title: Molecular Determinants for the Binding Mode of Alkylphosphocholines in the C2 Domain of PKCα.
abstract: Alkylphosphocholines (APCs) and alkyl-lysophosphocholines (ALPs) are antineoplastic agents that interfere with cellular membranes and signaling proteins. Protein kinase Cα (PKCα) is a signaling protein composed by catalytic (C3, C4) and regulatory domains (C1, C2). The C2 needs calcium (Ca(2+) ) and phosphatidylserine (PS) for activation. Miltefosine inhibits PKCα competitively with regard to PS and non-competitively with regard to Ca(2+) , however, the mechanism of action is unknown. We employed molecular docking, molecular dynamics and chemometric methods to verify how 7 APCs and ALPs derivatives and PS interact with the C2 domain. All ligands except PS were grouped in 2 clusters according to their interactions inside the enzyme. The findings showed that PS's phosphoryl oxygens interact with Ca(2+) , the serine moiety interacts with Asn189, and the carbonyl oxygen of the alkylic chain interacts with Arg249 and Thr251. On the other hand, ligands' phosphoryl oxygens interact with Asn189, Arg249, Thr250, and one water molecule instead of Ca(2+) . Because of the different binding mode, we hypothesize that the ligands cause conformational changes in the calcium binding region. Moreover, the packing mismatch between bilayer-forming lipids and ALP/APC chain impedes the C2 domain from docking to the internal leaflet of cellular membranes, interrupting PKCα activation.
authors.affiliation: Department of Pharmacy, University of São Paulo, Avenida Professor Lineu Prestes, 580, 05508-900, São Paulo, SP, Brazil. matheus.de.sa@gmail.com, matheus.sa@usp.br.|Laboratório de Genética e Cardiologia Molecular, Instituto do Coração (InCor), Faculdade de Medicina da Universidade de São Paulo, Avenida Dr Eneas de Carvalho Aguiar, 44, 10th floor, 05403-000, São Paulo, SP, Brazil phone:+55 11 2661 5511. matheus.de.sa@gmail.com, matheus.sa@usp.br.
authors.forename: Matheus M
authors.initials: MM
authors.lastname: de Sá
authors.affiliation: Department of Pharmaceutical and Biochemical Technology, University of São Paulo, Avenida Professor Lineu Prestes, 580, 05508-900, São Paulo, SP, Brazil.
authors.forename: Carlota O
authors.initials: CO
authors.lastname: Rangel-Yagui
mesh_terms: D006801:Humans; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D010767:Phosphorylcholine / Q000737:chemistry*; D000072417:Protein Domains; D051571:Protein Kinase C-alpha / Q000737:chemistry*
chemical_list: D010767:Phosphorylcholine; C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha
keywords: Alkylphosphocholines; Docking; Molecular dynamics; Molecular modeling; Protein kinase C