TY - JOUR T1 - A PI(3,4,5)P3-dependent allosteric switch controls antigenic variation in trypanosomes JF - bioRxiv DO - 10.1101/2023.05.11.540368 SP - 2023.05.11.540368 AU - Abdoulie O. Touray AU - Rishi Rajesh AU - Tony Isebe AU - Tamara Sternlieb AU - Mira Loock AU - Oksana Kutova AU - Igor Cestari Y1 - 2023/01/01 UR - http://biorxiv.org/content/early/2023/05/11/2023.05.11.540368.abstract N2 - African trypanosomes evade host immune clearance by antigenic variation, causing persistent infections in humans and animals. These parasites express a homogeneous surface coat of variant surface glycoproteins (VSGs). They transcribe one out of hundreds of VSG genes at a time from telomeric expression sites (ESs) and periodically change the VSG expressed by transcriptional switching or recombination. The mechanisms underlying the control of VSG switching and its developmental silencing remain elusive. We report that telomeric ES activation and silencing entail an on/off genetic switch controlled by a nuclear phosphoinositide signaling system. This system includes a nuclear phosphatidylinositol 5-phosphatase (PIP5Pase), its substrate PI(3,4,5)P3, and the repressor-activator protein 1 (RAP1). RAP1 binds to ES sequences flanking VSG genes via its DNA binding domains and represses VSG transcription. In contrast, PI(3,4,5)P3 binds to the N-terminus of RAP1 and controls its DNA binding activity. Transient inactivation of PIP5Pase results in the accumulation of nuclear PI(3,4,5)P3, which binds RAP1 and displaces it from ESs, activating transcription of silent ESs and VSG switching. The system is also required for the developmental silencing of VSG genes. The data provides a mechanism controlling reversible telomere silencing essential for the periodic switching in VSG expression and its developmental regulation.Competing Interest StatementThe authors have declared no competing interest.PI(3,4,5)P3phosphatidylinositol-(3,4,5)-triphosphatePIP5Pasephosphatidylinositol phosphate 5-phosphataseRAP1repressor-activator protein 1ESexpression siteVSGvariant surface glycoproteins ER -