Structural basis for the growth factor activity of human adenosine deaminase ADA2.
Two distinct adenosine deaminases, ADA1 and ADA2, are found in humans. ADA1 has an important role in lymphocyte function and inherited mutations in ADA1 result in severe combined immunodeficiency. The recently isolated ADA2 belongs to the novel family of adenosine deaminase growth factors (ADGFs), which play an important role in tissue development. The crystal structures of ADA2 and ADA2 bound to a transition state analogue presented here reveal the structural basis of the catalytic/signaling activity of ADGF/ADA2 proteins. In addition to the catalytic domain, the structures discovered two ADGF/ADA2-specific domains of novel folds that mediate the protein dimerization and binding to the cell surface receptors. This complex architecture is in sharp contrast with that of monomeric single domain ADA1. An extensive glycosylation and the presence of a conserved disulfide bond and a signal peptide in ADA2 strongly suggest that ADA2, in contrast to ADA1, is specifically designed to act in the extracellular environment. The comparison of catalytic sites of ADA2 and ADA1 demonstrates large differences in the arrangement of the substrate-binding pockets. These structural differences explain the substrate and inhibitor specificity of adenosine deaminases and provide the basis for a rational design of ADA2-targeting drugs to modulate the immune system responses in pathophysiological conditions.
Department of Molecular Biology, Uppsala Biomedical Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Anton V
AV
Zavialov
Xiaodi
X
Yu
Dorothe
D
Spillmann
Grégoire
G
Lauvau
Andrey V
AV
Zavialov
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D000243:Adenosine Deaminase / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D020134:Catalytic Domain / Q000235:genetics; D003070:Coformycin / Q000494:pharmacology; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006133:Growth Substances / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D055672:Static Electricity; D013816:Thermodynamics; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D006133:Growth Substances; D011994:Recombinant Proteins; C097695:TADA2A protein, human; D014157:Transcription Factors; D003070:Coformycin; C548482:ADA protein, human; D000243:Adenosine Deaminase