complex at physiological (nanomolar) concentrations.