Location of Repository

Engineering novel complement activity into a pulmonary surfactant protein

By Umakhanth Venkatraman Girija, Christopher M. Furze, Julia Toth, Wilhelm J. Schwaeble, Daniel A. Mitchell, Anthony H. Keeble and Russell Wallis


Complement neutralizes invading pathogens, stimulates inflammatory and adaptive immune responses, and targets non- or altered-self structures for clearance. In the classical and lectin activation pathways, it is initiated when complexes composed of separate recognition and activation subcomponents bind to a pathogen surface. Despite its apparent complexity, recognition-mediated activation has evolved independently in three separate protein families, C1q, mannose-binding lectins (MBLs), and serum ficolins. Although unrelated, all have bouquet-like architectures and associate with complement-specific serine proteases: MBLs and ficolins with MBL-associated serine protease-2 (MASP-2) and C1q with C1r and C1s. To examine the structural requirements for complement activation, we have created a number of novel recombinant rat MBLs in which the position and orientation of the MASP-binding sites have been changed. We have also engineered MASP binding into a pulmonary surfactant protein (SP-A), which has the same domain structure and architecture as MBL but lacks any intrinsic complement activity. The data reveal that complement activity is remarkably tolerant to changes in the size and orientation of the collagenous stalks of MBL, implying considerable rotational and conformational flexibility in unbound MBL. Furthermore, novel complement activity is introduced concurrently with MASP binding in SP-A but is uncontrolled and occurs even in the absence of a carbohydrate target. Thus, the active rather than the zymogen state is default in lectin·MASP complexes and must be inhibited through additional regions in circulating MBLs until triggered by pathogen recognition

Topics: QR180
Publisher: American Society for Biochemistry and Molecular Biology, Inc.
Year: 2010
OAI identifier: oai:wrap.warwick.ac.uk:3009

Suggested articles



  1. (1995). A novel serum protein similar to C1q, produced exclusively in adipocytes, doi
  2. (2009). Analogous interactions in initiating complexes of the classical and lectin pathways of complement, doi
  3. (1997). Asymmetry adjacent to the collagen-like domain in rat liver mannose-binding protein,
  4. (1976). Circular-dichroism and electron-microscopy studies of human subcomponent C1q before and after limited proteolysis by pepsin,
  5. (2009). Collagen structure and stability, doi
  6. (1994). Collectins - soluable proteins containing collagenous regions and lectin domains - and their roles in innate immunity, doi
  7. (1998). Complement component C1 and the collectins: parallels between routes of acquired and innate immunity, doi
  8. (2003). Crystal structure of the CUB1-EGF-CUB2 region of mannose-binding protein associated serine protease-2, doi
  9. (1999). EMILIN, a component of the elastic fiber and a new 8 member of the C1q/tumor necrosis factor superfamily of proteins, doi
  10. (2007). Identification of the site of human mannan-binding lectin involved in the interaction with its partner serine proteases: the essential role of Lys55, doi
  11. (2000). Impaired secretion of rat mannose-binding protein resulting from mutations in the collagen-like domain, doi
  12. (1991). Improved vectors for stable expression of foriegn genes in mammalian cells by use of the untranslated leader sequence from EMC virus, doi
  13. (1977). Inhibition of the reconstitution of the haemolytic activity of the first component of human complement by a pepsin-derived fragment of subcomponent C1q,
  14. (2007). Interactions between mannose-binding lectin and MASPs during complement activation by the lectin pathway, doi
  15. (2007). Localization and Characterization of the Mannose-Binding Lectin (MBL)-Associated-Serine Protease-2 Binding Site in Rat Ficolin-A: Equivalent Binding Sites within the Collagenous Domains of MBLs and Ficolins, doi
  16. (2004). Localization of the serine protease-binding sites in the collagen-like domain of mannosebinding protein: indirect effects of naturally occurring mutations on protease binding and activation, doi
  17. (2009). Mannan-Binding Lectin: Structure, Oligomerization, and Flexibility Studied by Atomic Force Microscopy, doi
  18. (1999). Molecular defects in variant forms of mannose-binding protein associated with immunodeficiency,
  19. (1999). Molecular determinants of oligomer formation and complement fixation in mannose-binding proteins, doi
  20. Paths reunited: Initiation of the classical and lectin pathways of complement activation, doi
  21. (2004). Proteases of the complement system, doi
  22. (1993). Role of the collagen-like domain of the human serum mannan-binding protein in the activation of complement and the secretion of this lectin, doi
  23. (2001). Stoichiometry of complexes between mannose-binding protein and its associated serine proteases. Defining functional units for complement activation, doi
  24. (2000). Structural basis of collagen recognition by integrin alpha2beta1, doi
  25. (2008). Structural basis of sequence-specific collagen recognition by SPARC, doi
  26. (1993). Studies on the carbohydrate-binding characteristics of human pulmonary surfactantassociated protein A and comparison with two other collectins: mannan-binding protein and conglutinin,
  27. (1976). Subunit composition and structure of subcomponent C1q of the first component of human complement,
  28. (2006). Surfactant protein A without the interruption of Gly-X-Y repeats loses a kink of oligomeric structure and exhibits impaired phospholipid liposome aggregation ability, doi
  29. (1978). The biochemistry of complement, doi
  30. (2004). Two mechanisms for mannose-binding protein modulation of the activity of its associated serine proteases, doi
  31. (1982). Ultrastructure of the first component of human complement: electron microscopy of the crosslinked complex, doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.