scholarly journals Structural basis of human γ-secretase assembly

2015 ◽  
Vol 112 (19) ◽  
pp. 6003-6008 ◽  
Author(s):  
Linfeng Sun ◽  
Lingyun Zhao ◽  
Guanghui Yang ◽  
Chuangye Yan ◽  
Rui Zhou ◽  
...  
Keyword(s):  
3D Structure ◽  
Structural Basis ◽  
Wild Type ◽  
Transmembrane Region ◽  
Electron Cryomicroscopy ◽  
Amino Terminal ◽  
Transmembrane Segments ◽  
Terminal Fragment ◽  
Carboxyl Terminal ◽  
Amino Terminal Fragment

The four-component intramembrane protease γ-secretase is intricately linked to the development of Alzheimer’s disease. Despite recent structural advances, the transmembrane segments (TMs) of γ-secretase remain to be specifically assigned. Here we report a 3D structure of human γ-secretase at 4.32-Å resolution, determined by single-particle, electron cryomicroscopy in the presence of digitonin and with a T4 lysozyme fused to the amino terminus of presenilin 1 (PS1). The overall structure of this human γ-secretase is very similar to that of wild-type γ-secretase determined in the presence of amphipols. The 20 TMs are unambiguously assigned to the four components, revealing principles of subunit assembly. Within the transmembrane region, PS1 is centrally located, with its amino-terminal fragment (NTF) packing against Pen-2 and its carboxyl-terminal fragment (CTF) interacting with Aph-1. The only TM of nicastrin associates with Aph-1 at the thick end of the TM horseshoe, and the extracellular domain of nicastrin directly binds Pen-2 at the thin end. TM6 and TM7 in PS1, which harbor the catalytic aspartate residues, are located on the convex side of the TM horseshoe. This structure serves as an important framework for understanding the function and mechanism of γ-secretase.

scholarly journals Evolution of the hedgehog Gene Family

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 965-972 ◽  
Author(s):  
Sudhir Kumar ◽  
Kristi A Balczarek ◽  
Zhi-Chun Lai
Keyword(s):  
Intercellular Communication ◽  
Short Range ◽  
Gene Duplications ◽  
Future Directions ◽  
Amino Terminal ◽  
Terminal Fragment ◽  
Carboxyl Terminal ◽  
Multicellular Organisms ◽  
Amino Terminal Fragment

Abstract Effective intercellular communication is an important feature in the development of multicellular organisms. Secreted hedgehog (hh) protein is essential for both long- and short-range cellular signaling required for body pattern formation in animals. In a molecular evolutionary study, we find that the vertebrate homologs of the Drosophila hh gene arose by two gene duplications: the first gave rise to Desert hh, whereas the second produced the Indian and Sonic hh genes. Both duplications occurred before the emergence of vertebrates and probably before the evolution of chordates. The amino-terminal fragment of the hh precursor, crucial in long- and short-range intercellular communication, evolves two to four times slower than the carboxyl-terminal fragment in both Drosophila hh and its vertebrate homologues, suggesting conservation of mechanism of hh action in animals. A majority of amino acid substitutions in the amino- and carboxyl-terminal fragments are conservative, but the carboxyl-terminal domain has undergone extensive insertion-deletion events while maintaining its autocleavage protease activity. Our results point to similarity of evolutionary constraints among sites of Drosophila and vertebrate hh homologs and suggest some future directions for understanding the role of hh genes in the evolution of developmental complexity in animals.

scholarly journals Highly Conserved C-Terminal Region of Indian Hedgehog N-Fragment Contributes to Its Auto-Processing and Multimer Formation

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 792
Author(s):  
Xiaoqing Wang ◽  
Hao Liu ◽  
Yanfang Liu ◽  
Gefei Han ◽  
Yushu Wang ◽  
...  
Keyword(s):  
Structure Prediction ◽  
3D Structure ◽  
Biochemical Properties ◽  
Terminal Region ◽  
Indian Hedgehog ◽  
Remarkable Effect ◽  
Amino Terminal ◽  
Terminal Fragment ◽  
C Terminus ◽  
Amino Terminal Fragment

Hedgehog (HH) is a highly conserved secretory signalling protein family mainly involved in embryonic development, homeostasis, and tumorigenesis. HH is generally synthesised as a precursor, which subsequently undergoes autoproteolytic cleavage to generate an amino-terminal fragment (HH-N), mediating signalling, and a carboxyl-terminal fragment (HH-C), catalysing the auto-processing reaction. The N-terminal region of HH-N is required for HH multimer formation to promote signal transduction, whilst the functions of the C-terminal region of HH-N remain ambiguous. This study focused on Indian Hedgehog (IHH), a member of the HH family, to explore the functions of the C-terminal region of the amino-terminal fragment of IHH (IHH-N) via protein truncation, cell-based assays, and 3D structure prediction. The results revealed that three amino acids, including S195, A196, and A197, were crucial for the multimer formation by inserting the mutual binding of IHH-N proteins. K191, S192, E193, and H194 had an extremely remarkable effect on IHH self-cleavage. In addition, A198, K199, and T200 evidently affected the stability of IHH-N. This work suggested that the C-terminus of IHH-N played an important role in the physiological function of IHH at multiple levels, thus deepening the understanding of HH biochemical properties.

