PT  - JOURNAL ARTICLE
AU  - Shiqian Qi
AU  - Zichong Li
AU  - Ursula Schulze-Gahmen
AU  - Goran Stjepanovic
AU  - Qiang Zhou
AU  - James H. Hurley
TI  - How the AFF1/4 scaffold recruits the elongation factor ELL2 to promote HIV-1 proviral transcription
AID  - 10.1101/068262
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 068262
4099  - http://biorxiv.org/content/early/2016/08/06/068262.short
4100  - http://biorxiv.org/content/early/2016/08/06/068262.full
AB  - The intrinsically disordered scaffold proteins AFF1/4 and the transcription elongation factors ELL1/2 are core components of the superelongation complex required for HIV-1 proviral transcription. We determined the 2.0-Å resolution crystal structure of the human ELL2 C-terminal domain bound to its 50-residue binding site on AFF4, the ELLBow. The ELL2 domain has the same arch-shaped fold as the tight junction protein occludin. The ELLBow consists of an N-terminal helix followed by an extended hairpin that we refer to as the elbow joint, and occupies most of the concave surface of ELL2. This surface is important for the ability of ELL2 to promote HIV-1 Tat-mediated proviral transcription. The AFF4-ELL2 interface is imperfectly packed, leaving a cavity suggestive of a potential binding site for transcription-promoting small molecules.