The surface-displayed chaperones GroEL and DnaK of Mycoplasma pneumoniae interact with human plasminogen and components of the extracellular matrix

Abstract

Mycoplasma pneumoniae is a common cause of community-acquired infections of the human respiratory tract. The strongly reduced genome of the cell wall-less bacteria results in limited metabolic pathways and a small number of known virulence factors. In addition to the well-characterized adhesion apparatus and the expression of tissue-damaging substances, surface-exposed proteins with a primary function in cytosol-located processes such as glycolysis have been attracting attention in recent years. Due to interactions with host factors, it has been suggested that these bacterial proteins contribute to pathogenesis. Here, we investigated the chaperones GroEL and DnaK of M. pneumoniae as candidates for such moonlighting proteins. After successful expression in Escherichia coli and production of polyclonal antisera, the localization of both chaperones on the surface of bacteria was confirmed. Binding of recombinant GroEL and DnaK to human A549 cells, to plasminogen as well as to vitronectin, fibronectin, fibrinogen, lactoferrin and laminin was demonstrated. In the presence of both recombinant proteins and host activators, plasminogen can be activated to the protease plasmin, which is able to degrade vitronectin and fibrinogen. The results of the study extend the spectrum of surface-exposed proteins in M. pneumoniae and indicate an additional role of both chaperones in infection processes.

Characterization of an Immunoglobulin Binding Protein (IbpM) From Mycoplasma pneumoniae

“…Moreover, we show the binding of fibronectin and plasminogen to IbpM. For surface displayed proteins and lipoproteins in M. pneumoniae and other Mycoplasma species, the binding of plasminogen and fibronectin was already described (Yavlovich et al, 2004;Henderson et al, 2011;Gründel et al, 2016a,b;Hagemann et al, 2017;Chen et al, 2018;Qi et al, 2018). Neither fibronectin nor plasminogen binding was reported for components of the MIB-MIP system in M. mycoides.…”

“…Plasmin shares 48% amino acid similarity to serine proteases and is known to cleave IgG (Harpel et al, 1989;Chuba, 1994). In addition, the activation of plasminogen to plasmin, was already shown with different surface proteins of M. pneumoniae (Gründel et al, 2015;Hagemann et al, 2017). Moreover, binding of plasminogen and fibronectin for themselves could be important.…”

“…The reactivity of the blotted proteins was tested either with α-MPN400, α-Nox, and α-P14 (1:250 each). The NADH-oxidase (Nox; Pollack et al, 1997;Hagemann et al, 2017) and the C-terminal part of the main P1 adhesin (P14; Schurwanz et al, 2009) were used as cytosolic and surface-localized reference proteins, respectively.…”

Undervalued ubiquitous proteins

“…However, the interaction of DnaK and cancer is not just dependent on p53 dysregulation which reveals that focusing on signaling pathways in carcinogenesis is not enough. Mycoplasma infection induces MMP-1 and MMP-9 [145], 5-lipoxygenase (5-LOX, ALOX5, 15-LO-1, 15-LOX-1) and cyclooxygenase 2 (Cox-2) [146], cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) and interleukin 6 (IL-6) [147], plasmin [148], fibroblasts [149], p107 [150], IL-6, interleukin 1 beta (IL-1b), TGF-b and fibrosis [151], epidermal growth factor receptor (EGFR), phosphatidylinositide 3-kinase (PI3K), Akt, tumor suppressor phosphatase and tensin homolog (PTEN) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) [152][153][154], deacetylates forkhead box protein O3a (FOXO3a) [155], and downregulates E-cadherin [156].…”

Host-microbiome protein-protein interactions reveal mechanisms in human disease

“…A number of these proteins have been previously identified as 'moonlighting' proteins, which perform secondary functions in addition to their primary role in the cell 45 . Mycoplasma pneumoniae DnaK and enolase, a protein involved in glycolosis, from a number of pathogens, bind to both human plasminogen and extra-cellular matrix components 46,47 . Mycobacterium tuberculosis DnaK signals to leukocytes causing the release of the chemokines CCL3-5 48 .…”