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Structure of apoptosis-linked protein ALG-2 : Insights into Ca2+-induced changes in penta-EF-hand proteins

Jia, Jia ; Tarabykina, Svetlana ; Hansen, Christian LU ; Berchtold, Martin and Cygler, Miroslaw (2001) In Structure 9(4). p.267-275
Abstract

Background: The Ca2+ binding apoptosis-linked gene-2 (ALG-2) protein acts as a proapoptotic factor in a variety of cell lines and is required either downstream or independently of caspases for apoptosis to occur. ALG-2 belongs to the penta-EF-hand (PEF) protein family and has two high-affinity and one low-affinity Ca2+ binding sites. Like other PEF proteins, its N terminus contains a Gly/Pro-rich segment. Ca2+ binding is required for the interaction with the target protein, ALG-2 interacting protein 1 (AIP1). Results: We present the 2.3 Å resolution crystal structure of Ca2+-loaded des1-20ALG-2 (aa 21-191), which was obtained by limited proteolysis of recombinant ALG-2 with elastase. The... (More)

Background: The Ca2+ binding apoptosis-linked gene-2 (ALG-2) protein acts as a proapoptotic factor in a variety of cell lines and is required either downstream or independently of caspases for apoptosis to occur. ALG-2 belongs to the penta-EF-hand (PEF) protein family and has two high-affinity and one low-affinity Ca2+ binding sites. Like other PEF proteins, its N terminus contains a Gly/Pro-rich segment. Ca2+ binding is required for the interaction with the target protein, ALG-2 interacting protein 1 (AIP1). Results: We present the 2.3 Å resolution crystal structure of Ca2+-loaded des1-20ALG-2 (aa 21-191), which was obtained by limited proteolysis of recombinant ALG-2 with elastase. The molecule contains eight α helices that fold into five EF-hands, and, similar to other members of this protein family, the molecule forms dimers. Ca2+ ions bind to EF1, EF3, and, surprisingly, to EF5. In the related proteins calpain and grancalcin, the EF5 does not bind Ca2+ and is thought to primarily facilitate dimerization. Most importantly, the conformation of des1-20ALG-2 is significantly different from that of calpain and grancalcin. This difference can be described as a rigid body rotation of EF1-2 relative to EF4-5 and the dimer interface, with a hinge within the EF3 loop. An electron density, which is interpreted as a hydrophobic Gly/Pro-rich decapeptide that is possibly derived from the cleaved N terminus, was found in a hydrophobic cleft between these two halves of the molecule. Conclusions: A different relative orientation of the N- and C-terminal halves of des1-20ALG-2 in the presence of Ca2+ and the peptide as compared to other Ca2+-loaded PEF proteins changes substantially the shape of the molecule, exposing a hydrophobic patch on the surface for peptide binding and a large cleft near the dimer interface. We postulate that the binding of a Gly/Pro-rich peptide in the presence of Ca2+ induces a conformational rearrangement in ALG-2, and that this mechanism is common to other PEF proteins.

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author
; ; ; and
publishing date
type
Contribution to journal
publication status
published
keywords
Calcium binding proteins, Calcium-induced changes, Penta EF-hand proteins
in
Structure
volume
9
issue
4
pages
9 pages
publisher
Cell Press
external identifiers
  • scopus:0034892270
  • pmid:11525164
ISSN
0969-2126
DOI
10.1016/S0969-2126(01)00585-8
language
English
LU publication?
no
id
bbf881f9-f780-408a-83c5-2dfc53614afb
date added to LUP
2018-09-11 14:50:27
date last changed
2024-04-01 10:13:13
@article{bbf881f9-f780-408a-83c5-2dfc53614afb,
  abstract     = {{<p>Background: The Ca<sup>2+</sup> binding apoptosis-linked gene-2 (ALG-2) protein acts as a proapoptotic factor in a variety of cell lines and is required either downstream or independently of caspases for apoptosis to occur. ALG-2 belongs to the penta-EF-hand (PEF) protein family and has two high-affinity and one low-affinity Ca<sup>2+</sup> binding sites. Like other PEF proteins, its N terminus contains a Gly/Pro-rich segment. Ca<sup>2+</sup> binding is required for the interaction with the target protein, ALG-2 interacting protein 1 (AIP1). Results: We present the 2.3 Å resolution crystal structure of Ca<sup>2+</sup>-loaded des1-20ALG-2 (aa 21-191), which was obtained by limited proteolysis of recombinant ALG-2 with elastase. The molecule contains eight α helices that fold into five EF-hands, and, similar to other members of this protein family, the molecule forms dimers. Ca<sup>2+</sup> ions bind to EF1, EF3, and, surprisingly, to EF5. In the related proteins calpain and grancalcin, the EF5 does not bind Ca<sup>2+</sup> and is thought to primarily facilitate dimerization. Most importantly, the conformation of des1-20ALG-2 is significantly different from that of calpain and grancalcin. This difference can be described as a rigid body rotation of EF1-2 relative to EF4-5 and the dimer interface, with a hinge within the EF3 loop. An electron density, which is interpreted as a hydrophobic Gly/Pro-rich decapeptide that is possibly derived from the cleaved N terminus, was found in a hydrophobic cleft between these two halves of the molecule. Conclusions: A different relative orientation of the N- and C-terminal halves of des1-20ALG-2 in the presence of Ca<sup>2+</sup> and the peptide as compared to other Ca<sup>2+</sup>-loaded PEF proteins changes substantially the shape of the molecule, exposing a hydrophobic patch on the surface for peptide binding and a large cleft near the dimer interface. We postulate that the binding of a Gly/Pro-rich peptide in the presence of Ca<sup>2+</sup> induces a conformational rearrangement in ALG-2, and that this mechanism is common to other PEF proteins.</p>}},
  author       = {{Jia, Jia and Tarabykina, Svetlana and Hansen, Christian and Berchtold, Martin and Cygler, Miroslaw}},
  issn         = {{0969-2126}},
  keywords     = {{Calcium binding proteins; Calcium-induced changes; Penta EF-hand proteins}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{4}},
  pages        = {{267--275}},
  publisher    = {{Cell Press}},
  series       = {{Structure}},
  title        = {{Structure of apoptosis-linked protein ALG-2 : Insights into Ca<sup>2+</sup>-induced changes in penta-EF-hand proteins}},
  url          = {{http://dx.doi.org/10.1016/S0969-2126(01)00585-8}},
  doi          = {{10.1016/S0969-2126(01)00585-8}},
  volume       = {{9}},
  year         = {{2001}},
}