PDBsum entry 2qxj

Hydrolase

PDB id: 2qxj

Contents

Protein chain

224 a.a. *

Ligands

K7J

Metals

_CU ×2

Waters ×86

* Residue conservation analysis

PDB id:

2qxj

Name:

Hydrolase

Title:

Crystal structure of human kallikrein 7 in complex with suc-ala-ala- pro-phe-chloromethylketone and copper

Structure:

Kallikrein-7. Chain: a. Synonym: hk7, stratum corneum chymotryptic enzyme, hscce, serine protease 6. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: klk7, prss6, scce. Expressed in: spodoptera frugiperda. Expression_system_taxid: 7108.

Resolution:

2.10Å R-factor: 0.214 R-free: 0.248

Authors:

M.Debela,P.Hess,V.Magdolen,N.M.Schechter,W.Bode,P.Goettig

Key ref:

M.Debela et al. (2007). Chymotryptic specificity determinants in the 1.0 A structure of the zinc-inhibited human tissue kallikrein 7. Proc Natl Acad Sci U S A, 104, 16086-16091. PubMed id: 17909180 DOI: 10.1073/pnas.0707811104

Date:

11-Aug-07 Release date: 08-Jan-08

Protein chain

P49862  (KLK7_HUMAN) -  Kallikrein-7 from Homo sapiens

Seq: 253 a.a.

Struc: 224 a.a.

Enzyme reactions

• Enzyme class: E.C.3.4.21.117 - stratum corneum chymotryptic enzyme.

DOI no: 10.1073/pnas.0707811104

Proc Natl Acad Sci U S A 104:16086-16091 (2007)

PubMed id: 17909180

Chymotryptic specificity determinants in the 1.0 A structure of the zinc-inhibited human tissue kallikrein 7.

M.Debela, P.Hess, V.Magdolen, N.M.Schechter, T.Steiner, R.Huber, W.Bode, P.Goettig.

ABSTRACT

hK7 or human stratum corneum chymotryptic enzyme belongs to the human tissue kallikrein (hKs) serine proteinase family and is strongly expressed in the upper layers of the epidermis. It participates in skin desquamation but is also implicated in diverse skin diseases and is a potential biomarker of ovarian cancer. We have solved x-ray structures of recombinant active hK7 at medium and atomic resolution in the presence of the inhibitors succinyl-Ala-Ala-Pro-Phe-chloromethyl ketone and Ala-Ala-Phe-chloromethyl ketone. The most distinguishing features of hK7 are the short 70-80 loop and the unique S1 pocket, which prefers P1 Tyr residues, as shown by kinetic data. Similar to several other kallikreins, the enzyme activity is inhibited by Zn(2+) and Cu(2+) at low micromolar concentrations. Biochemical analyses of the mutants H99A and H41F confirm that only the metal-binding site at His(99) close to the catalytic triad accounts for the noncompetitive Zn(2+) inhibition type. Additionally, hK7 exhibits large positively charged surface patches, representing putative exosites for prime side substrate recognition.

Selected figure(s)

Figure 4.
Fig. 4. Stick model of the modeled substrate Glu-Ala-Leu-Tyr-Leu-Val, the catalytic triad and the backbone of Gly^193, Ser^195, and Gly^216 of hK7[I] in stereo, including hydrogen bonds as dotted lines. The S1 pocket is depicted as transparent green surface according to volume calculations with VOIDOO (41). The specificity for P1 Tyr is most likely conferred by Asn^189 via hydrogen bonds from the carboxamide side chain to an interconnecting water molecule and to the Tyr OH group, respectively.

Figure 5.
Fig. 5. The copper ions bound at His^99 and His^41 displayed as blue spheres surrounded by electron density of the anomalous Fourier map in red (contour 5 ) in stereo. His^57 has the capacity for liganding Cu1 and Cu2 by a side chain rotation (His57*), requiring shifts of the ions, whereas the mutant H99A proves that only the His^99 site is the structural basis for the Zn^2+ and Cu^2+ inhibition of hK7.

Figures were selected by an automated process.