S100A11 is a dimeric EF-hand calcium-binding protein. Calcium binding to S100A11 results in a large conformational change that uncovers a broad hydrophobic surface used to interact with phospholipid-binding proteins (annexins A1 and A2) and facilitate membrane vesiculation events. In contrast with other S100 proteins, S100A10 is unable to bind calcium due to deletion and substitution of calcium-ligating residues. Despite this, calcium-free S100A10 assumes an ‘open’ conformation that is very similar to S100A11 in its calcium-bound state. To understand how S100A10 is able to adopt an open conformation in the absence of calcium, seven chimaeric proteins were constructed where regions from calcium-binding sites I and II, and helices II–IV in S100A11 were replaced with the corresponding regions of S100A10. The chimaeric proteins having substitutions in calcium-binding site II displayed increased hydrophobic surface exposure as assessed by bis-ANS (4,4′-dianilino-1,1′-binaphthyl-5,5′disulfonic acid, dipotassium salt) fluorescence and phenyl-Sepharose binding in the absence of calcium. This response is similar to that observed for Ca2+–S100A11 and calcium-free S100A10. Further, this substitution resulted in calcium-insensitive binding to annexin A2 for one chimaeric protein. The results indicate that residues within site II are important in stabilizing the open conformation of S100A10 and presentation of its target binding site. In contrast, S100A11 chimaeric proteins with helical substitutions displayed poorer hydrophobic surface exposure and, consequently, unobservable annexin A2 binding. The present study represents a first attempt to systematically understand the molecular basis for the calcium-insensitive open conformation of S100A10.
Skip Nav Destination
Article navigation
February 2011
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkEditorial Board
Research Article|
January 27 2011
Identification of regions responsible for the open conformation of S100A10 using chimaeric S100A11–S100A10 proteins
Liliana Santamaria-Kisiel;
Liliana Santamaria-Kisiel
1Department of Biochemistry, University of Western Ontario, London, Ontario, Canada, N6A 5C1
Search for other works by this author on:
Gary S. Shaw
Gary S. Shaw
1
1Department of Biochemistry, University of Western Ontario, London, Ontario, Canada, N6A 5C1
1To whom correspondence should be addressed (email gshaw1@uwo.ca).
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
June 17 2010
Revision Received:
November 14 2010
Accepted:
November 25 2010
Accepted Manuscript online:
November 25 2010
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2011 Biochemical Society
2011
Biochem J (2011) 434 (1): 37–48.
Article history
Received:
June 17 2010
Revision Received:
November 14 2010
Accepted:
November 25 2010
Accepted Manuscript online:
November 25 2010
Citation
Liliana Santamaria-Kisiel, Gary S. Shaw; Identification of regions responsible for the open conformation of S100A10 using chimaeric S100A11–S100A10 proteins. Biochem J 15 February 2011; 434 (1): 37–48. doi: https://doi.org/10.1042/BJ20100887
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.