3.4.23.48	evolution	comparative analysis of the sequences of the pro-omptin Pla with other omptin family proteases, such as PgtE from Salmonella enterica (EC 3.4.23.49), SopA from Shigella flexneri, and OmpT and OmpP from Escherichia coli reveals the location of predicted linear B-cell epitopes in either identical positions or in a very close proximity to all nine Pla epitopes predicted from library, and identified serologically using human anti-Pla antisera, overview	
3.4.23.48	evolution	the enzyme belongs to the omptin family of enzymes	
3.4.23.48	evolution	the modern isoform of Pla (T259) with an increased protease activity is found in Yersinia pestis subsp. pestis strains that are highly virulent for humans. The pathogenicity factor is absent in representatives of the Yersinia pestis subsp. microtus bv. caucasica/SNP-type 0.PE2, while an ancestral Pla isoform (I259) with characteristics similar to the properties of omptins from less virulent enterobacteria is found in three representatives of Yersinia pestis subsp. microtus (SNP-types 0.PE3 and 0.PE4), which are, as a rule, avirulent to guinea pigs and humans. Distribution of Pla isoforms among natural isolates of Yersinia pestis of different origin, overview	
3.4.23.48	evolution	the pathogenicity factor is absent in representatives of the Yersinia pestis subsp. microtus bv. caucasica/SNP-type 0.PE2, while an ancestral Pla isoform (I259) with characteristics similar to the properties of omptins from less virulent enterobacteria is found in three representatives of Yersinia pestis subsp. microtus (SNP-types 0.PE3 and 0.PE4), which are, as a rule, avirulent to guinea pigs and humans. The modern isoform of Pla (T259) with an increased protease activity is found in Yersinia pestis subsp. pestis strains that are highly virulent for humans. Sequencing of pla genes from 118 Yersinia pestis subsp. microtus isolates reveals the absence of this gene in the strains belonging to bv. caucasica. All remaining isolates of Yersinia pestis subsp. microtus contain the ancestral Pla isoform (I259). Distribution of Pla isoforms among natural isolates of Yersinia pestis of different origin, overview	
3.4.23.48	malfunction	eliminating Pla expression in a fully virulent Yersinia pestis strain decreases its LD50 by 6 orders of magnitude in a mouse model of bubonic plague	
3.4.23.48	malfunction	Pla deficient Yersinia pestis disseminate to regional lymph nodes after subcutaneous inoculation but do not cause the lymphadenopathy observed with wild-type Yersinia pestis infections	
3.4.23.48	malfunction	survival of mice infected with Pla-deficient Yersinia pestis is greater than cohorts infected with wild-type Yersinia Pestis. Survival advantage is negated, if fibrinogen knockout mice are infected instead, directly implicating the host coagulation system as a target for Pla's role in virulence	
3.4.23.48	malfunction	deletion of Pla results in a decreased Yersinia pestis bacterial burden in the host lung and failure to progress into the lethal proinflammatory phase of disease. Deletion of Pla does not alter adherence to and/or secretion into THP-1 cells. Infection of human precision-cut lung slices (hPCLS) with the knockout DELTApla strain results in significantly reduced Yersinia outer protein (Yop) translocation early after infection and continuing to 4 hours-post-infection. And deletion of Pla results in decreased Yersinia pestis T3S into alveolar macrophages in vivo during pneumonic plague. Addition of Pla to Yersinia pestis lacking all five known adhesins partially restores adherence and Yop delivery to macrophages derived from the human monocytic cell line THP-1 and human epithelial type 2 (HEp-2) cells, suggesting that Pla may contribute to adherence and Yop translocation in vitro	
3.4.23.48	malfunction	introducing the single point mutation D206A into the active site of Pla suffices to render fully virulent Yersinia pestis susceptible to primed T-cells	
3.4.23.48	metabolism	plasminogen is an abundant circulating zymogen of the serine protease plasmin, which is the key enzyme in fibrinolysis. The physiological plasminogen activation by uPA (EC 3.4.21.73) or tPA (EC 3.4.21.68) is a single cut at the peptide bond R560-V561, which yields the two-chain active plasmin enzyme. Pla rapidly cleaves the same peptide as do the human physiological activators, and the formed plasmin remains enzymatically active as Pla does not degrade the B chain of plasmin that contains the protease catalytic domain	
3.4.23.48	additional information	the primary action of Pla is to protect bacteria from destruction rather than to alter the tissue environment to favor Yersinia pestis propagation in the host. Analysis of intraspecies distribution, intrinsic disorder propensity, and contribution to virulence of the two isoforms of Yersinia pestis plasminogen activator Pla, overview. Survival curves of the endemic I259 Pla+ strains are similar to the parent Pla-negative variants, but significant difference in mean time to death post infection between the Pla- strains and their I259 Pla+ variants can be seen only in the isogenic set of Yersinia pestis subsp. pestis strains. An essential role for the outer membrane protease Pla evolution in Yersinia pestis bubonic infection exacerbation is suggested that is necessary for intensification of epidemic process from endemic natural focality with sporadic cases in humans to rapidly expanding epizootics followed by human epidemic outbreaks, local epidemics or even pandemics. Pla expression is associated with a marked ability to colonize the viscera and thus cause lethal infection upon administration by peripheral routes of infection, such as intradermal or subcutaneous. The Pla activity is not required to initiate lethal disease by intravenous injection, which provides immediate access to fixed macrophages lining the capillary beds of the liver and spleen. Virulence study of Yersinia pestis expressing different isoforms of Pla in a bubonic plague model	
