PDBsum entry 1rjx

Hydrolase

PDB id: 1rjx

Contents

Protein chain

243 a.a. *

Ligands

SO4 ×8

Waters ×153

* Residue conservation analysis

PDB id:

1rjx

Name:

Hydrolase

Title:

Human plasminogen catalytic domain, k698m mutant

Structure:

Plasminogen. Chain: b. Fragment: serine protease catalytic domain. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Tissue: blood. Gene: plg. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Biol. unit:

Hexamer (from PQS)

Resolution:

2.30Å R-factor: 0.194 R-free: 0.245

Authors:

S.Terzyan,N.Wakeham,P.Zhai,K.Rodgers,X.C.Zhang

Key ref:

S.Terzyan et al. (2004). Characterization of Lys-698-to-Met substitution in human plasminogen catalytic domain. Proteins, 56, 277-284. PubMed id: 15211511 DOI: 10.1002/prot.20070

Date:

20-Nov-03 Release date: 02-Dec-03

Protein chain

P00747  (PLMN_HUMAN) -  Plasminogen from Homo sapiens

Seq: 810 a.a.

Struc: 243 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.4.21.7 - plasmin.
• Reaction: Preferential cleavage: Lys-|-Xaa > Arg-|-Xaa; higher selectivity than trypsin. Converts fibrin into soluble products.

DOI no: 10.1002/prot.20070

Proteins 56:277-284 (2004)

PubMed id: 15211511

Characterization of Lys-698-to-Met substitution in human plasminogen catalytic domain.

S.Terzyan, N.Wakeham, P.Zhai, K.Rodgers, X.C.Zhang.

ABSTRACT

Streptokinase (SK) is a human plasminogen (Pg) activator secreted by streptococci. The activation mechanism of SK differs from that of physiological Pg activators in that SK is not a protease and cannot proteolytically activate Pg. Instead, it forms a tight complex with Pg that proteolytically activates other Pg molecules. The residue Lys-698 of human Pg was hypothesized to participate in triggering activation in the SK-Pg complex. Here, we report a study of the Lys-698 to Met substitution in the catalytic domain of Pg (microPg) containing the proteolytic activation-resistant background (R561A). While it remains competent in forming a complex with SK, maintaining a comparable equilibration dissociation constant (K(D)), the recombinant protein shows a nearly 60-fold reduction in amidolytic activity relative to its R561A background when mixed with native SK. A 2.3 A crystal structure of this mutant microPg confirmed the correct folding of this recombinant protein. Combined with other biochemical data, these results support the premise that Lys-698 of human Pg plays a functional role in the so-called N-terminal insertion activation mechanism by SK.

Selected figure(s)

Figure 1.
Figure 1. Structural comparison of K698M mutant to other Pg ( Pm) crystal structures. In the middle, a ribbon diagram of K698M structure is shown in stereo view, flanked by diagrams of comparisons of local backbone traces. Fourteen previously published Pg ( Pm) crystal structures from six crystal forms are superimposed onto the K698M structure by overlaying their C[ ]atoms (using a 3-Å cutoff). The K698M structure (PDB file 1RJX) is colored in blue, Pm structures (1BML and 1BUI) in yellow, free Pg (1DDJ and 1QRZ) in green, and other Pg (1L4D and 1L4Z) in magenta. In the stereo diagram, positions of the K698M mutation and the catalytic Ser-741(195) are marked with yellow and green spheres, respectively.

The above figure is reprinted by permission from John Wiley & Sons, Inc.: Proteins (2004, 56, 277-284) copyright 2004.