A novel esterase from Ralstonia sp. M1: gene cloning, sequencing, high-level expression and characterization

Molecular study on recombinant cold-adapted, detergent- and alkali stable esterase (EstRag) from Lysinibacillus sp.: a member of family VI

Cold-adapted esterases have potential industrial applications. To fulfil the global continuous demand for these enzymes, a cold-adapted esterase member of family VI from Lysinibacillus sp. YS11 was cloned on pET-28b (+) vector and expressed in E. coli BL21(DE3) Rosetta cells for the first time. The open reading frame (654 bp: GenBank MT120818.1) encodes a polypeptide (designated EstRag: 217 amino acid residues). EstRag amino acid sequence has conserved esterase signature motifs: pentapeptide (GFSQG) and catalytic triad Ser¹¹⁰-Asp¹⁶³-His¹⁹⁴. EstRag 3D predicted model, built with LOMETS3 program, showed closest structural similarity to PDB 1AUO_A (esterase: Pseudomonas fluorescens); TM-align score program inferences. Purified EstRag to 9.28-fold, using Ni²⁺affinity agarose matrix, showed a single protein band (25 kDa) on SDS-PAGE, Km (0.031 mM) and Kcat/Km (657.7 s⁻¹ mM⁻¹) on p-NP-C2. Temperature and pH optima of EstRag were 35 °C and 8.0, respectively. EstRag was fully stable at 5–30 °C for 120 min and at pH(s) 8.0–10.0 after 24 h. EstRag activity (391.46 ± 0.009%) was impressively enhanced after 30 min preincubation with 5 mM Cu²⁺. EstRag retained full stability after 30 min pre-incubation with 0.1%(v/v) SDS, Triton X-100, and Tween-80. EstRag promising characteristics motivate performing guided evolution and industrial applications prospective studies.

Discovery of α-Glucosidase Inhibitors from Marine Microorganisms: Optimization of Culture Conditions and Medium Composition

Various studies showed that the suppression of α-glucosidase activity can impede the glucose absorption in our body, and therefore, it can be used to treat type 2 diabetes. Hence, the compounds with anti-α-glucosidase have gained considerable attention because of their potential application in diabetes treatment. In previous literature studies, these anti-α-glucosidase compounds were extracted from plants and fungus. Less studies are being conducted to identify the anti-α-glucosidase compounds in the microbial community. In this study, 23 marine bacterial strains were screened for their potential to suppress the α-glucosidase activity. The highest inhibitory activity was exhibited by isolated L06 which was identified as Oceanimonas smirnovii EBL6. The cultivation conditions, such as temperature and pH, were optimized to increase the production of α-glucosidase inhibitors by Oceanimonas smirnovii EBL6 strain. The result findings showed that the highest yield of α-glucosidase inhibitors can be obtained at the culture time of 120 h, fermentation temperature of 30 °C, and pH 4.6. Under these conditions, the inhibitory activity of α-glucosidase can reach 81%. The IC₅₀ of n-butanol extract was 13.89 μg/ml, while standard acarbose was 31.16 μg/ml. Overall, these findings suggest that Oceanimonas smirnovii produces α-glucosidase inhibitors and could been applied in the biochemical and medicinal fields in the future.

High-level expression, purification and properties of an Endochitinase gene without signal peptide from Lecanicillium lecanii 43H in Pichia pastoris

Chitinases play the key role in hydrolysis of chitin, a huge organic carbon reservoir on earth, into monomeric sugars and their eventual conversion into valuable chemicals and energy sources. The Lecanicillium lecanii strain 43H was used as the source for the Endochitinase gene without signal peptide (mchit1). This mchit1 gene was cloned and sequenced. The recombinant Endochitinase non signal peptide was overexpressed in Pichia pastoris X33 with a level of 2.048 U mL^-1 culture supernatant. The molecular mass of the purified recombinant Endochitinase (rmchit1) without signal peptide was 43 kDa. Metal ions, detergents, and organic solvents tested indicated a significantly influence on rmchit1 activity. The obtained results demonstrated that signal peptides affect the yield expression, purification methods, recovery as well as the physicochemical properties of the enzyme.

Purification, gene cloning, and characterization of a novel halohydrin dehalogenase from Agromyces mediolanus ZJB120203

A novel halohydrin dehalogenase (HHDH), catalyzing the transformation of 1,3-dichloro-2-propanol (1,3-DCP) to epichlorohydrin (ECH), was purified from Agromyces mediolanus ZJB120203. The molecular mass of the enzyme was estimated to be 28 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A 735-bp nucleotide fragment was obtained based on the N-terminal and internal amino acid sequences of the purified HHDH. The gene codes a protein sequence with 244 amino acid residues, and the protein sequence shows high similarity to Hhe AAD2 (HHDH from Arthrobacter sp. AD2), defined as Hhe AAm, which is the seventh reported HHDH. Expression of Hhe AAm was carried out in Escherichia coli and purification was performed by nickel-affinity chromatography. The recombinant HheAAm possessed an optimal pH of 8.5 and an optimal temperature of 50 °C and manifested a K m of 4.58 mM and a V max of 3.84 μmol/min(/)mg. The activity of Hhe AAm was not significantly affected by metal ions such as Zn(2+), Ca(2+), Cu(2+), and EDTA, but was strongly inhibited by Hg(2+) and Ag(+). In particular, the Hhe AAm exhibits an enantioselectivity for the conversion of prochiral 1,3-DCP to (S)-ECH. The applications of the Hhe AAm as a catalyst for asymmetric synthesis are promising.

