6og4 | pdb_00006og4
plasminogen binding group A streptococcal M protein
Structural highlights
Disease[PLMN_HUMAN] Defects in PLG are the cause of plasminogen deficiency (PLGD) [MIM:217090]. PLGD is characterized by decreased serum plasminogen activity. Two forms of the disorder are distinguished: type 1 deficiency is additionally characterized by decreased plasminogen antigen levels and clinical symptoms, whereas type 2 deficiency, also known as dysplasminogenemia, is characterized by normal, or slightly reduced antigen levels, and absence of clinical manifestations. Plasminogen deficiency type 1 results in markedly impaired extracellular fibrinolysis and chronic mucosal pseudomembranous lesions due to subepithelial fibrin deposition and inflammation. The most common clinical manifestation of type 1 deficiency is ligneous conjunctivitis in which pseudomembranes formation on the palpebral surfaces of the eye progresses to white, yellow-white, or red thick masses with a wood-like consistency that replace the normal mucosa.[1] [2] [3] [4] [5] [6] [7] [8] Function[PLMN_HUMAN] Plasmin dissolves the fibrin of blood clots and acts as a proteolytic factor in a variety of other processes including embryonic development, tissue remodeling, tumor invasion, and inflammation. In ovulation, weakens the walls of the Graafian follicle. It activates the urokinase-type plasminogen activator, collagenases and several complement zymogens, such as C1 and C5. Cleavage of fibronectin and laminin leads to cell detachment and apoptosis. Also cleaves fibrin, thrombospondin and von Willebrand factor. Its role in tissue remodeling and tumor invasion may be modulated by CSPG4. Binds to cells.[9] Angiostatin is an angiogenesis inhibitor that blocks neovascularization and growth of experimental primary and metastatic tumors in vivo.[10] [PAM_STRPY] Binds to human plasminogen (and plasmin) via its kringle repeats. Also binds to albumin, immunoglobulin G and fibrinogen. Could provide the bacteria with a mechanism for invasion, as streptococcal-bound plasmin could permit tissue penetration. Publication Abstract from PubMedPlasminogen (Plg)-binding M protein (PAM) is a group A streptococcal cell surface receptor that is crucial for bacterial virulence. Previous studies revealed that, by binding to the kringle 2 (KR2) domain of host Plg, the pathogen attains a proteolytic microenvironment on the cell surface that facilitates its dissemination from the primary infection site. Each of the PAM molecules in their dimeric assembly consists of two Plg binding motifs (called the a1 and a2 repeats). To date, the molecular interactions between the a1 repeat and KR2 have been structurally characterized, whereas the role of the a2 repeat is less well defined. Here, we report the 1.7-A x-ray crystal structure of KR2 in complex with a monomeric PAM peptide that contains both the a1 and a2 motifs. The structure reveals how the PAM peptide forms key interactions simultaneously with two KR2 via the high-affinity lysine isosteres within the a1a2 motifs. Further studies, through combined mutagenesis and functional characterization, show that a2 is a stronger KR2 binder than a1, suggesting that these two motifs may play discrete roles in mediating the final PAM-Plg assembly. Structure and Function Characterization of the a1a2 Motifs of Streptococcus pyogenes M Protein in Human Plasminogen Binding.,Quek AJH, Mazzitelli BA, Wu G, Leung EWW, Caradoc-Davies TT, Lloyd GJ, Jeevarajah D, Conroy PJ, Sanderson-Smith M, Yuan Y, Ayinuola YA, Castellino FJ, Whisstock JC, Law RHP J Mol Biol. 2019 Jul 8. pii: S0022-2836(19)30424-3. doi:, 10.1016/j.jmb.2019.07.003. PMID:31295457[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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