Protease Excretion Research Articles

Harmine acts as a quorum sensing inhibitor decreasing the virulence and antibiotic resistance of Pseudomonas aeruginosa

BackgroundAs antimicrobial resistance (AMR) has become a global health crisis, new strategies against AMR infection are urgently needed. Quorum sensing (QS), responsible for bacterial communication and pathogenicity, is among the targets for anti-virulence drugs that thrive as one of the promising treatments against AMR infection.MethodsWe identified a natural compound, Harmine, through virtual screening based on three QS receptors of Pseudomonas aeruginosa (P. aeruginosa) and explored the effect of Harmine on QS-controlled and pathogenicity-related phenotypes including pyocyanin production, exocellular protease excretion, biofilm formation, and twitching motility of P. aeruginosa PA14. The protective effect of Harmine on Caenorhabditis elegans (C. elegans) and mice infection models was determined and the synergistic effect of Harmine combined with common antibiotics was explored. The underlaying mechanism of Harmine’s QS inhibitory effect was illustrated by molecular docking analysis, transcriptomic analysis, and target verification assay.ResultsIn vitro results suggested that Harmine possessed QS inhibitory effects on pyocyanin production, exocellular protease excretion, biofilm formation, and twitching motility of P. aeruginosa PA14, and in vivo results displayed Harmine’s protective effect on C. elegans and mice infection models. Intriguingly, Harmine increased susceptibility of both PA14 and clinical isolates of P. aeruginosa to polymyxin B and kanamycin when used in combination. Moreover, Harmine down-regulated a series of QS controlled genes associated with pathogenicity and the underlying mechanism may have involved competitively antagonizing autoinducers’ receptors LasR, RhlR, and PqsR.ConclusionsThis study shed light on the anti-virulence potential of Harmine against QS targets, suggesting the possible use of Harmine and its derivates as anti-virulence compounds.

Protease Profile of Tumor-Associated Mast Cells in Melanoma.

Mast cells (MCs) produce a variety of mediators, including proteases—tryptase, chymase, and carboxypeptidases—which are important for the immune response. However, a detailed assessment of the mechanisms of biogenesis and excretion of proteases in melanoma has yet to be carried out. In this study, we present data on phenotype and secretory pathways of proteases in MCs in the course of melanoma. The development of melanoma was found to be accompanied by the appearance in the tumor-associated MC population of several pools with a predominant content of one or two specific proteases with a low content or complete absence of others. Elucidation of the molecular and morphological features of the expression of MC proteases in melanoma allows us a fresh perspective of the pathogenesis of the disease, and can be used to clarify MCs classification, the disease prognosis, and evaluate the effectiveness of ongoing antitumor therapy.

Abstract MP44: Proteolytic Activation Of ENaC Mediates Fructose-Induced Salt-Sensitive Hypertension

In nephrotic syndrome, glomerular injury leads to filtration of plasma proteases. Once in the urine, these enzymes cleave and activate the epithelial Na channel (ENaC) causing inappropriate Na retention and hypertension. Dietary fructose causes inappropriate Na retention and salt-sensitive hypertension but whether proteolytic activation of ENaC is involved, and the source of the proteases, is unknown. We hypothesized that dietary fructose increases expression and release of proteases from the proximal nephron, and that these enzymes activate ENaC thereby causing Na retention and salt-sensitive hypertension. To test this hypothesis we first measured proximal nephron protease expression and urinary protease excretion in rats on either a high-salt diet without fructose (high salt) or one containing 4% NaCl plus 20% fructose in the drinking water (high salt/fructose) for 7 days. High salt/fructose treatment increased proximal nephron expression of trypsin I, an enzyme known to cleave and activate ENaC, by 68±7% (p < 0.01). Urinary excretion of trypsin I was 8.4±1.3 arbitrary units/μg protein in rats fed high salt while it was 20.3±4.6 arbitrary units/μg protein in those on the high salt/fructose diet, 142% greater (p < 0.02). There was no difference in total urinary protein excretion between groups. Finally, we examined the effect of high salt/fructose and high salt plus 20% glucose) high salt/glucose) on blood pressure before and after oral amiloride. After 7 days the systolic blood pressure of rats on high salt/fructose was 148±6 mm Hg while it was only 124±5 in those on high salt/glucose (p < 0.02). Amiloride reduced systolic blood pressure in rats on the high salt/fructose diet from 148±6 to 134±5 mm Hg but had no significant effect on the high salt/glucose group. We conclude that proteolytic cleavage of ENaC contributes to fructose-induced salt-sensitive hypertension and that the source of the protease(s) is likely the proximal tubule rather than glomerular filtration.

