Integration of the reverse-transcribed viral cDNA into the host's genome is a critical step in the lifecycle of all retroviruses. Retrovirus integration is carried out by integrase (IN), a virus-encoded enzyme that forms an oligomeric 'intasome' complex with both ends of the linear viral DNA to catalyze their concerted insertions into the backbones of the host's DNA. IN also forms a complex with host proteins, which guides the intasome to the host's chromosome. Recent structural studies have revealed remarkable diversity as well as conserved features among the architectures of the intasome assembly from different genera of retroviruses. This chapter will review how IN oligomerizes to achieve its function, with particular focus on alpharetrovirus including the avian retrovirus Rous sarcoma virus. Another chapter (Craigie) will focus on the structure and function of IN from HIV-1.
Keywords: Alpharetrovirus; Avian sarcoma/leukemia (ASLV); Betaretrovirus; Bromodomain and extra-terminal (BET).; C-terminal domain (CTD); Catalytic core domain (CCD); Concerted integration; Conserved intasome core (CIC); Cryo electron microscopy (EM); Crystal structure; D,D(35)E motif; FAcilitates Chromatin Transcription (FACT); Human immunodeficiency virus type 1 (HIV-1); Intasome; Integrase (IN); Lens epithelium-derived growth factor (LEDGF/p75); Lentivirus; Mouse mammary tumor virus (MMTV); N-terminal domain (NTD); Preintegration complex (PIC); Prototype foamy virus (PFV); Retrovirus; Rous sarcoma virus (RSV); Spumavirus; Stable synaptic complex (SSC); Strand transfer complex (STC); Strand transfer inhibitor (STI).