strain K30 latex clearing protein

Polyethylene is the most commonly used plastic product, and its biodegradation is a worldwide problem. Latex clearing protein derived from Streptomyces sp. strain K30 (LcpK30) has been reported to be able to break the carbon-carbon double bond inside oxidized polyethylene and is an effective biodegradation enzyme for polyethylene. However, the binding of the substrate to the enzyme was difficult due to the hydrophobic nature of polyethylene. Therefore, to further improve the efficiency of LcpK30, the effect of different anchor peptides on the binding capacity of LcpK30 to the substrate was screened in this study. The results of fluorescence confocal microscopy showed that the anchoring peptide LCI had the most significant improvement in effect and was finally selected for further application in a UV-irradiated PE degradation system. The degradation results showed that LCI was able to improve the degradation efficiency of LcpK30 by approximately 1.15 times in the presence of equimolar amounts of protein compared with wild-type. This study further improves the application of LcpK30 in the field of polyethylene degradation by modification.

Engineered Anchor Peptide LCI with a Cobalt Cofactor Enhances Oxidation Efficiency of Polystyrene Microparticles

A typical component of polymer waste is polystyrene (PS) used in numerous applications, but degraded only slowly in the environment due to its hydrophobic properties. To increase the reactivity of polystyrene, polar groups need to be introduced. Here, biohybrid catalysts based on the engineered anchor peptide LCI_F16C are presented, which are capable of attaching to polystyrene microparticles and hydroxylating benzylic C-H bonds in polystyrene microparticles using commercially available oxone as oxidant. LCI peptides achieve a dense surface coverage of PS through monolayer formation within minutes in aqueous solutions at ambient temperature. The catalytically active cobalt cofactor Co-L1 or Co-L2 with a modified NNNN macrocyclic TACD ligand (TACD=1,4,7,10-tetraazacyclododecane) is covalently bound to the anchor peptide LCI through a maleimide linker. Compared to the free cofactors, a 12- to 15-fold improvement in catalytic activity using biohybrid catalysts based on LCI_F16C was observed.

Bifunctional peptides as alternatives to copper-based formulations to control citrus canker

Citrus canker is an infectious bacterial disease and one of the major threats to the orange juice industry, a multibillion-dollar market that generates hundreds of thousands of jobs worldwide. This disease is caused by the Gram-negative bacterium Xanthomonas citri subsp. citri. In Brazil, the largest producer and exporter of concentrate orange juice, the control of citrus canker is exerted by integrated management practices, in which cupric solutions are intensively used in the orchards to refrain bacterial spreading. Copper ions accumulate and are as heavy metals toxic to the environment. Therefore, the aim of the present work was to evaluate bifunctional fusion proteins (BiFuProts) as novel and bio-/peptide-based alternatives to copper formulations to control citrus canker. BiFuProts are composed of an anchor peptide able to bind to citrus leaves, and an antimicrobial "killer" peptide to protect against bacterial infections of plants. The selected BiFuProt (Mel-CgDEF) was bactericidal against X. citri at 125 μg mL-1, targeting the bacterial cytoplasmic membrane within the first minutes of contact. The results in the greenhouse assays proved that Mel-CgDEF at 250 μg mL-1 provided protection against X. citri infection on the leaves, significantly reducing the number of lesions by area when compared with the controls. Overall, the present work showed that the BiFuProt Mel-CgDEF is a biobased and biodegradable possible alternative for substitute cupric formulations. KEY POINTS: • The bifunctional fusion protein Mel-CgDEF was effective against Xanthomonas citri. • Mel-CgDEF action mechanism was the disruption of the cytoplasmic membrane. • Mel-CgDEF protected citrus leaves against citrus canker disease.

Enzyme mimetic microgel coating for endogenous nitric oxide mediated inhibition of platelet activation

Nitric oxide (NO) continuously generated by healthy endothelium prevents platelet activation and maintains vascular homeostasis. However, when artificial surfaces, like of extracorporeal membrane oxygenator comes in contact with blood, protein adsorption and thereby platelet activation takes place, which eventually leads to thrombus formation. To overcome this, we present an antifouling microgel coating mimicking the function of enzyme glutathione peroxidase to endogenously generate NO in the blood plasma from endogenous NO-donors and maintain a physiological NO flux. Microgels are synthesized by copolymerization of highly hydrophilic N-(2-hydroxypropyl)methacrylamide (HPMA) and glycidyl methacrylate (GMA) with diselenide crosslinks. For immobilization of the microgels on hydrophobic poly(4-methylpentene) (TPX) membranes bioengineered amphiphilic anchor peptides with free thiols are used. The anchor peptide attaches to the TPX membranes by hydrophobic interactions while the free thiols are presented for crosslinking with the microgels. The hydrophilic nature of the microgel coating prevents protein adsorption while the reversible diselenide bridges make the microgels responsive to the reducing environment and lead to the formation of reactive selenols/selenolates. The generated selenols/selenolates provide an efficient and sustained NO-release from endogenous S-nitrosothiols (RSNOs) mimicking the enzymatic function of glutathione peroxidase. On exposure to the whole blood, the microgel coating inhibited platelet activation and prolonged the blood clotting time.

Anchor peptides promote degradation of mixed plastics for recycling

Resource stewardship and sustainable use of natural resources is mandatory for a circular plastic economy. The discovery of microbes and enzymes that can selectively degrade mixed-plastic waste enables to recycle plastics. Knowledge on how to achieve efficient and selective enzymatic plastic degradation is a key prerequisite for biocatalytic recycling of plastics. Wild-type natural polymer degrading enzymes such as cellulases pose often selective non-catalytic binding domains that facilitate a targeting and efficient degradation of polymeric substrates. Recently identified polyester hydrolases with synthetic polymer degrading activities, however, lack in general such selective domains. Inspired by nature, we herein report a protocol for the identification and engineering of anchor peptides which serve as non-catalytic binding domains specifically toward synthetic plastics. The identified anchor peptides hold the promise to be fused to known plastic degrading enzymes and thereby enhance the efficiency of biocatalytic plastic recycling processes.