Proteolytic Activation of ENaC Mediates Fructose‐Induced Salt‐Sensitive Hypertension

Proteolytic cleavage of the amiloride‐sensitive epithelial sodium channel (ENaC) by serine proteases such as trypsin leads to channel activation. In nephrotic syndrome, glomerular injury allows filtration of such enzymes causing ENaC‐dependent Na retention and hypertension(PMID: 23216619). Dietary fructose also causes Na retention and salt‐sensitive hypertension at least, in part, via altered hormonal signaling and metabolism in the proximal nephron. Proximal tubules normally secrete proteases into the forming urine but whether they are a source of proteases that cleave and activate ENaC in fructose‐induced salt‐sensitive hypertension is unknown. We hypothesized that dietary fructose increases expression and release of proteases from the proximal nephron, and that these enzymes activate ENaC thereby causing Na retention and salt‐sensitive hypertension. To test this hypothesis we first measured proximal nephron protease expression and urinary protease excretion in rats on either a high‐salt diet containing 4% NaCl without fructose (high salt) or one containing high salt plus 20% fructose in the drinking water (high salt/fructose) for 7 days. High salt/fructose treatment increased proximal nephron expression of trypsin I, an enzyme known to cleave and activate ENaC, by 70% (p < 0.01) compared to high salt alone. Urinary excretion of trypsin I was 8.4±1.3 arbitrary units/μg protein in rats fed high salt while it was 20.3±4.6 arbitrary units/μg protein in those on the high salt/fructose diet, 142% greater (p < 0.02). There was no difference in total urinary protein excretion between groups. Finally, we examined the effect of high salt/fructose and high salt plus 20% glucose (high salt/glucose) on blood pressure before and after oral amiloride. After 7 days, the systolic blood pressure of rats on high salt/fructose was 142±6 mm Hg while it was only 121±6 mm Hg in those on high salt/glucose (p < 0.05). After 10 days, the systolic blood pressure of rats on high salt/fructose was 148±6 mm Hg while it was only 124±5 in those on high salt/glucose (p < 0.02). Amiloride treatment for 24 hrs reduced systolic blood pressure in rats on the high salt/fructose diet from 148±6 to 134±5 mm Hg but did not decrease it in the high salt/glucose group. We conclude that proteolytic cleavage of ENaC contributes to fructose‐induced salt‐sensitive hypertension and that the source of the protease(s) is likely the proximal tubule rather than glomerular filtration.Support or Funding InformationNLHBI HL128053

Characterization of halo-alkaline and thermostable protease from Halorubrum ezzemoulense strain ETR14 isolated from Sfax solar saltern in Tunisia.

A total of 54 halophilic strains were isolated from crystallizer TS18 (26 strains) and non-crystallizer M1 (28 strains) ponds and screened for their ability to produce protease, amylase, and lipase activities. Enzymatic assays allowed the selection of thirty-two active strains, among them, the ETR14 strain from TS18 showed maximum protease production yields and therefore, selected for further analysis. The results from 16S rRNA gene sequence analysis revealed that the strain belonged to Halorubrum ezzemoulense (Hrr. ezzemoulense) species. Further results indicated that optimum growth and protease production yields were obtained with 10-15% NaCl concentrations in the DSC-97 medium. The enzyme was also able to maintain high levels of protease activity at salt concentrations of up to 25%. While readily available carbon sources were noted to significantly reduce protease production, the combination between yeast extract and peptone enhanced protease excretion, which reached a maximum of 284 U ml(-1) at the end of the exponential growth phase. The enzyme exhibited optimum activity at pH 9 and 60 °C. The halophilic protease retained 87% of its initial activity after 1 h incubation at 70 °C and showed high stability over a wide range of pH, ranging from 7 to 10. This protease exhibited good temperature, pH, and salinity tolerance, which distinguishes it from other proteases previously described from other members of the holoarchaea genera and makes it a promising candidate for application in various industries.