Highly effective renaturation of a streptokinase from Streptococcus pyogenes DT7 as inclusion bodies overexpressed in Escherichia coli

The streptokinase (SK) is emerging as an important thrombolytic therapy agent in the treatment of patients suffering from cardiovascular diseases. We reported highly effective renaturation of a SK from S. pyogeness DT7 overexpressed in E. coli, purification, and biochemical characterization. A gene coding for the SK was cloned from S. pyogeness DT7. Because accumulation of active SK is toxic to the host cells, we have expressed it in the form of inclusion bodies. The mature protein was overexpressed in E. coli BL21 DE3/pESK under the control of the strong promoter tac induced by IPTG with a level of 60% of the total cell proteins. The activity of the rSK, renatured in phosphate buffer supplemented with Triton X-100 and glycerol, was covered with up to 41 folds of its initial activity. The purified of protein was identified with MALDI-TOF mass spectrometry through four peptide fragments, which showed 100% identification to the corresponding peptides of the putative SK from GenBank. Due to overexpression and highly effective renaturation of large amounts of inclusion bodies, the recombinant E. coli BL21 DE3/pESK system could be potentially applied for large-scale production of SK used in the therapy of acute myocardial infarction.

Isolation and characterization of a heavy metal-resistant, thermophilic esterase from a Red Sea brine pool

The Red Sea Atlantis II brine pool is an extreme environment that displays multiple harsh conditions such as high temperature, high salinity and high concentrations of multiple, toxic heavy metals. The survival of microbes in such an environment by utilizing resistant enzymes makes them an excellent source of extremophilic enzymes. We constructed a fosmid metagenomic library using DNA isolated from the deepest and most secluded layer of this pool. We report the isolation and biochemical characterization of an unusual esterase: EstATII. EstATII is thermophilic (optimum temperature, 65°C), halotolerant (maintains its activity in up to 4.5 M NaCl) and maintains at least 60% of its activity in the presence of a wide spectrum of heavy metals. The combination of biochemical characteristics of the Red Sea Atlantis II brine pool esterase, i.e., halotolerance, thermophilicity and resistance to heavy metals, makes it a potentially useful biocatalyst.

Cloning and enhancing production of a detergent- and organic-solvent-resistant nattokinase from Bacillus subtilis VTCC-DVN-12-01 by using an eight-protease-gene-deficient Bacillus subtilis WB800

Background

Nattokinases/Subtilisins (EC 3.4.21.62) belong to the second large family of serine proteases, which gain significant attention and play important role in many biotechnology processes. Thus, a number of nattokinases/subtilisins from various Bacillus species, especially from B. subtilis strains, extensively have been investigated to understand their biochemical and physical properties as well as to improve the production for industrial application. The purpose of this study was to clone a nattokinase gene from Bacillus subtilis strain VTCC-DVN-12-01, enhance its production in B. subtilis WB800, which is deficient in eight extracellular proteases and characterize its physicochemical properties for potential application in organic synthesis and detergent production.

Results

A gene coding for the nattokinase (Nk) from B. subtilis strain VTCC-DVN-12-01 consisted of an ORF of 1146 nucleotides, encoding a pre-pro-protein enzyme (30-aa pre-signal peptide, 76-aa pro-peptide and 275-aa mature protein with a predicted molecular mass of 27.7 kDa and pI 6.6). The nattokinase showed 98-99% identity with other nattokinases/subtilisins from B. subtilis strains in GenBank. Nk was expressed in B. subtilis WB800 under the control of acoA promoter at a high level of 600 mg protein per liter culture medium which is highest yield of proteins expressed in any extracellular-protease-deficient B. subtilis system till date. Nk was purified to homogeneity with 3.25 fold purification, a specific activity of 12.7 U/mg, and a recovery of 54.17%. The purified Nk was identified by MALDI-TOF mass spectrometry through three peptides, which showed 100% identity to corresponding peptides of the B. subtilis nattokinase (CAC41625). An optimal activity for Nk was observed at 65°C and pH 9. The nattokinase was stable at temperature up to 50°C and in pH range of 5–11 and retained more than 85% of its initial activity after incubation for 1 h. Mg²⁺ activated Nk up to 162% of its activity. The addition of Triton X-100, Tween 20, and Tween 80 showed an activation of Nk up to 141% of its initial activity but SDS strongly inhibited. The enzyme was highly resistant to organic solvents.

