Expression, purification and thermostability of MBP-chondroitinase ABC I from Proteus vulgaris

Identification and characterization of a chondroitinase ABC with a novel carbohydrate-binding module

Chondroitinases play important roles in structural and functional studies of chondroitin sulfates. Carbohydrate-binding module (CBM) is generally considered as an accessory module in carbohydrate-active enzymes, which promotes the association of the appended enzyme with the substrate and potentiates the catalytic activity. However, the role of natural CBM in chondroitinases has not been investigated. Herein, a novel chondroitinase ChABC29So containing an unknown domain with a predicted β-sandwich fold was discovered from Segatella oris. Recombinant ChABC29So showed enzyme activity towards chondroitin sulfates and hyaluronic acid and acted in a random endo-acting manner. The unknown domain exhibited a chondroitin sulfate-binding capacity and was identified as a CBM. Biochemical characterization of ChABC29So and the CBM-truncated enzyme revealed that the CBM enhances the catalytic activity, thermostability, and disaccharide proportion in the final enzymatic products of ChABC29So. These findings demonstrate the role of the natural CBM in a chondroitinase and will guide future modification of chondroitinases.

Efficient Expression and Characterization of an Endo-Type Lyase HCLase_M28 and Its Gradual Scale-Up Fermentation for the Preparation of Chondroitin Sulfate Oligosaccharides

Glycosaminoglycan (GAG) lyases have been critical in structural and functional studies of GAGs. HCLase_M28, a lyase identified from the genome of Microbacterium sp. M28 was heterologously expressed, enzymatically characterized, and prepared in large-scale fermentation for the production of chondroitin sulfate (CS) oligosaccharides. Results showed that the expression of HCLase_M28 in Escherichia coli BL21 (DE3)-pET24a-HCLase_M28opt1 and Bacillus subtilis W800-pSTOP1622-HCLase_M28opt2 were 108-fold and 25-fold that of wide strain. The optimal lytic reaction of HCLase_M28 happened in 20 mM Tris-HCl (pH 7.2) at 50 °C with a specific activity of 190.9 U/mg toward CS-A. The degrading activity was slightly simulated in presence of 1 mM Ca2+ and Mn2+ while severely inhibited by Hg+, Cu2+, Fe3+, and SDS. TLC and ESI-MS analysis proved HCLase_M28 was an endolytic lyase and degraded CS and hyaluronic acid into unsaturated disaccharides. Through a gradual scale-up of fermentation in 5 L, 100 L, and 1000 L, a highly efficient intracellular expression of HCLase_M28 with an activity of 3.88 × 105 U/L achieved within a 34 h of cultivation. Through ultrafiltration, CS oligosaccharides with DP of 2 to 8 as the main components could be controllably prepared. The successful large-scale fermentation made HCLase_M28 a promising enzyme for industrial production of CS oligosaccharides.

YsHyl8A, an Alkalophilic Cold-Adapted Glycosaminoglycan Lyase Cloned from Pathogenic Yersinia sp. 298

A high enzyme-yield strain Yersinia sp. 298 was screened from marine bacteria harvested from the coastal water. The screening conditions were extensive, utilizing hyaluronic acid (HA)/chondroitin sulfate (CS) as the carbon source. A coding gene yshyl8A of the family 8 polysaccharide lyase (PL8) was cloned from the genome of Yersinia sp. 298 and subjected to recombinant expression. The specific activity of the recombinase YsHyl8A was 11.19 U/mg, with an optimal reaction temperature of 40 °C and 50% of its specific activity remaining after thermal incubation at 30 °C for 1 h. In addition, its optimal reaction pH was 7.5, and while it was most stable at pH 6.0 in Na2HPO4-citric acid buffer, it remained highly stable at pH 6.0–11.0. Further, its enzymatic activity was increased five-fold with 0.1 M NaCl. YsHyl8A, as an endo-lyase, can degrade both HA and CS, producing disaccharide end-products. These properties suggested that YsHyl8A possessed both significant alkalophilic and cold-adapted features while being dependent on NaCl, likely resulting from its marine source. Yersinia is a typical fish pathogen, with glycosaminoglycan lyase (GAG lyase) as a potential pathogenic factor, exhibiting strong hyaluronidase and chondroitinase activity. Further research on the pathogenic mechanism of GAG lyase may benefit the prevention and treatment of related diseases.

A Highly Active Chondroitin Sulfate Lyase ABC for Enzymatic Depolymerization of Chondroitin Sulfate

Enzymatic preparation of low-molecular-weight chondroitin sulfate (LMWCS) has received increasing attention. In this work, a chondroitin sulfate lyase ABC (Chon-ABC) was successfully cloned, expressed, and characterized. The K_m and V_max of the Chon-ABC were 0.54 mM and 541.3 U mg⁻¹, respectively. The maximal activity was assayed as 500.4 U mg⁻¹ at 37 °C in pH 8.0 phosphate buffer saline. The half-lives of the Chon-ABC were 133 d and 127 min at 4 °C and 37 °C, respectively. Enzymatic preparation of LMWCS was performed at room temperature for 30 min. The changes between the substrate and product were analyzed with mass spectrometry (MS), high-performance liquid chromatography (HPLC), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR). Overall, the Chon-ABC from Bacteroides thetaiotaomicron is competitive in large-scale enzymatic preparation of LMWCS for its high activity, stability, and substrate specificity.

