Relationship between Structural Flexibility and Function in the C-Terminal Region of the Heparin-Binding Domain of VEGF165
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- 作者：Ki-Woong Jeong ; Min-Cheol Jeong ; Bonghwan Jin ; Yangmee Kim
- 刊名：Biochemistry
- 出版年：2013
- 出版时间：December 10, 2013
- 年：2013
- 卷：52
- 期：49
- 页码：8823-8832
- 全文大小：622K
- 年卷期：v.52,no.49(December 10, 2013)
- ISSN：1520-4995
文摘
Vascular endothelial growth factor (VEGF) is an angiogenic protein with neurotrophic and neuroprotective effects. Previously, we reported that triamterene (Trm) inhibits VEGF鈥揳myloid 尾 (A尾) interactions without affecting other biological activities of VEGF or A尾 [Jeong, K.-W., et al. (2011) Biochemistry 50, 4843鈥?854]. We further showed that molecular motions in the N-terminal disordered loop region of the heparin-binding domain (HBD) are important for interaction with Trm. To investigate the importance of motion at the C-terminal domain of HBD, we constructed a binding model of HBD with heparin octasaccharide (HOS) based on measurements of chemical shift changes and docking studies. Furthermore, the dynamic properties of the HBD鈥揌OS and HBD鈥揟rm鈥揌OS complexes were assessed by measuring spin relaxation rates. The results showed that the HOS-binding site is composed of two basic clusters consisting of side chains of residues R13, R14, and K15 and residues K30, R35, and R49. When HOS binds, values for the heteronuclear nuclear Overhauser effect near HOS-binding sites increased dramatically. CPMG (Carr鈥揚urcell鈥揗eiboom鈥揋ill sequence) experiments as well as an R2 relaxation experiment were undertaken to understand millisecond time-scale motions in HBD. There is large relaxation dispersion of residues at Trm- and HOS-binding sites in free HBD. C-Terminal residues such as S34, C48, and D51 near the HOS-binding sites continued to exhibit slow conformational motions in the HBD鈥揟rm complex, while those slow motions disappeared in the bound conformation of HBD with HOS. Collectively, our results demonstrate that the inherent structural flexibilities of the C-terminal region of the HBD are important in the heparin binding process and that Trm does not inhibit VEGF鈥揾eparin interactions necessary for the biological activities of VEGF.