Inactivation of the lysine binding sites of human plasminogen (hPg) reveals novel structural requirements for the tight hPg conformation, M-protein binding, and rapid activation

Copyright © 2023 Ayinuola and Castellino..

Accelerated activation of the human plasminogen zymogen (hPg) to two-chain active plasmin (hPm) is achieved following conformational changes induced by ligand-binding at the lysine-binding sites (LBSs) in four of the five hPg kringle domains. In this manner, pattern D skin-trophic strains of Group A streptococci (GAS), through the expression of surface plasminogen-binding M-protein (PAM), immobilize surface hPg, thereby enabling rapid hPg activation by GAS-secreted streptokinase (SK). Consequently, GAS enhances virulence by digesting extracellular and tight cellular junctional barriers using hPm activity. Many studies have demonstrated the singular importance of the kringle-2 domain of hPg (K2hPg) to PAM-binding using hPg fragments. Recently, we showed, using full-length hPg, that K2hPg is critical for PAM binding. However, these studies did not eliminate any modulatory effects of the non-K2hPg LBS on this interaction. Moreover, we sought to establish the significance of the intramolecular interaction between Asp219 of the LBS of K2hPg and its serine protease domain binding partner, Lys708, to conformational changes in hPg. In the current study, selective inactivation of the LBS of K1hPg, K4hPg, and K5hPg revealed that the LBS of these kringle domains are dispensable for hPg binding to PAM. However, the attendant conformational change upon inactivation of K4hPg LBS increased the affinity of hPg for PAM by an order of magnitude. This finding suggests that the native hPg conformation encloses PAM-binding exosites or sterically hinders access to K2hPg. While simultaneous inactivation of the LBS of K1hPg, K4hPg, and K5hPg inhibited hPg/SK association alongside hPg activation, the replacement of Lys708 generated a slight conformational change that optimally accelerated hPg activation. Thus, we accentuate disparate functions of hPg LBS and conclude, using intact proteins, that K2hPg plays a central role in regulating hPg activation.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:10

Enthalten in:

Frontiers in molecular biosciences - 10(2023) vom: 20., Seite 1166155

Sprache:

Englisch

Beteiligte Personen:

Ayinuola, Yetunde A [VerfasserIn]
Castellino, Francis J [VerfasserIn]

Links:

Volltext

Themen:

Bacterial M-protein
Journal Article
Plasminogen
Plasminogen activation
Protein mutagenesis
Streptococcal M-protein
Streptococcus pyogenes
Streptokinase

Anmerkungen:

Date Revised 22.04.2023

published: Electronic-eCollection

Citation Status PubMed-not-MEDLINE

doi:

10.3389/fmolb.2023.1166155

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM355856344