Pneumococcal proteins ClpC and UvrC as novel host plasminogen binding factors

Abstract

Two plasminogen binding proteins were identified from a mouse infected with Streptococcus pneumoniae. The pneumococcal proteins were annotated as ATP‐dependent Clp protease ATP‐binding subunit (ClpC) and excinuclease ABC subunit C (UvrC) using the isobaric tags for relative and absolute quantification (iTRAQ) method. Recombinants of both proteins showed significant binding to plasminogen and were found to promote plasminogen activation by tissue‐type plasminogen activator. In addition, ClpC and UvrC were LytA‐dependently released into the culture supernatant and bound to the bacterial surface. These results suggest that S. pneumoniae releases ClpC and UvrC by autolysis and recruits them to the bacterial surface, where they bind to plasminogen and promote its activation, contributing to extracellular matrix degradation and tissue invasion.

C-Terminal Lysine Residue of Pneumococcal Triosephosphate Isomerase Contributes to Its Binding to Host Plasminogen

“…In S. pneumoniae , several proteins, including α-enolase [ 33 , 41 , 42 , 43 , 44 , 45 , 46 ], glyceraldehyde-3-phosphate dehydrogenase (GAPDH) [ 47 ], choline-binding protein E (CbpE) [ 48 ], plasminogen- and fibronectin-binding protein B [ 49 ], endopeptidase O (PepO) [ 50 ], elongation factor Tu (Tuf) [ 51 ], phosphate kinase [ 52 ], and PspC [ 53 ] have been reported to have plasminogen-binding properties. We recently discovered that the proteins triosephosphate isomerase (TpiA) [ 8 ], ClpC, and UvrC [ 18 ] also have plasminogen-binding properties. In particular, TpiA was shown not only to have high plasminogen-binding affinity but also to promote plasminogen activation.…”

“…Only 15 proteins were identified, many of which were endogenous molecules involved in metabolism. Among the proteins identified were α-enolase, GAPDH, Tuf, TpiA, ClpC, and UvrC, all of which have plasminogen-binding properties [ 8 , 18 ]. Although most of these proteins are intracellularly localized and do not have secretory or anchoring signals, they may perform other functions outside the cell or on the cell surface [ 54 , 55 ].…”

“…Plasminogen was activated to form plasmin using tPA according to a previously reported method [ 8 , 17 , 18 ], with some modifications, to investigate the effect of rTpiA proteins on plasminogen activation. All reagents and proteins were prepared in PBS (pH 7.4).…”

The Pneumococcal Protein SufC Binds to Host Plasminogen and Promotes Its Conversion into Plasmin

“…rGdhA and rRny were prepared according to a previously described method [17]. DNA fragments encoding GdhA and Rny (SPD_1158 and SPD_1549, respectively) were amplified from S. pneumoniae strain D39 genomic DNA via PCR using the primers listed in Table 1.…”

“…Although S. pneumoniae has 1911 protein-coding Microorganisms 2023, 11, 2969 2 of 14 genes [16], only 15 pneumococcal proteins in BALF could be detected using iTRAQ-based proteome analysis (<1% of the total pneumococcal proteins) [15]. Six of the fifteen pneumococcal proteins reportedly possess plasminogen-binding activity [17], whereas the functions of the other nine molecules in infections are unknown.…”