RGD Reference Report - Engineering novel complement activity into a pulmonary surfactant protein. - Rat Genome Database

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Engineering novel complement activity into a pulmonary surfactant protein.

Authors: Venkatraman Girija, U  Furze, C  Toth, J  Schwaeble, WJ  Mitchell, DA  Keeble, AH  Wallis, R 
Citation: Venkatraman Girija U, etal., J Biol Chem. 2010 Apr 2;285(14):10546-52. doi: 10.1074/jbc.M109.097493. Epub 2010 Jan 29.
RGD ID: 7242176
Pubmed: PMID:20118239   (View Abstract at PubMed)
PMCID: PMC2856262   (View Article at PubMed Central)
DOI: DOI:10.1074/jbc.M109.097493   (Journal Full-text)

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.

Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
positive regulation of protein processing  IDA 7242176Masp2RGD 

Molecular Function

Objects Annotated

Genes (Rattus norvegicus)
Masp2  (MBL associated serine protease 2)
Mbl1  (mannose binding lectin 1)
Mbl2  (mannose binding lectin 2)

Objects referenced in this article
Gene Sftpa1 surfactant protein A1 Rattus norvegicus

Additional Information