Purification and characterisation of a protease inhibitor from Streptomyces chromofuscus 34-1 with an antiviral activity

Unraveling a natural protease inhibitor from marine Streptomyces griseoincarnatus HK12 active against Chikungunya virus

Proteases play an indispensable role in the life cycles of several life-threatening organisms such as the ones causing malaria, cancer and AIDS. A targeted blockade of these enzymes could be an efficient approach for drug modeling against these causative agents. Our study was directed towards the extraction and characterization of a protease inhibitor having activity against Chikungunya virus (CHIKV). A protein-based protease inhibitor (PI) in Streptomyces griseoincarnatus HK12 with anti-viral activity against CHIKV was revealed when screened against two major proteases, papain and trypsin. The PI was efficiently extracted at 60 % ammonium sulfate saturation and purified by ion-exchange chromatography (CM-Sepharose) at 300 mM NaCl elution followed by SDS-PAGE (10 %). The protein was characterized by denaturing SDS-PAGE, reverse zymography, and MALDI-TOF peptide mass fingerprinting. The protein-based PI was studied to have a high molecular weight of 66-70 kDA. The PI was tested to supress the supress cytopathic effects (CPE) exerted by the clinically isolated virus in BHK21 cells. This was used as a measure to determine the antiviral activity. The PI exerted significant effects with an effective concentration calculated as EC₅₀ 11.21 μg/mL. The protein was found to be reported as the first of its kind which also stands out to be the first a natural protease inhibitor against the treatment of the chikungunya virus.

Could Probiotics and Postbiotics Function as "Silver Bullet" in the Post-COVID-19 Era?

We are currently experiencing the realities of the most severe pandemic within living memory, with major impacts on the health and economic well-being of our planet. The scientific community has demonstrated an unprecedented mobilization capability, with the rapid development of vaccines and drugs targeting the protection of human life and palliative measures for infected individuals. However, are we adequately prepared for ongoing defense against COVID-19 and its variants in the post-pandemic world? Moreover, are we equipped to provide a satisfactory quality of life for individuals who are recovering from COVID-19 disease? What are the possibilities for the acceleration of the recovery process? Here, we give special consideration to the potential and already-demonstrated role of probiotics and traditional medical approaches to the management of current and potential future encounters with our major virus adversaries.

Secondary metabolites and biodiversity of actinomycetes

BACKGROUND

The ability to produce microbial bioactive compounds makes actinobacteria one of the most explored microbes among prokaryotes. The secondary metabolites of actinobacteria are known for their role in various physiological, cellular, and biological processes.

MAIN BODY

Actinomycetes are widely distributed in natural ecosystem habitats such as soil, rhizosphere soil, actinmycorrhizal plants, hypersaline soil, limestone, freshwater, marine, sponges, volcanic cave-hot spot, desert, air, insects gut, earthworm castings, goat feces, and endophytic actinomycetes. The most important features of microbial bioactive compounds are that they have specific microbial producers: their diverse bioactivities and their unique chemical structures. Actinomycetes represent a source of biologically active secondary metabolites like antibiotics, biopesticide agents, plant growth hormones, antitumor compounds, antiviral agents, pharmacological compounds, pigments, enzymes, enzyme inhibitors, anti-inflammatory compounds, single-cell protein feed, and biosurfactant.

SHORT CONCLUSIONS

Further highlight that compounds derived from actinobacteria can be applied in a wide range of industrial applications in biomedicines and the ecological habitat is under-explored and yet to be investigated for unknown, rare actinomycetes diversity.

Modeling of growth kinetics for an isolated marine bacterium, Oceanimonas sp. BPMS22 during the production of a trypsin inhibitor

Protease inhibitors significantly control physiologically relevant protease activities. Protease inhibitors from marine microbial sources are unique due to their rough living environmental conditions. In the present study, a protein protease inhibitor (PI) was produced from marine Oceanimonas sp. BPMS22. Seven different media were screened for the growth of the bacterium and production of PI. Different carbon and nitrogen sources were screened and optimized for the specific protease inhibitor activity. Three different growth models were checked for the best fit of the bacterial growth. A modified Gompertz model was selected as the best model for the growth of Oceanimonas sp. BPMS22 with the maximum specific growth rate of 0.165 hr^-1 and doubling time of 4.2 hr. The production of PI takes place during the non-growing phase of the bacterial growth. A kinetic model for the production of PI during non-growing phase was used for studying various process parameters. From the model, the maximum trypsin inhibitor formation rate of 0.3802 IU per mg of biomass per hour was observed at 49.91 hr.

