Identification of a lineage-specific protein network at the trypanosome nuclear envelope

The nuclear envelope (NE) separates translation and transcription and is the location of multiple functions, including chromatin organization, nucleocytoplasmic transport, ribosomal maturation and mRNA processing/quality control.  The molecular basis for many of these functions have diverged between different eukaryotic lineages.  Trypanosoma brucei, a member of the early branching eukaryotic lineage Discoba, highlight many of these, including a distinct lamina and kinetochore composition.  Here we describe a cohort of proteins interacting with both the lamina and NPC, which we term lamina-associated proteins (LAPs).  LAPs represent a diverse group of proteins, including two candidate NPC-anchoring pore membrane proteins (POMs) with architecture conserved with S. cerevisiae Pom152 and H. sapiens Nup210, and additional peripheral components of the NPC.  While many of the LAPs are specific to Trypanosomatids, we also identified broadly conserved proteins, indicating an amalgam of divergence and conservation within the NE proteome of trypanosomes, highlighting the diversity of nuclear biology across the eukaryotes and increasing our understanding of eukaryotic and NPC evolution.