DNA hydrolysis by monoclonal anti-ssDNA autoantibody BV 04-01: origins of catalytic activity.
Monoclonal anti-DNA autoantibody BV 04-01 catalyzed hydrolysis of DNA in the presence of Mg2+ ions. DNA hydrolyzing activity was associated with BV 04-01 IgG, Fab, and SCA 04-01 proteins. Pronounced cleavage specificity for both ss and dsDNA was observed with efficient hydrolysis of the C-rich region of the oligonucleotide A7C7ATATAGCGCGT7 as well as preference for cleavage within CG-rich regions of double-stranded DNA. Data on specificity of ssDNA hydrolysis and kinetic data obtained from wild-type SCA 04-01 and two SCA 04-01 mutants (L32Phe and L27dHis) were used to model the catalytically active antibody site utilizing the previously resolved X-ray structure of (dT)3 liganded Fab 04-01. The resulting model suggested that BV 04-01 activates the target phosphodiester bond by induction of conformational strain. In addition, the antibody-DNA complex contained a potential Mg2+ ion coordination site composed of the L32Tyr and L27dHis amino acid side chains and a DNA 3'-phosphodiester group. Induction of strain and metal coordination could be constituents of a mechanism by which this antibody catalyzed DNA hydrolysis. Sequence data for BV 04-01 VH and VL genes suggested that the proposed catalytic antibody active site was germ-line encoded. This observation suggests the hypothesis that catalytic activity might represent an important but unspecified function of some antibody molecules.
Gololobov
G V
GV
Department of Pathology and Laboratory Medicine, University of Texas-Houston, Medical School, 77225-0708, USA.
Rumbley
C A
CA
Rumbley
J N
JN
Schourov
D V
DV
Makarevich
O I
OI
Gabibov
A G
AG
Voss
E W
EW
Rodkey
L S
LS
D000818:Animals; D017151:Antibodies, Catalytic / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000276:immunology*; D006868:Hydrolysis; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007700:Kinetics; D008958:Models, Molecular; D011487:Protein Conformation; D014407:Tumor Cells, Cultured
D017151:Antibodies, Catalytic; D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D004277:DNA, Single-Stranded; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D004247:DNA