Microbial serine protease inhibitors and their therapeutic applications

Serine protease inhibitors, inhibit serine proteases either partially or completely after forming complexes with their respective proteases. Protease actions are significant for many physiological pathways found in living forms and any anomalies may lead to numerous physiological complications. Each cell or organism has its own mechanism for controlling these protease actions. It is often regulated by the action of inhibitors or activators. Among the proteases, serine proteases are the most common that are involved in many life and death processes. Selective inhibitors of physiologically relevant proteases can be used as a lead compound for the drug development. Therefore, it is imperative to identify small peptides and proteins that selectively inhibit serine proteases from various sources. Microbes can be considered as a major source of diverse serine protease inhibitors since they have the prominent and diverse domain in nature. Most of the microbial serine protease inhibitors are intracellular and few are extracellular. Microbes produce protease inhibitors for protection against its own proteases or against other environmental factors. The status and future prospects of microbial serine protease inhibitors and their therapeutic benefits in treating cancer, blood coagulation disorders and viral infections, are reviewed here.

Isolation, purification and characterization of a pH tolerant and temperature stable proteinaceous protease inhibitor from marine Pseudomonas mendocina

OBJECTIVES

An extracellular protease inhibitor (BTPI-301) of trypsin was purified and characterized from an isolate of Pseudomonas mendocina.

RESULTS

BTPI-301was purified to homogeneity by (NH₄)₂SO₄, precipitation, DEAE Sepharose and CNBr-activated Sepharose chromatography. Homogeneity was proved by native PAGE and SDS-PAGE. The intact molecular mass was 11567 Da by MALDI-TOF analysis. BTPI-301was a competitive inhibitor with a Ki of 3.5 × 10^-10 M. It was stable and active at pH 4-12 and also at 4-90 °C for 1 h. Peptide mass fingerprinting by MALDI revealed that the BTPI-301 is a new inhibitor not reported so far with protease inhibitory activity. The pI of the inhibitor was 3.8. The stoichiometry of trypsin-BTPI-301 interaction is 1:1. The inhibitor was specific towards trypsin.

CONCLUSION

A pH tolerant and thermostable protease inhibitor BTPI-301 active against trypsin was purified and characterized from P. mendocina that could be developed and used as biopreservative as well as biocontrol agent.

Effect of a plant polyphenol-rich extract on the lung protease activities of influenza-virus-infected mice

Influenza infection was induced in white mice by intranasal inoculation of the virus A/Aichi/2/68 (H3N2). The lung protease and the protease-inhibitory activities were followed for 9 days after infection. The intranasal application of a polyphenol-rich extract (PC) isolated from Geranium sanguineum L. induced a continuous rise in the anti-protease activity but did not cause substantial changes in the lung protease activity of healthy mice. Influenza virus infection triggered a slight reduction in protease activity in the lungs at 5 and 48 h post infection (p.i.) and a marked increase at 24 h and 6 day p.i.. Protease inhibition in the lungs was reduced at 24 and 48 h p.i. and an increase was observed at 5 h and 6 and 9 days p.i.. PC treatment brought both activities to normal levels. The restoration of the examined parameters was consistent with a prolongation of mean survival time and reduction of mortality rate, infectious virus titre and lung consolidation. PC reinstated superoxide production by alveolar macrophages and increased their number in virus-infected mice. The favourable effect on the protease and the protease-inhibitory activities in the lungs of influenza-virus-infected mice apparently contributes to the overall protective effect of PC in the murine experimental influenza A/Aichi infection. The antiviral effect of the individual constituents was evaluated.