3.1 Papers
3.1.6 Chronological list
3.1.6.66 Zhang, H-F., Yu, J., Chen, S., Morgan, B.P., Abagyan, R. and Tomlinson, S. (1999). Identification of the Individual Residues that Determine Human CD59 Species Selective Activity. J.Biol.Chem., 274, 10969-10974
Formation of the cytolytic membrane attack complex of complement on host cells is inhibited by the membrane-bound
glycoprotein, CD59. The inhibitory activity of CD59 is species restricted, and human CD59 is not effective against rat
complement. Previous functional analysis of chimeric human/rat CD59 proteins indicated that the residues responsible for
the species selective function of human CD59 map to a region contained between positions 40 and 66 in the primary
structure. By comparative analysis of rat and human CD59 models and by mutational analysis of candidate residues, we now
identify the individual residues within the 40-66 region that confer species selective function on human CD59. All
nonconserved residues within the 40-66 sequence were substituted from human to rat residues in a series of chimeric
human/rat CD59 mutant proteins. Functional analysis revealed that the individual human to rat residue substitutions F47A,
T51L, R55E, and K65Q each produced a mutant human CD59 protein with enhanced rat complement inhibitory activity
with the single F47A substitution having the most significant effect. Interestingly, the side chains of the residues at positions
47, 51, and 55 are all located on the short single helix (residues 47-55) of CD59 and form an exposed continuous strip
parallel to the helix axis. A single human CD59 mutant protein containing rat residue substitutions at all three helix residues
produced a protein with species selective activity comparable to that of rat CD59. We further found that synthetic peptides
spanning the human CD59 helix sequence were able to inhibit the binding of human CD59 to human C8, but had little effect
on the binding of rat CD59 to rat C8.
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