Conclusions

Our findings demonstrated that an eight-protease-gene-deficient Bacillus subtilis WB800 could overproduce the nattokinase from B. subtilis VTCC-DVN-12-01. Due to high resistance to detergents and organic solvents of this nattokinase, it could be potentially applied in organic synthesis and detergent production.

Enhancing functional production of a chaperone-dependent lipase in Escherichia coli using the dual expression cassette plasmid

BACKGROUND

The lipase subfamilies I.1 and I.2 show more than 33% homology in the amino acid sequences and most members share another common property that their genes are clustered with the secondary genes whose protein products are required for folding the lipase into an active conformation and secretion into the culture medium. In previous studies, the lipase (LipA) and its chaperone (LipB) from Ralstonia sp. M1 were overexpressed in E. coli and the lipase was successfully refolded in vitro. The purpose of this study was to enhance the production of the active lipase LipA from Ralstonia sp. M1 in the heterologous host E. coli without in vitro refolding process, using two-plasmid co-expression systems and dual expression cassette plasmid systems.

RESULTS

To produce more active lipase from Ralstonia sp. M1 in E. coli without in vitro refolding process but with the help of overexpression of the chaperone (LipB1 and LipB3 corresponding to 56-aa truncated and 26-aa truncated chaperone LipB), six different expression systems including 2 two-plasmid co-expression systems (E. coli BL21/pELipABa + pELipB1k and BL21/pELipABa + pELipB3k) and 4 dual expression cassette plasmid systems (BL21/pELipAB-LipB1a, BL21/pELipAB-LipB3a, BL21/pELipA-LipB1a, and BL21/pELipA-LipB3a) were constructed. The two-plasmid co-expression systems (E. coli BL21/pELipABa + pELipB1k and BL21/pELipABa + pELipB3k) produced the active lipase at a level of 4 times as high as the single expression cassette plasmid system E. coli BL21/pELipABa did. For the first time, the dual expression cassette plasmid systems BL21/pELipAB-LipB1a and BL21/pELipAB-LipB3a yielded 29- and 19-fold production of the active lipase in comparison with the single expression cassette plasmid system E. coli BL21/pELipABa, respectively. Although the lipase amount was equally expressed in all these expression systems (40% of total cellular protein) and only a small fraction of the overexpressed lipase was folded in vivo into the functional lipase in soluble form whereas the main fraction was still inactive in the form of inclusion bodies. Another controversial finding was that the dual expression cassette plasmid systems E. coli BL21/pELipAB-LipB1a and E. coli/pELipAB-LipB3a secreted the active lipase into the culture medium of 51 and 29 times as high as the single expression cassette plasmid system E. coli pELipABa did, respectively, which has never been reported before. Another interesting finding was that the lipase form LipA6xHis (mature lipase fused with 6× histidine tag) expressed in the dual expression cassette plasmid systems (BL21/pELipA-LipB1a and BL21/pELipA-LipB3a) showed no lipase activity although the expression level of the lipase and two chaperone forms LipB1 and LipB3 in these systems remained as high as that in E. coli BL21/pELipABa + pELipB1k, BL21/pELipABa + pELipB3k, BL21/pELipAB-LipB1a, and BL21/pELipAB-LipB3a. The addition of Neptune oil or detergents into the LB medium increased the lipase production and secretion by up to 94%.

CONCLUSIONS

Our findings demonstrated that a dual expression cassette plasmid system E. coli could overproduce and secrete the active chaperone-dependent lipase (subfamilies I.1 and I.2) in vivo and an improved dual expression cassette plasmid system E. coli could be potentially applied for industrial-scale production of subfamily I.1 and I.2 lipases.

Characterization of the Recombinant Thermostable Lipase (Pf2001) from Pyrococcus furiosus: Effects of Thioredoxin Fusion Tag and Triton X-100

In this work, the lipase from Pyrococcus furiosus encoded by ORF PF2001 was expressed with a fusion protein (thioredoxin) in Escherichia coli. The purified enzymes with the thioredoxin tag (TRX−PF2001Δ60) and without the thioredoxin tag (PF2001Δ60) were characterized, and various influences of Triton X-100 were determined. The optimal temperature for both enzymes was 80°C. Although the thioredoxin presence did not influence the optimum temperature, the TRX−PF2001Δ60 presented specific activity twice lower than the enzyme PF2001Δ60. The enzyme PF2001Δ60 was assayed using MUF-acetate, MUF-heptanoate, and MUF-palmitate. MUF-heptanoate was the preferred substrate of this enzyme. The chelators EDTA and EGTA increased the enzyme activity by 97 and 70%, respectively. The surfactant Triton X-100 reduced the enzyme activity by 50% and lowered the optimum temperature to 60°C. However, the thermostability of the enzyme PF2001Δ60 was enhanced with Triton X-100.