Integrated criteria to identify the best treatment in plant biotechnology experiments

Plant scientists usually record many indicators in their experiments. The common statistical management involves univariate analyses. Such analyses generally create a split picture of the effects of experimental treatments since each indicator is addressed independently. The Euclidean distance combined with the expert’s criteria seems to show potential as an integrating indicator. The Euclidean distance has been widely used in many scientific fields nevertheless, as far as we know, it has not been frequently employed in plant science experiments. To exemplify the use of the Euclidean distance in this field, we performed an experiment focused on the effects of gibberellic acid on protease excretion during pineapple micropropagation in temporary immersion bioreactors. Five gibberellic acid concentrations were compared: 0.0, 1.4, 2.8, 4.2 and 5.6 μM. Four dependent variables were recorded: increase in fresh shoot mass, protein concentration, proteolytic activity and specific activity in the culture media. The statistical protocol carried out integrated these four dependent variables to easily identify the best gibberellic acid treatment. Based on expert’s criteria the integral analysis provided by the Euclidean distance indicated that 4.2 μM gibberellic acid is the best treatment to produce proteases in the experimental conditions described here. This treatment showed the shortest (statistically significant) Euclidean distance to expert’s criteria (0.61).

Induction of protease release of the resistant diatom Chaetoceros didymus in response to lytic enzymes from an algicidal bacterium.

Marine lytic bacteria can have a substantial effect on phytoplankton and are even capable to terminate blooms of microalgae. The bacterium Kordia algicida was reported to lyse cells of the diatom Skeletonema costatum and several other diatoms by a quorum sensing controlled excretion of proteases. However the diatom Chaetoceros didymus is fully resistant against the bacterial enzymes. We show that the growth curve of this diatom is essentially unaffected by addition of bacterial filtrates that are active against other diatoms. By monitoring proteases from the medium using zymography and fluorescence based activity assays we demonstrate that C. didymus responds to the presence of the lytic bacteria with the induced production of algal proteases. These proteases exhibit a substantially increased activity compared to the bacterial counterparts. The induction is also triggered by signals in the supernatant of a K. algicida culture. Size fractionation shows that only the >30 kD fraction of the bacterial exudates acts as an inducing cue. Implications for a potential induced defense of the diatom C. didymus are discussed.

Interactions of the algicidal bacterium Kordia algicida with diatoms: regulated protease excretion for specific algal lysis.

Interactions of planktonic bacteria with primary producers such as diatoms have great impact on plankton population dynamics. Several studies described the detrimental effect of certain bacteria on diatoms but the biochemical nature and the regulation mechanism involved in the production of the active compounds remained often elusive. Here, we investigated the interactions of the algicidal bacterium Kordia algicida with the marine diatoms Skeletonema costatum, Thalassiosira weissflogii, Phaeodactylum tricornutum, and Chaetoceros didymus. Algicidal activity was only observed towards the first three of the tested diatom species while C. didymus proved to be not susceptible. The cell free filtrate and the >30 kDa fraction of stationary K. algicida cultures is fully active, suggesting a secreted algicidal principle. The active supernatant from bacterial cultures exhibited high protease activity and inhibition experiments proved that these enzymes are involved in the observed algicidal action of the bacteria. Protease mediated interactions are not controlled by the presence of the alga but dependent on the cell density of the K. algicida culture. We show that protease release is triggered by cell free bacterial filtrates suggesting a quorum sensing dependent excretion mechanism of the algicidal protein. The K. algicida / algae interactions in the plankton are thus host specific and under the control of previously unidentified factors.

