The crystal structure of dipeptidyl peptidase IV (CD26) reveals its functional regulation and enzymatic mechanism

Abstract

The membrane-bound glycoprotein dipeptidyl peptidase IV (DP IV, CD26) is a unique multifunctional protein, acting as receptor, binding and proteolytic molecule. We have determined the sequence and 1.8 Å crystal structure of native DP IV prepared from porcine kidney. The crystal structure reveals a 2-2-2 symmetric tetrameric assembly which depends on the natively glycosylated ␤-propeller blade IV. The crystal structure indicates that tetramerization of DP IV is a key mechanism to regulate its interaction with other components. Each subunit comprises two structural domains, the N-terminal eight-bladed ␤-propeller with open Velcro topology and the C-terminal ␣͞␤-hydrolase domain. Analogy with the structurally related POP and tricorn protease suggests that substrates access the buried active site through the ␤-propeller tunnel while products leave the active site through a separate side exit. A dipeptide mimicking inhibitor complexed to the active site discloses key determinants for substrate recognition, including a Glu-Glu motif that distinguishes DP IV as an aminopeptidase and an oxyanion trap that binds and activates the P 2-carbonyl oxygen necessary for efficient postproline cleavage. We discuss active and nonactive site-directed inhibition strategies of this pharmaceutical target protein.serine protease ͉ oxyanion hole ͉ substrate channeling ͉ drug design ͉ diabetes mellitus

The amino terminus extension in the long dipeptidyl peptidase 9 isoform contains a nuclear localization signal targeting the active peptidase to the nucleus

“…Biochemical examination reveals that similar to other members of the DPP family [6][7][8][9][10][11]42], DPP9-l also forms dimers and is active, with comparable cleavage characteristics to the shorter DPP9 variant. taken together, these results show for the first time that the endogenous pool of DPP9 protein in cells is composed of at least two different versions: DPP9-S and DPP9-l, which share similar biochemical properties.…”

“…Members of the S9B/DPPIV family are serine amino peptidases with the unique ability to cleave off N-terminal dipeptides from proteins/peptides having a proline residue at position 2 (X aa P). Four active members of this family are known so far: the two membrane-bound cell-surface members dipeptidyl peptidase IV (DPPIV) and the Fibroblast activation protein alpha (FaP), as well as the two soluble members DPP8 and 1 3 DPP9 (reviewed in [3][4][5][6]). Dimerization is a common feature for members of the S9B/DPPIV family [6][7][8][9][10][11] and is essential for enzymatic activity [12][13][14][15][16].…”

Solvent and thermal stability, and pH kinetics, of proline-specific dipeptidyl peptidase IV-like enzyme from bovine serum

“…DPP IV has broad substrate specificity for residues at the amino-terminal position (the P 2 position of Gly-Pro-AMC), although aliphatic residues are favoured and a protonated amino group at the P 2 position is a requirement [5,24,26,27]. The active site His residue must also be in the deprotonated form.…”

“…The active form of human DPP IV is a dimer; the monomer is inactive [24,26,27]. Assuming that the present bovine serum DPP IV-like peptidase also exists as a dimer, the biphasic loss of activity at 71°C may proceed via (i) formation of a partially-unfolded, but still catalytically active, dimeric intermediate and (ii) subsequent dissociation of the dimeric intermediate to inactive monomers.…”

Sulphostin, a Novel Inhibitor of Dipeptidyl Peptidases IV (DPPIV) That Stimulates Hematopoiesis in Mice

“…The complete c-DNA and derived amino acid sequence was published in 1992 [10] and the threedimensional crystal structure analysis was determined in 2003 [11]. CD26 is reported to be a marker of autoimmune disease, adenosine deaminase deficiency and HIV pathogenesis.…”