Engineering a thermostable chondroitinase for production of specifically distributed low-molecular-weight chondroitin sulfate

Chondroitinase ABC I (csABC I) has attracted intensive attention because of its great potential in heparin refining and the enzymatic preparation of low-molecular-weight chondroitin sulfate (LMW-CS). However, low thermal resistance (<30℃) restricts its applications. Herein, structure-guided and sequence-assisted combinatorial engineering approaches were applied to improve the thermal resistance of Proteus vulgaris csABC I. By integrating the deletion of the flexible fragment R166-L170 at the N-terminal domain and the mutation of E694P at the C-terminal domain, variant NΔ5/E694P exhibited 247-fold improvement of its half-life at 37℃ and a 2.3-fold increase in the specific activity. Through batch fermentation in a 3-L fermenter, the expression of variant NΔ5/E694P in an Escherichia coli host reached 1.7 g L^-1 with the activity of 1.0 × 10⁵ U L^-1 . Finally, the enzymatic approach for the preparation of LMW-CS was established. By modulating enzyme concentration and controlling depolymerization time, specifically distributed LMW-CS (7000, 3400, and 1900 Da) with low polydispersity was produced, demonstrating the applicability of these processes for the industrial production of LMW-CS in a more environmentally friendly way.

Recent advances in nanotherapeutic strategies for spinal cord injury repair

Spinal cord injury (SCI) is a devastating and complicated condition with no cure available. The initial mechanical trauma is followed by a secondary injury characterized by inflammatory cell infiltration and inhibitory glial scar formation. Due to the limitations posed by the blood-spinal cord barrier, systemic delivery of therapeutics is challenging. Recent development of various nanoscale strategies provides exciting and promising new means of treating SCI by crossing the blood-spinal cord barrier and delivering therapeutics. As such, we discuss different nanomaterial fabrication methods and provide an overview of recent studies where nanomaterials were developed to modulate inflammatory signals, target inhibitory factors in the lesion, and promote axonal regeneration after SCI. We also review emerging areas of research such as optogenetics, immunotherapy and CRISPR-mediated genome editing where nanomaterials can provide synergistic effects in developing novel SCI therapy regimens, as well as current efforts and barriers to clinical translation of nanomaterials.

A novel protein purification strategy mediated by the combination of CipA and Ssp DnaB intein

Protein purification is an indispensable step in diverse fields of biological research or production process. Conventional purification methods including the affinity purification or the usage of self-aggregating tags suffered from many drawbacks such as the complicated steps, high cost and low efficiency. Moreover, the fusion tag usually had negative effects on the activity of the target protein. To address the above issues, here we propose a novel protein purification method which needs simple operation steps, and this method is mediated by the combination of CipA protein and a mini-intein (Synechocystis sp. PCC6803 DnaB, Ssp DnaB), depending on the assembly function of CipA and the self-cleavage function of Ssp DnaB. To realize the purification, CipA-DnaB-eGFP protein was expressed and assembled into protein crystalline inclusions (PCIs) in E. coli. Then, only cell lysis, cleavage and centrifugation steps were required to purify eGFP. Purified eGFP was in the supernatant with a purity of over 90%. The cleavage efficiency and the yield of eGFP reached 51.96% and 13.99 ± 0.88 mg/L fermentation broth, respectively. Furthermore, to broaden the application of this approach, three other proteins which were maltose binding protein (MBP), ketoisovalerate decarboxylase (Kivd) and alcohol dehydrogenase (AdhP) were purified with high cleavage efficiency. The purified Kivd and AdhP remained high specific activities. This work demonstrated an effective and convenient protein purification method.

Chondroitin Sulfate-Degrading Enzymes as Tools for the Development of New Pharmaceuticals

Chondroitin sulfates are linear anionic sulfated polysaccharides found in biological tissues, mainly within the extracellular matrix, which are degraded and altered by specific lyases depending on specific time points. These polysaccharides have recently acquired relevance in the pharmaceutical industry due to their interesting therapeutic applications. As a consequence, chondroitin sulfate (CS) lyases have been widely investigated as tools for the development of new pharmaceuticals based on these polysaccharides. This review focuses on the major breakthrough represented by chondroitin sulfate-degrading enzymes and their structures and mechanisms of function in addition to their major applications.

Enzyme activity enhancement of chondroitinase ABC I from Proteus vulgaris by site-directed mutagenesis

Arg660 was found as a new active site and Asn795Ala and Trp818Ala mutants showed higher activities than the wild type based on molecular docking simulation analysis for the first time.