Detection of extracellular protease activity in different species and genera of ectomycorrhizal fungi

In northern forest ecosystems, most soil nitrogen (N) is in organic form and forest trees are largely dependent on ectomycorrhizal (ECM) fungi and their degradative abilities for N uptake. The ability of ECM fungi to acquire N from organic substrates should, therefore, be a widespread trait given its ecological importance. However, little is known about the degradative abilities of most ECM fungi as they remain untested due to problems of isolation or extremely slow growth in pure culture. In this paper, we present data on extracellular protease activity of 32 species of ECM fungi, most of which have not previously been cultured. Milk powder plates and zymograms were compared for detecting protease activity in these intractable species. In total, 29/32 of the species produced extracellular protease activity, but detection was method dependent. Growth on milk powder plates detected protease activity in 28 of 32 species, while zymograms only detected proteases in Amanita muscaria, Russula chloroides, Lactarius deterrimus and Lactarius quieticolor. The study supports the hypothesis that protease excretion is a widespread physiological trait in ECM fungi and that this ability is of considerable significance for nitrogen uptake in forest ecosystems.

Effect of sucrose, inorganic salts, inositol, and thiamine on protease excretion during pineapple culture in temporary immersion bioreactors

Although pineapple plants have been found to produce proteases ex vitro, most of the biotechnological investigations of this crop have been focused on propagation. The procedure involving the use of temporary immersion bioreactors is one of the most outstanding because of its high multiplication rate. We previously recorded specific protease activity in the culture medium during the pre-elongation step of this protocol. Therefore, we decided to modify the culture medium composition of this phase looking for an increase in protease excretion. Four independent experiments were performed to evaluate the effects of different levels of sucrose (0–350.4 mM), inorganic salts [0–200% Murashige and Skoog (MS) salt strength], inositol (0–2.20 mM), and thiamine (0–1.2μM). The following indicators were recorded: shoot fresh mass per bioreactor; and protein concentration, proteolytic activity, and specific protease activity in culture media. Specific protease activity, the most important indicator recorded, was highest with 262.8 mM sucrose, 100% MS salt strength, 0.3 μM thiamine and no inositol. Results shown here demonstrate that conditions adequate for propagation purposes (87.6 mM sucrose, 100% MS salt strength, 0.55 mM inositol, 0.3 μM thiamine) are not always adequate for protease excretion.

Protease excretion during pineapple micropropagation in temporary immersion bioreactors

Biotechnology has become an important tool to produce plant secondary metabolites and proteases are among them. Although pineapple plants have been found to produce proteases, most of the biotechnological investigations on this crop have been focused on propagation. The procedure involving the use of temporary immersion bioreactors is one of the most outstanding because of its high multiplication rate. We previously recorded specific protease activity in the culture medium during the pre-elongation step of this protocol. Therefore we decided to modify this phase, looking for an increase of protease excretion. Three independent experiments were performed to evaluate the effects of culture duration, and levels of gibberellic acid (GA) and 6-benzyladenine (BA). The following indicators were recorded: shoot fresh mass per bioreactor; and protein concentration, proteolytic activity, and specific protease activity in culture media. As happens in investigations focused on protease production, the specific protease activity was the most important indicator recorded here. It maximized at 21 d of culture. Moreover, GA (4.2 μM) increased specific activity in the culture medium while BA produced a negative effect. Results shown here demonstrate that conditions adquate for propagation purposes (15-d pre-elongation phase; 2.8 μM GA; 2.2 μM BA) are not necessarily adequate for protease excretion.

Biosynthesis and properties of an extracellular metalloprotease from the Antarctic marine bacterium Sphingomonas paucimobilis

An extracellular protease from the marine bacterium Sphingomonas paucimobilis, strain 116, isolated from the stomach of Antarctic krill, Euphausia superba Dana, was purified and characterized. The excretion of protease was maximal at temperatures from 5 to 10°C, i.e. below the temperature optimum for the strain growth (15°C). The highly purified enzyme was a metalloprotease [sensivity to ethylenediaminetetraacetic acid (EDTA)] and showed maximal activity against proteins at 20–30°C and pH 6.5–7.0, and towards N-benzoyl-tyrosine ethyl ester (BzTyrOEt) at pH 8.0. At 0°C the enzyme retained as much as 47% of maximal activity in hydrolysis of urea denatured haemoglobin (Hb) (at pH 7.0), and at −5 and −10°C, 37 and 30%, respectively. The metalloprotease was stable up to 30°C for 15 min and up to 20°C for 60 min. These results indicate that the proteinase from S. paucimobilis 116 is a cold-adapted enzyme.

