Download MendeleyStructural analysis of human sterol transfer protein STARD4.
Tan, L., Tong, J., Chun, C., Im, Y.J.(2019) Biochem Biophys Res Commun 520: 466-472
- PubMed: 31607485
- DOI: https://doi.org/10.1016/j.bbrc.2019.10.054
- Primary Citation of Related Structures:
6L1D, 6L1M - PubMed Abstract:
The steroidogenic acute regulatory protein (StAR)-related lipid transfer domain-4 (STARD4) is a sterol-binding protein that is involved in cholesterol homeostasis by intracellular sterol transport. In this work, we determined the crystal structures of human STARD4 and its Ω1-loop mutant in apo forms at 1.95 and 1.7 Å resolutions, respectively. The structure of human STARD4 displays a conserved α-helix/β-grip fold containing a deep hydrophobic pocket. The Ω1-loop which serves as a lid for the hydrophobic pocket has a closed conformation. The shape of the sterol-binding cavity in the closed form is not complementary to accommodate cholesterol, suggesting that a conformational change of the Ω1-loop is essential for sterol binding. The human STARD4 displayed sterol transfer activity between liposomes, and the mutations in the Ω1-loop and the hydrophobic wall abolished the transfer activity. This study confirms the structural conservation of the STARD4 subfamily proteins and the flexibility of the Ω1-loop and helix α4 required for sterol transport.
Organizational Affiliation:
College of Pharmacy, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju, 61186, South Korea.