The kringle stabilizes urokinase binding to the urokinase receptor

Blood ◽  
2003 ◽  
Vol 102 (10) ◽  
pp. 3600-3608 ◽  
Author(s):  
Khalil Bdeir ◽  
Alice Kuo ◽  
Bruce S. Sachais ◽  
Ann H. Rux ◽  
Yasmina Bdeir ◽  
...  
Keyword(s):  
Structural Basis ◽  
Heparin Binding ◽  
Wild Type ◽  
Single Chain ◽  
Amino Terminal ◽  
Charged Amino Acids ◽  
Heparin Binding Site ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Amino Terminal Fragment

AbstractThe structural basis of the interaction between single-chain urokinase-type plasminogen activator (scuPA) and its receptor (uPAR) is incompletely defined. Several observations indicated the kringle facilitates the binding of uPA to uPAR. A scuPA variant lacking the kringle (ΔK-scuPA) bound to soluble uPAR (suPAR) with the similar “on-rate” but with a faster “off-rate” than wild-type (WT)-scuPA. Binding of ΔK-scuPA, but not WT-scuPA, to suPAR was comparably inhibited by its growth factor domain (GFD) and amino-terminal fragment (ATF). ATF and WT-scuPA, but not GFD, scuPA lacking the GFD (ΔGFD-scuPA), or ΔK-scuPA reconstituted the isolated domains of uPAR. ATF completely inhibited the enzymatic activity of WT-scuPA-suPAR unlike comparable concentrations of GFD. Variants containing mutations that alter the charge, length, or flexibility of linker sequence (residues 43-49) between the GFD and the kringle displayed a lower affinity for uPAR, were unable to reconstitute uPAR domains, and their binding to uPAR was inhibited by GFD in the same manner as ΔK-scuPA. A scuPA variant in which the charged amino acids in the heparin binding site (HBS) in the kringle domain were mutated to alanines behaved like ΔK-scuPA, indicating that that the structure of the kringle as well as its interaction with the GFD govern receptor binding. These data demonstrate an important role for the kringle in stabilizing the binding of scuPA to uPAR. (Blood. 2003;102:3600-3608)

The amino‐terminal fragment of human urokinase directs a recombinant chimeric toxin to target cells: internalization is toxin mediated

1997 ◽  
Vol 11 (13) ◽  
pp. 1169-1176 ◽  
Author(s):  
M. Serena Fabbrini ◽  
Daniela Carpani ◽  
Iraldo Bello‐Rivero ◽  
Marco R. Soria
Keyword(s):  
Target Cells ◽  
Amino Terminal ◽  
Terminal Fragment ◽  
Amino Terminal Fragment

scholarly journals The Ubiquitin-associated Domain of hPLIC-2 Interacts with the Proteasome

2003 ◽  
Vol 14 (9) ◽  
pp. 3868-3875 ◽  
Author(s):  
Maurits F. Kleijnen ◽  
Rodolfo M. Alarcón ◽  
Peter M. Howley
Keyword(s):  
Proteasomal Degradation ◽  
Binding Domain ◽  
Full Length ◽  
Degradation Pathways ◽  
Wild Type ◽  
Amino Terminal ◽  
Uba Domain ◽  
Carboxyl Terminal ◽  
Protein Ligases

The ubiquitin-like hPLIC proteins can associate with proteasomes, and hPLIC overexpression can specifically interfere with ubiquitin-mediated proteolysis ( Kleijnen et al., 2000 ). Because the hPLIC proteins can also interact with certain E3 ubiquitin protein ligases, they may provide a link between the ubiquitination and proteasomal degradation machineries. The amino-terminal ubiquitin-like (ubl) domain is a proteasome-binding domain. Herein, we report that there is a second proteasome-binding domain in hPLIC-2: the carboxyl-terminal ubiquitin-associated (uba) domain. Coimmunoprecipitation experiments of wild-type and mutant hPLIC proteins revealed that the ubl and uba domains each contribute independently to hPLIC-2–proteasome binding. There is specificity for the interaction of the hPLIC-2 uba domain with proteasomes, because uba domains from several other proteins failed to bind proteasomes. Furthermore, the binding of uba domains to polyubiquitinated proteins does not seem to be sufficient for the proteasome binding. Finally, the uba domain is necessary for the ability of full-length hPLIC-2 to interfere with the ubiquitin-mediated proteolysis of p53. The PLIC uba domain has been reported to bind and affect the functions of proteins such as GABAAreceptor and presenilins. It is possible that the function of these proteins may be regulated or mediated through proteasomal degradation pathways.

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