An engineered complement receptor 1 composed of two functional domains can protect against immune-mediated hemolysis.
Complement receptor type 1 (CR1) is a versatile inhibitor of both classical and alternative pathway C3 and C5 convertases with an ability to accelerate decay activity and act as a co-factor in C3b/C4b cleavage. In order to develop a short form of CR1 with similar biological activities to the full-length human CR1, we combined functional domain 1, located in the long homologous repeat (LHR) A, with functional domain 2, located in LHR C. We expressed the two-domain, two-function protein with an enterokinase site at the N-terminus and a termination codon at the C-terminus in Escherichia coli. The fusion protein was purified on a Ni-NTA-agarose column. After subsequent refolding, the recombinant CR1-derivative protein was obtained by enterokinase cleavage and subsequent purification. In vitro, the recombinant CR1-derivative reduced hemolysis, C5a release and surface C3 deposition. It was also effective in prolonging survival of transfused incompatible red blood cells in vivo. Our results indicate that the CR1-based protein may be a model for developing smaller and more potent complement inhibitors for future therapeutics.
Department of Microbiology, College of Medicine, The Third Military Medical University, Chongqing 400038, PR China.
Yongtao
Y
Yang
Li
L
He
Bing
B
Tan
Gaoke
G
Liu
Zhengqing
Z
Wang
D000818:Animals; D001787:Blood Group Incompatibility / Q000276:immunology; D003167:Complement Activation; D003179:Complement C3b / Q000276:immunology; D015936:Complement C5a / Q000276:immunology; D004765:Enteropeptidase / Q000378:metabolism; D006461:Hemolysis / Q000276:immunology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D011487:Protein Conformation; D015202:Protein Engineering; D011951:Receptors, Complement / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013879:Thioredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D011951:Receptors, Complement; D011993:Recombinant Fusion Proteins; D013879:Thioredoxins; D003179:Complement C3b; D015936:Complement C5a; D004765:Enteropeptidase