Purification, characterization and the use of recombinant prolyl oligopeptidase from Myxococcus xanthus for gluten hydrolysis

Multipotential Alkaline Protease From a Novel Pyxidicoccus sp. 252: Ecofriendly Replacement to Various Chemical Processes

A newly isolated alkaline protease-producing myxobacterium was isolated from soil. The strain was identified as Pyxidicoccus sp. S252 on the basis of 16S rRNA sequence analysis. The extracellular alkaline proteases produced by isolate S252 (PyCP) was optimally active in the pH range of 11.0–12.0 and temperature range of 40–50°C The zymogram of PyCP showed six caseinolytic protease bands. The proteases were stable in the pH range of 8.0–10.0 and temperature range of 40–50°C. The activity of PyCP was enhanced in the presence of Na⁺, Mg²⁺, Cu²⁺, Tween-20, and hydrogen peroxide (H₂O₂) (hydrogen peroxide), whereas in Triton X-100, glycerol, ethylenediaminetetraacetic acid (EDTA), and Co²⁺, it was stable. PyCP showed a potential in various applications. The addition of PyCP in the commercial detergent enhanced the wash performance of the detergent by efficiently removing the stains of tomato ketchup and coffee. PyCP efficiently hydrolyzed the gelatin layer on X-ray film to release the embedded silver. PyCP also showed potent dehairing of goat skin and also efficiently deproteinized sea shell waste indicating its application in chitin extraction. Thus, the results of the present study indicate that Pyxidicoccus sp. S252 proteases have the potential to be used as an ecofriendly replacement of chemicals in several industrial processes.

Gluten-degrading bacteria: availability and applications

Gluten is a mixture of storage proteins in wheat and occurs in smaller amounts in other cereal grains. It provides favorable structure to bakery products but unfortunately causes disease conditions with increasing prevalence. In the human gastrointestinal tract, gluten is cleaved into proline and gluten rich peptides that are not degraded further. These peptides trigger immune responses that might lead to celiac disease, wheat allergy, and non-celiac gluten sensitivity. The main treatment option is a gluten-free diet. Alternatively, using enzymes or microorganisms with gluten-degrading properties might alleviate the disease. These components can be used during food production or could be introduced into the digestive tract as food supplements. In addition, natural food from the environment is known to enrich the microbial communities in gut and natural environmental microbial communities have high potential to degrade gluten. It remains to be investigated if food and environment-induced changes in the gut microbiome could contribute to the triggering of gluten-related diseases. KEY POINTS: • Wheat proteins, gluten, are incompletely digested in human digestive tract leading to gluten intolerance. • The only efficient treatment of gluten intolerance is life-long gluten-free diet. • Environmental bacteria acquired together with food could be source of gluten-degrading bacteria detoxifying undigested gluten peptides.

Biosynthesis of Cittilins, Unusual Ribosomally Synthesized and Post-translationally Modified Peptides from Myxococcus xanthus

Cittilins are secondary metabolites from myxobacteria comprised of three l-tyrosines and one l-isoleucine forming a bicyclic tetrapeptide scaffold with biaryl and aryl-oxygen-aryl ether bonds. Here we reveal that cittilins belong to the ribosomally synthesized and post-translationally modified peptide (RiPP) family of natural products, for which only the crocagins have been reported from myxobacteria. A 27 amino acid precursor peptide harbors a C-terminal four amino acid core peptide, which is enzymatically modified and finally exported to yield cittilins. The small biosynthetic gene cluster responsible for cittilin biosynthesis also encodes a cytochrome P450 enzyme and a methyltransferase, whereas a gene encoding a prolyl endopeptidase for the cleavage of the precursor peptide is located outside of the cittilin biosynthetic gene cluster. We confirm the roles of the biosynthetic genes responsible for the formation of cittilins using targeted gene inactivation and heterologous expression in Streptomyces ssp. We also report first steps toward the biochemical characterization of the proposed biosynthetic pathway in vitro. An investigation of the cellular uptake properties of cittilin A connected it to a potential biological function as an inhibitor of the prokaryotic carbon storage regulator A (CsrA).