Extracellular protease production by psychrotrophic bacteria from glaciers

The effects of temperature, time and medium composition on protease formation and on the growth of 25 psychrotrophic bacteria from glaciers were investigated. In addition to their ability to grow at low temperatures, psychrotrophic strains demonstrated a cold dependent enzyme production. More than growth, the excretion of proteases into the medium was shown to be dependent on the cultivation temperature. Protease production by all 25 strains was influenced by medium composition, which demonstrates the temperature dependency of this process.

A comparison of extracellular proteases from three psychrotrophic strains of Pseudomonas fluorescens.

Extracellular proteases from three psychrotrophic strains of Pseudomonas fluorescens were purified and characterized. The cultivation temperature decisively influenced the excretion of protease into the medium. Highest enzyme production occurred at 10°C (one strain) or 20°C (two strains). The purified proteases showed a molecular weight between 47kDa and 51kDa, the pI values ranged from 7.8 to 7.4. All three proteases were characterized by several closely focused bands. Sensitivity to metalchelating agents indicates that P. fluorescens proteases are metalloproteases (EC 3.4.24). The pH optimum for azocaseinolytic activity was at pH 6-7, the temperature optimum was at 40-45°C. The apparent energies of activation were 36.9-38.0kJ mol-1. The proteases were thermolabile. By adding calcium ion an increasing thermostability was observed. SDS, urea and several metal ions inhibited proteolytic activities to different extents. Casein was the preferred substrate for the proteases. With casein concentrations up to 0.4-0.75% a Michaelis-Menten-type kinetics was observed, at higher casein concentrations a substrate inhibiton occurred. None of the proteases showed aminopeptidase activity.

Characterization of a metalloprotease from psychrophilic Xanthomonas maltophilia

An extracellular protease from psychrophilic Xanthomonas maltophilia isolated from alpine environment was purified and characterized. In spite of a comparable growth at 10°C and 20°C, protease excretion occured only at 10°C. The enzyme was a 21-kDa protein with an isoelectric point higher than 9.5. The optimum pH and temperature for azocaseinolytic activity were 8.0 and 50°C respectively. The enzyme was stable up to 40°C but became inactive after 10 min at 60°C. The energy of activation was comparable to that of enzymes from mesophilic sources. Sensitivity to EDTA indicates that X. maltophilia protease is a metalloprotease.

Characterization of a metalloprotease from psychrophilicXanthomonas maltophilia

An extracellular protease from psychrophilic Xanthomonas maltophilia isolated from alpine environment was purified and characterized. In spite of a comparable growth at 10°C and 20°C, protease excretion occured only at 10°C. The enzyme was a 21-kDa protein with an isoelectric point higher than 9.5. The optimum pH and temperature for azocaseinolytic activity were 8.0 and 50°C respectively. The enzyme was stable up to 40°C but became inactive after 10 min at 60°C. The energy of activation was comparable to that of enzymes from mesophilic sources. Sensitivity to EDTA indicates that X. maltophilia protease is a metalloprotease.

Urinary proteinase activity in patients with acute renal failure after trauma and kidney transplantation.

A pathophysiological stress that produced a “hypercatabolic” metabolic state often will cause an increased basal energy expenditure in addition to eccessive loss of body protein. This condition is further characterized by severe muscle wasting and increased urinary nitrogen excretion. Both protein synthesis and breakdown are stimulated in severe skeletal trauma (Birkhahn et al., 1981), sepsis (Long et al., 1977) and after burn (Kien et al. 1978). Under these conditions enhanced proteolytic activity in plasma ultrafiltrates and urine fractions of patients with severe trauma and acute renal failure has been reported (Hörl and Heidland, 1980; Hörl et al., 1981; 1982a; 1983; 1986). Until now, the effect of postischemic acute renal failure on urinary protease excretion has not been investigated. Therefore, the present study was undertaken to compare urinary protease activity in patients with acute renal failure after cadaveric kidney transplantation and following multiple traumatic injuries. Furthermore, the proteolytic enzymes involved were partly characterized.KeywordsAcute Renal FailureKidney TransplantationCyanogen BromideSubunit StructureNormal Kidney FunctionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Urinalysis for detection of chemically induced renal damage (1)--Changes in urinary excretions of enzymes and various components caused by mercuric chloride and gentamicin.