3.4.23.48	additional information	the primary action of Pla is to protect bacteria from destruction rather than to alter the tissue environment to favor Yersinia pestis propagation in the host. Analysis of intraspecies distribution, intrinsic disorder propensity, and contribution to virulence of the two isoforms of Yersinia pestis plasminogen activator Pla, overview. Survival curves of the endemic I259 Pla+ strains are similar to the parent Pla-negative variants, but significant difference in mean time to death post infection between the Pla- strains and their I259 Pla+ variants can be seen only in the isogenic set of Yersinia pestis subsp. pestis strains. Pla expression is associated with a marked ability to colonize the viscera and thus cause lethal infection upon administration by peripheral routes of infection, such as intradermal or subcutaneous. The Pla activity is not required to initiate lethal disease by intravenous injection, which provides immediate access to fixed macrophages lining the capillary beds of the liver and spleen. Virulence study of Yersinia pestis expressing different isoforms of Pla in a bubonic plague model	
3.4.23.48	physiological function	1. Pla expression results in attenuated inflammatory cell recruitment (particularly neutrophils) to infected lesions 2. Pla expression causes a structural derangement of infected lymph tissue characterized by lymphadenitis, necrosis, hemorrhage, thrombosis, and disorganized masses of infiltrating bacteria. 3. Pla expression promotes the systemic dissemination of the infection	
3.4.23.48	physiological function	Pla works to accelerate the initiation phase of blood clotting by activating the first enzyme in blood clotting (factor VIIa) and inactivating its most important protease inhibitor in plasma (TFPI). This is highly reminiscent of the ability of Pla to activate plasminogen to plasmin and to inactivate its plasma inhibitor, alpha2-antiplasmin	
3.4.23.48	physiological function	the outer membrane plasminogen activator Pla of Yersinia pestis is a central virulence factor in plague	
3.4.23.48	physiological function	Yersinia pestis binding to fibronectin is mediated through Ail protein and plasminogen activator Pla	
3.4.23.48	physiological function	cleavage of Yersinia pestis autotransporter YapE by protease Pla is required to mediate bacterial aggregation and adherence to eukaryotic cells. Post-translation modification of YapE appears to be specific to Yersinia pestis. It was acquired along with the acquisition ofplasmid pPCP1 during the divergence of Yersinia pestis from Yersinia pseudotuberculosis, and is the first evidence of a mechanism to regulate bacterial adherence	
3.4.23.48	physiological function	the plasminogen activator Pla single and the Braun lipoprotein Lpp Pla double mutant are unable to survive efficiently in murine and human macrophages. The levels of Pla and its associated protease activity are not affected in the Lpp single mutant, and, likewise, deletion of the Pla gene from wild-type does not alter Lpp levels. The ability of the Lpp Pla double mutant to be phagocytized by macrophages, to stimulate production of tumor necrosis factor-alpha and interleukin-6, and to activate the nitric oxide killing pathways of the host cells remains unaltered when compared to the wild-type-infected macrophages. Macrophages infected with either the wild-type or the Lpp Pla double mutant are equally efficient in their uptake of zymosan particles	
3.4.23.48	physiological function	Pla of the enteropathogen Yersinia pestis is a surface-exposed, transmembrane beta-barrel proteases of the omptin family that exhibit a complex array of interactions with the hemostatic systems in vitro, the protease is an established virulence factor. Pla favors fibrinolysis by direct activation of plasminogen, inactivation of the serpins plasminogen activator inhibitor-1 and alpha2-antiplasmin, inactivation of the thrombin-activable fibrinolysis inhibitor, and activation of single-chain urokinase. Inactivation of alpha2AP enables proteolysis by the Pla-generated plasmin. The enzymatic activity of the protease is strongly influenced by the environment-induced variations in lipopolysaccharide that binds to the beta-barrel. The protease cleaves the tissue factor pathway inhibitor and thus also expresses procoagulant activity. Some of the functions observed for Pla, such as adhesiveness to laminin and invasiveness into human cells as well as efficient plasmin generation are not shown by PgtE (EC 3.4.23.49) or OmpT. Pla is adapted to support efficient plasminogen activation in the bubonic plague and to enhance bacterial survival in the lungs	
3.4.23.48	physiological function	plasminogen activator inhibitor-1 (PAI-1) is an in vivo target of the Pla protease in the lungs during pneumonic plague. PAI-1 is a key regulator of the pulmonary innate immune response and contributes to the regulation of cytokine production and promotion of neutrophil recruitment during Yerisnia pestis respiratory infection. The inactivation of PAI-1 by Yersinia pestis alters the host environment to promote virulence. PAI-1 restricts the proliferation of Yersinia pestis in the absence of enzyme Pla	
3.4.23.48	physiological function	the activity of the plasminogen activator protease Pla is the key to the progression of infection of Yersinia pestis in humans. Enzyme Pla facilitates type 3 secretion into primary alveolar macrophages but not into the commonly used THP-1 cell line. Analysis of the role of Pla in promoting optimal type 3 secretion using primary human tissue with relevant host cell heterogeneity in human precision-cut lung slices, a model of living tissue. Pla is a key player in the early host/pathogen interactions and a key virulence factor. Pla plays a role in adherence to alveolar macrophages that may not be detected using immortalized cell lines	
3.4.23.48	physiological function	the plasminogen activator Pla is a protease that promotes fibrin degradation and prevents T cell-mediated defense against fully virulent Yersinia pestis. Pla functions to thwart fibrin-dependent T-cell-mediated defense against plague by promoting fibrinolysis. The presence of primed CD8 T-cells can suffice to protect against a lethal dose (LD) of a virulent Yersinia pestis strain rendered deficient in Pla activity in a fibrin-dependent manner