Prolyl Oligopeptidase From Leishmania infantum: Biochemical Characterization and Involvement in Macrophage Infection

Leishmania infantum is a flagellated protozoan and one of the main causative agents of visceral leishmaniasis. This disease usually affects the human reticuloendothelial system, can cause death and available therapies may lead to serious side effects. Since it is a neglected tropical disease, the incentives for the development of new drugs are insufficient. It is important to know Leishmania virulence factors that contribute most to the disease in order to develop drugs. In the present work, we have produced L. infantum prolyl oligopeptidase (rPOPLi) in Escherichia coli, and investigated its biochemical properties as well as the effect of POP inhibitors on its enzymatic activity and on the inhibition of the macrophage infection by L. infantum. The optimal activity occurred at pH 7.5 and 37°C in the presence of DTT, the latter increased rPOPLi catalytic efficiency 5-fold on the substrate N-Suc-Gly-Pro-Leu-Gly-Pro-AMC. The enzyme was inhibited by TPCK, TLCK and by two POP specific inhibitors, Z-Pro-prolinal (ZPP, IC₅₀ 4.2 nM) and S17092 (IC₅₀ 3.5 nM). Besides being a cytoplasmic enzyme, POPLi is also found in punctuate structures within the parasite cytoplasm or associated with the parasite plasma membrane in amastigotes and promastigotes, respectively. Interestingly, S17092 and ZPP prevented parasite invasion in murine macrophages, supporting the involvement of POPLi in the invasive process of L. infantum. These data suggest POPLi as a virulence factor that offers potential as a target for designing new antileishmanial drugs.

Extraction and characterization of novel multifunctional peptides from Trachinus Draco (greater weever) myofibrillar proteins with ACE/DPP4 inhibitory, antioxidant, and metal chelating activities

Marine organisms represent a great source of natural bioactive molecules, from which bioactive peptides are of great importance in biomedicine application in many diseases such as diabetes and its related complications. In this study, greater weever (Trachinus Draco) myofibrillar proteins were sequentially hydrolyzed and the different RP-HPLC purified fractions were tested for potential inhibitory activities of ACE and DPP4, in addition to metal chelation and antioxidant activities. Four fractions were found to have high levels of activity (with two peptides being multifunctional) and were subsequently sequenced using the de novo sequencing method. The results indicate that the peptides are novel and highly effective for each related activity compared to reference molecules. The current findings suggest these multifunctional peptides as promising therapeutics against oxidative stress, hypertension, and diabetes. PRACTICAL APPLICATIONS: We have described the finding of two multifunctional bioactive peptides from Trachinus Draco (greater weever) myofibrillar proteins having two or more activities. They have ACE inhibitory, DPP4 inhibitory, antioxidant, and metal chelation activities. These new peptides could be used for future biomedicine applications as a stand-alone treatment, in combination with other molecules, or as a supplement. Furthermore, after identification of their sequence in our work, it would have a great potential to be artificially synthesized. The field of food supplements could be explored further.

Role of Dietary Gluten in Development of Celiac Disease and Type I Diabetes: Management Beyond Gluten-Free Diet

Gluten triggers Celiac Disease (CD) and type I diabetes in genetically predisposed population of human leukocyte antigen DQ2/DQ8+ and associates with disorders such as schizophrenia and autism. Application of a strict gluten-free diet is the only well-established treatment for patients with CD, whereas the treatment for patients with celiac type I diabetes may be depend on the timing and frequency of the diet. The application of a gluten-free diet in patients with CD may contribute to the development of metabolic syndrome and nonalcoholic fatty liver disease and may also lead to a high glycemic index, low fiber diet and micronutrient deficiencies. The alteration of copper bioavailability (deficient, excess or aberrant coordination) may contribute to the onset and progress of related pathologies. Therefore, nutrient intake of patients on a gluten-free diet should be the focus of future researches. Other gluten-based therapies have been rising with interest such as enzymatic pretreatment of gluten, oral enzyme supplements to digest dietary gluten, gluten removal by breeding wheat varieties with reduced or deleted gluten toxicity, the development of polymeric binders to suppress gluten induced pathology.

S9A Serine Protease Engender Antigenic Gluten Catabolic Competence to the Human Gut Microbe

The human gut microbiome has a significant role in host physiology; however its role in gluten catabolism is debatable. Present study explores the role of human gut microbes in gluten catabolism and a native human gut microbe Cellulomonas sp. HM71 was identified. SSU rDNA analysis has described human gut microbiome structure and also confirmed the permanent residentship of Cellulomonas sp. HM71. Catabolic potential of Cellulomonas sp. HM71 to cleave antigenic gluten peptides indicates presence of candidate gene encoding biocatalytic machinery. Genome analysis has identified the presence of gene encoding S9A serine protease family-prolyl endopeptidase, with Ser591, Asp664 and His685 signature residues. Cellulomonas sp. HM71 prolyl endopeptidase activity was found optimal at pH 7.0 and 37 °C with a K_M of 35.53 μmol and specifically cleaves at proline residue. Current study describes the gluten catabolism potential of Cellulomonas sp. HM71 depicting possible role of human gut microbes in gluten catabolism to confer resistance mechanisms for the onset of celiac diseases in populations with gluten diet.