In order to establish sensitive methods of detecting minor renal damage, changes of enzymes, tubular cell counts, and creatinine in the urine were investigated in rats that had been given nephrotoxic chemicals. Daily administration of mercuric chloride (HgCl2) dose-dependently increased urinary excretions of lactate dehydrogenase (LDH), aspartate aminotransferase (GOT), alkaline phosphatase (ALP), leucine aminopeptidase (LAP), lysozyme (LZM), N-acetyl-beta-D-glucosaminidase (NAG), and acid protease together with increased counts of tubular cells in the urine. The increase in tubular cell counts and the change in urinary LDH isoenzyme profile preceded the changes in the other enzymes. Daily administration of gentamicin (GM) increased urinary excretions of LDH, GOT, LZM, NAG, acid protease and tubular cell counts in a dose-dependent manner, but did not increase gamma-glutamyl transpeptidase (gamma-GTP) and ALP excretions. The urinary isoenzyme profiles of LDH in rats treated with GM were different from those with HgCl2. The increase in acid protease excretion outlasted those in LDH and GOT in the high dose group. It was concluded that the severity of renal damage can be readily detected by periodic determinations of the following urinary parameters: tubular cell counts, LDH isoenzyme, acid protease, LZM and NAG, in addition to either LDH or GOT and one of the enzymes ALP, LAP or gamma-GTP. Furthermore, the site of renal damage can be presumed from these results.

Specific excretion of Serratia marcescens protease through the outer membrane of Escherichia coli.

A DNA fragment of Serratia marcescens directing an extracellular serine protease (Mr, 41,000) was cloned in Escherichia coli. The cloned fragment caused specific excretion of the protease into the extracellular medium through the outer membrane of E. coli host cells in parallel with their growth. No excretion of the periplasmic enzymes of host cells occurred. The cloned fragment contained a single open reading frame of 3,135 base pairs coding a protein of 1,045 amino acids (Mr 112,000). Comparison of the 5' nucleotide sequence with the N-terminal amino acid sequence of the protease indicated the presence of a typical signal sequence. The C-terminal amino acid of the enzyme was found at position 408, as deduced from the nucleotide sequence. Artificial frameshift mutations introduced into the coding sequence for the assumed distal polypeptide after the C terminus of the protease caused complete loss of the enzyme production. It was concluded that the Serratia serine protease is produced as a 112-kilodalton proenzyme and that its N-terminal signal peptide and a large C-terminal part are processed to cause excretion of the mature protease through the outer membrane of E. coli cells.

Urine protease and antiprotease activity in experimental aminonucleoside nephrotoxicity.

Induction of nephrosis in rats with aminonucleoside of puromycin (ANP) was followed by an increase in urinary protease activity, measured by the cleavage of 14C-globin, as well as in antiprotease activity measured by trypsin inhibition. The excretion of protease and protease inhibitor coincided with but did precede the onset of proteinuria when the ANP was injected subcutaneously for 5 days and lagged after proteinuria when the ANP was given as a single intravenous dose. Serum protease activity did not change throughout ANP treatment or later, whereas serum antiprotease capacity declined coincidently with proteinuria, most probably due to the loss in urine. Kidney proteolytic activity was markedly reduced in ANP nephrosis. Treatment of rats with proteolysis inhibitors, trasylol, episilon-aminocaproic acid, soybean trypsin inhibitor, or hexapron, together with ANP failed to prevent, delay or reduce the proteinuria. We believe that the urinary protease in ANP nephrosis does not originate from the circulation but from the release of kidney protease as a consequence of the glomerular lesion, and does not appear to be involved in its causation.