Crystal structure of the caspase activator human granzyme B, a proteinase highly specific for an Asp-P1 residue.
Granzyme B is the prototypic member of the granzymes, a family of trypsin-like serine proteinases localized in the dense cytoplasmic granules of activated natural killer cells and cytotoxic T lymphocytes. Granzyme B directly triggers apoptosis in target cells by activating the caspase pathway, and has been implicated in the etiology of rheumatoid arthritis. Human granzyme B expressed in a baculovirus system has been crystallized without inhibitor and its structure has been determined to 3.1 A resolution, after considerably improving the diffraction power of the crystals by controlled humidity changes. The granzyme B structure reveals an overall fold similar to that found in cathepsin G and human chymase. The guanidinium group of Arg226, anchored at the back of the S1-specificity pocket, can form a salt bridge with the P1-Asp side chain of a bound peptide substrate. The architecture of the substrate binding site of granzyme B appears to be designed to accommodate and cleave hexapeptides such as the sequence Ile-Glu-Thr-Asp-/Ser-Gly present in the activation site of pro-caspase-3, a proven physiological substrate of granzyme B. These granzyme B crystals, with fully accessible active sites, are well suited for soaking with small synthetic inhibitors that might be used for a treatment of chronic inflammatory disorders.
Estébanez-Perpiña
E
E
Abteilung für Strukturforschung, Max-Planck-Institut für Biochemie, Planegg-Martinsried, Germany.
Fuentes-Prior
P
P
Belorgey
D
D
Braun
M
M
Kiefersauer
R
R
Maskos
K
K
Huber
R
R
Rubin
H
H
Bode
W
W
D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000737:chemistry / Q000378:metabolism*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D019281:Dimerization; D053804:Granzymes; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity
D001224:Aspartic Acid; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases