Recombinant expression and characterization of the Candida rugosa lip4 lipase in Pichia pastoris: comparison of glycosylation, activity, and stability

Microplate spectrophotometric method for regioselective lipase screening using structured triglycerides with punicic acid as probe

In this study, we propose a continuous assay that provides a high-throughput, efficient method for screening the regioselectivity of lipases at the sn-1,3 and sn-2 positions on triacylglycerols (TAGs). This assay measures the specific hydrolysis rates at the primary and secondary positions of TAGs derivates containing oleic (O) and punicic (P) acids. The method is based on the absorbance ratio of released punicic acid from the hydrolysis of sn-POP (sn-1,3 regiospecific lipases) and sn-OPO (sn-2 regiospecific lipases). The method was validated using pure lipases with known and unknown regioselectivity. Unexpectedly, we found that recombinant Lipase 4 from Candida rugosa (rCRLip4) exhibited significant sn-2 regioselectivity, indicating greater regioselectivity than recombinant lipase A from Candida antarctica (rCALA). In silico analysis and molecular docking studies were conducted to elucidate the main structural differences between CRLip4 and the non-regioselective isoform CRLip1. This continuous regioselective lipase assay on TAGs is versatile and can be used to screen for sn-1,3, sn-2 or non-regioselective lipases. It holds significant potential applications in the biocatalytic production of structured lipids and other industrial processes where regioselectivity is crucial.

Selective synthesis of triacylglycerols by the ADS-17-supported Candida antarctica lipase B through esterification of oleic acid and glycerol

BACKGROUND

Immobilized enzyme possessing both high activity and good selectivity is important in practice. In this study, Candida antarctica lipase B (CALB) was immobilized onto the macroporous resin ADS-17 for triacylglycerol (TAG) synthesis through esterification of oleic acid and glycerol. The reaction conditions were optimized by single-factor study and orthogonal test, and the reusability of the immobilized CALB (CALB@ADS-17) was evaluated. In addition, the mechanism of lipase immobilization was studied and the catalytic mechanism of CALB@ADS-17 was investigated.

RESULTS

Oleic acid conversion up to 99.20% and TAG content at 91.58 wt% could be obtained under optimal conditions. In addition, the CALB@ADS-17 retained 84.28% of its initial activity after 11 cycles of reuse. The mechanism of lipase immobilization was through hydrophobic adsorption. The relationship between temperature and oleic acid conversion was lnV0 = 6.3316 - 4.3321/T, and the activation energy (Ea) was 36.02 kJ mol-1. CALB@ADS-17 did not exhibit an obvious interfacial activation phenomenon. Its kinetic behavior can be described by the Michaelis-Menten model, whose kinetic parameters of vmax, kcat, Km, Ki, and kcat/Km were 0.01265 μmol L-1 s-1, 9310.72 s-1, 0.4907 mmol L-1, 3.997 mmol L-1, and 1.90 × 104 L mmol-1 s-1, respectively.

CONCLUSION

CALB@ADS-17 showed good esterification performance and exhibited good selectivity towards TAG generation. In addition, CALB@ADS-17 exhibited good reusability in esterification reactions and has potential in practical applications. © 2025 Society of Chemical Industry.

Co-expression of Pseudomonas alcaligenes lipase and its specific foldase in Pichia pastoris by a dual expression cassette strategy

Lipomax is a commercialized foldase-dependent Pseudomonas lipase that was previously expressed only in Pseudomonas strains. Here, using Pichia pastoris as the host, we report a new co-expression method that leads to the successful production of Lipomax. The active Lipomax is extracellularly co-expressed with its cognate foldase (LIM); and the purified enzyme mix has the optimum pH at pH 8.0 and an optimal temperature around 40 °C. N-glycosylation was observed for Pichia produced Lipomax, and its reduction was shown to increase the lipolytic activity. With different p-nitrophenyl esters as the substrates, the substrate profiling analyses further indicate that Lipomax prefers esters with middle-long chain fatty acids, showing the highest specific activity to p-nitrophenyl caprylate (C8). The extracellular co-expression of Lipomax and LIM in Pichia will not only increase our ability to investigate additional eukaryotic hosts for lipase expression, but also be of considerable value in analyzing other foldase-dependent lipases.

Biochemical Characterization of a Lipolytic Enzyme From Aspergillus oryzae That Hydrolyzes Triacylglycerol and Sterol Esters

A novel lipolytic enzyme-encoding gene, lipO745, from Aspergillus oryzae RIB40 was cloned and expressed in Pichia pastoris. Purified recombinant LipO745 (rLipO745) had a molecular mass of approximately 60 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. rLipO745 exhibited maximum activity at 40 °C and pH 7.0 and was stable at temperatures ≤ 40 °C. The substrate specificity of purified rLipO745 was analyzed using α-naphthyl esters as artificial substrates and various triacylglycerol and sterol esters as natural substrates. From among a panel of α-naphthyl esters (C2-C16), α-naphthyl butyrate (C4), with an activity of 269 ± 3.3 units/mg protein, was the optimal substrate for hydrolysis by the purified recombinant protein. The K_m and k_cat values of rLiO745 for the C4 substrate were 0.073 ± 0.0012 mM and 608 ± 108 s^-1, respectively. The purified recombinant enzyme had considerable hydrolytic activity toward tributyrin, tripalmitin, and triolein, indicating lipase activity, and toward cholesteryl acetate, butyrate, palmitate, and oleate, indicating sterol esterase activity. Transesterification activities between tributyrin and cholesterol or between tributyrin and campesterol were also determined.

Contribution of the Oligomeric State to the Thermostability of Isoenzyme 3 from Candida rugosa

Thermophilic proteins have evolved different strategies to maintain structure and function at high temperatures; they have large, hydrophobic cores, and feature increased electrostatic interactions, with disulfide bonds, salt-bridging, and surface charges. Oligomerization is also recognized as a mechanism for protein stabilization to confer a thermophilic adaptation. Mesophilic proteins are less thermostable than their thermophilic homologs, but oligomerization plays an important role in biological processes on a wide variety of mesophilic enzymes, including thermostabilization. The mesophilic yeast Candida rugosa contains a complex family of highly related lipase isoenzymes. Lip3 has been purified and characterized in two oligomeric states, monomer (mLip3) and dimer (dLip3), and crystallized in a dimeric conformation, providing a perfect model for studying the effects of homodimerization on mesophilic enzymes. We studied kinetics and stability at different pHs and temperatures, using the response surface methodology to compare both forms. At the kinetic level, homodimerization expanded Lip3 specificity (serving as a better catalyst on soluble substrates). Indeed, dimerization increased its thermostability by more than 15 °C (maximum temperature for dLip3 was out of the experimental range; >50 °C), and increased the pH stability by nearly one pH unit, demonstrating that oligomerization is a viable strategy for the stabilization of mesophilic enzymes.

Comparison of Candida antarctica Lipase B Variants for Conversion of ε-Caprolactone in Aqueous Medium-Part 2

Enzyme-catalyzed ring-opening polymerization of lactones is a method of increasing interest for the synthesis of polyesters. In the present work, we investigated which changes in the structure of Candida antarctica lipase B (CaLB) shift the catalytic equilibrium between esterification and hydrolysis towards polymerization. Therefore, we present two concepts: (i) removing the glycosylation of CaLB to increase the surface hydrophobicity; and (ii) introducing a hydrophobic lid adapted from Pseudomonas cepacia lipase (PsCL) to enhance the interaction of a growing polymer chain to the elongated lid helix. The deglycosylated CaLB (CaLB-degl) was successfully generated by site-saturation mutagenesis of asparagine 74. Furthermore, computational modeling showed that the introduction of a lid helix at position Ala148 was structurally feasible and the geometry of the active site remained intact. Via overlap extension PCR the lid was successfully inserted, and the variant was produced in large scale in Pichia pastoris with glycosylation (CaLB-lid) and without (CaLB-degl-lid). While the lid variants show a minor positive effect on the polymerization activity, CaLB-degl showed a clearly reduced hydrolytic and enhanced polymerization activity. Immobilization in a hydrophobic polyglycidol-based microgel intensified this effect such that a higher polymerization activity was achieved, compared to the "gold standard" Novozym® 435.

Heterologous overexpression and biochemical characterization of the (galactophospho)lipase from Fusarium solani in Pichia pastoris that is expressed in planta

High-level extracellular production of Fusarium solani (galactophospho)lipase, named FSL, was achieved using a Pichia pastoris X33 expression system. The (galactophospho) lipase encoding gene was cloned into pGAPZαA with the Saccharomyces cerevisiae α-factor signal sequence by two different ways. The two constructs consist of an additional sequence of a (His)6-tag of the vector fused to the N-terminus of this enzyme (tFSL) while the other expression vector was constructed without any additional sequence (rFSL). Compared to the native enzyme (nFSL) (18.75 mg/L), a high level secretion of rFSL (310 mg/L) and tFSL (240 mg/L) was achieved providing an important improvement in enzyme production. Biochemical characterization showed that pure recombinant proteins (rFSL and tFSL) presented similar behaviour towards triglycerides, phospholipid and galactolipid. Like the nFSL, rFSL and tFSL are active at high concentration of bile salts (4mM) and calcium ions enhanced lipase activity. During plant infection, transcripts of this fungal lipase gene were detected 3, 7 and 10 days post infection.

Conversion of crude Jatropha curcas seed oil into biodiesel using liquid recombinant Candida rugosa lipase isozymes

The versatile Candida rugosa lipase (CRL) has been widely used in biotechnological applications. However, there have not been feasibility reports on the transesterification of non-edible oils to produce biodiesel using the commercial CRL preparations, mixtures of isozymes. In the present study, four liquid recombinant CRL isozymes (CRL1-CRL4) were investigated to convert various non-edible oils into biodiesel. The results showed that recombinant CRL2 and CRL4 exhibited superior catalytic efficiencies for producing fatty acid methyl ester (FAME) from Jatropha curcas seed oil. A maximum 95.3% FAME yield was achieved using CRL2 under the optimal conditions (50 wt% water, an initial 1 equivalent of methanol feeding, and an additional 0.5 equivalents of methanol feeding at 24h for a total reaction time of 48 h at 37 °C). We concluded that specific recombinant CRL isozymes could be excellent biocatalysts for the biodiesel production from low-cost crude Jatropha oil.

Modulation of the thermostability and substrate specificity of Candida rugosa lipase1 by altering the acyl-binding residue Gly414 at the α-helix-connecting bend

Candida rugosa Lipase1 (LIP1) is widely used in industrial applications. Optimizing its catalytic performance is still a challenging goal for protein engineers. Mutagenesis of key residues in the active site of the enzyme may provide an effective strategy for enhancing stability and altering substrate specificity. In this study, multiple sequence alignment and structural analysis revealed that the acyl-binding residue, Gly414, of LIP1, which is located at a bend connecting α-helixes, was the non-conserved residue in five other isoenzymes. Using saturation mutagenesis, four mutants with improved stability (G414A, G414M, G414H and G414W) were obtained. Compared to the wild type, the best mutant (G414W) exhibited a remarkable 6.5-fold enhancement in half-life at 60 °C and a 14 °C higher T50(15). Its optimum temperature was increased by 15 °C. Simultaneously, G414W displayed a shift in substrate preference from medium-chain to short-chain pNP-ester. Modeling analysis showed that the multiple interactions formed by hydrophobic clusters and hydrogen bonds in the acyl-binding tunnel might lead to the observed thermostability improvement. Additionally, the bulky tryptophan substitution formed a strong steric hindrance to the accommodation of long-chain substrates in the tunnel. These results indicate that the key acyl-binding residues at the α-helix-connecting bend could mediate enzyme stability and catalytic substrate spectra.

Partial optimization of the 5-terminal codon increased a recombination porcine pancreatic lipase (opPPL) expression in Pichia pastoris

Pancreatic lipase plays a key role in intestinal digestion of feed fat, and is often deficient in young animals such as weaning piglets. The objective of this study was to express and characterize a partial codon optimized porcine pancreatic lipase (opPPL). A 537 bp cDNA fragment encoding N-terminus amino acid residue of the mature porcine pancreatic lipase was synthesized according to the codon bias of Pichia pastoris and ligated to the full-length porcine pancreatic lipase cDNA fragment. The codon optimized PPL was cloned into the pPICZαA (Invitrogen, Beijing, China) vector. After the resultant opPPL/pPICZαΑ plasmid was transformed into P.pastoris, the over-expressed extracellular opPPL containing a His-tag to the C terminus was purified using Ni Sepharose affinity column (GE Healthcare, Piscataway, NJ, USA), and was characterized against the native enzyme (commercial PPL from porcine pancreas, Sigma). The opPPL exhibited a molecular mass of approximately 52 kDa, and showed optimal temperature (40°C), optimal pH (8.0), K_m (0.041 mM), and V_max (2.008 µmol.mg protein ⁻¹.min⁻¹) similar to those of the commercial enzyme with p-NPP as the substrate. The recombinant enzyme was stable at 60°C, but lost 80% (P<0.05) of its activity after exposure to heat ≥60°C for 20 min. The codon optimization increased opPPL yield for ca 4 folds (146 mg.L⁻¹ vs 36 mg.L⁻¹) and total enzyme activity increased about 5 folds (1900 IU.L⁻¹ vs 367 IU.L⁻¹) compared with those native naPPL/pPICZαΑ tranformant. Comparison of gene copies and mRNA profiles between the two strains indicated the increased rePPL yields may partly be ascribed to the increased protein translational efficiency after codon optimization. In conclusion, we successfully optimized 5-terminal of porcine pancreatic lipase encoding gene and over-expressed the gene in P. pastoris as an extracellular, functional enzyme. The recombination enzyme demonstrates a potential for future use as an animal feed additive for animal improvement.

Characterization of an N-glycosylated Bacillus subtilis leucine aminopeptidase expressed in Pichia pastoris

Aminopeptidase is an important flavorsome especially in protein hydrolysate debittering by removing hydrophobic amino acid residue at the N-terminal end. Besides, it is also applied to preparation of active peptides and analysis of protein sequence. In this study, leucine aminopeptidase from Bacillus subtilis was cloned and expressed in Pichia pastoris, a widely used heterologous protein expression host. Then it was purified and characterized. After methanol induction for 96 h, the aminopeptidase activity in culture supernatant reached 28.4 U ml(À1) , which was 7.1 times that of wild strain B. subtilis Zj016. The optimal temperature and pH of the purified recombinant enzyme were 60 °C and 8.5, respectively. The purified aminopeptidase was stable within 30-60 °C and pH 8.0-9.0. It was intensively inhibited by Ni(2β) , Ca(2β) , DL-dithiothreitol (DTT) and ethylene diamine tetraacetic acid (EDTA), but activated by Co(2β) . The Km toward leucine-p-nitroanilines (Leu-pNA) of the enzyme was 0.97 mM. The sequence analysis of aminopeptidase indicated three potential N-glycosylation sites and it was further verified via MALDI-TOF-MS analysis. Consequently, the N-glycosylated aminopeptidase exhibited higher thermostability and catalytic efficiency. The purified enzyme exhibited two bands through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) while a single band can be identified when the enzyme was deglycosylated. Circular dichroism spectroscopy indicated that the secondary structure of recombinant aminopeptidase was similar to the wild-type.

Expression of a Deschampsia antarctica Desv. polypeptide with lipase activity in a Pichia pastoris vector

The current study isolated and characterized the Lip3F9 polypeptide sequence of Deschampsia antarctica Desv. (GeneBank Accession Number JX846628), which was found to be comprised of 291 base pairs and was, moreover, expressed in Pichia pastoris X-33 cells. The enzyme was secreted after 24 h of P. pastoris culture incubation and through induction with methanol. The expressed protein showed maximum lipase activity (35 U/L) with an optimal temperature of 37 °C. The lipase-expressed enzyme lost 50% of its specific activity at 25 °C, a behavior characteristic of a psychrotolerant enzyme. Recombinant enzyme activity was measured in the presence of ionic and non-ionic detergents, and a decrease in enzyme activity was detected for all concentrations of ionic and non-ionic detergents assessed.

The role of N-glycosylation sites in the activity, stability, and expression of the recombinant elastase expressed by Pichia pastoris

The Pseudomonas aeruginosa elastase (PAE), produced by Pseudomonas aeruginosa (P. aeruginosa), is a promising biocatalyst for peptide synthesis in organic solvents. As P. aeruginosa is an opportunistic pathogen, the enzyme has been heterologously over-expressed in the safe and efficient host, Pichia pastoris (P. pastoris) for its industrial application. The recombinant elastase (rPAE) contains three potential N-glycosylation sites (Asn-Xaa-Ser/Thr consensus sequences), and is heterogeneously N-glycosylated. To investigate the role of N-glycosylation in the activity, stability, and expression of rPAE, these potential N-glycosylation sites (N43, N212, and N280) were mutated using site-directed mutagenesis. Specifically the asparagine (Asn, N) residues were converted to glutamine (Gln, Q). The enzymatic activity and stability of non-glycosylated and glycosylated rPAE were then compared. The results indicated that the influence of N-glycosylation on its activity was insignificant. The non- and glycosylated isoforms of rPAE displayed similar kinetic parameters for hydrolyzing casein in aqueous medium, and when catalyzing bipeptide synthesis in 50% (v/v) DMSO, they exhibited identical substrate specificity and activity, and produced similar yields. However, N-glycosylation improved rPAE stability both in aqueous medium and in 50% (v/v) organic solvents. The half-lives of the glycosylated and non-glycosylated forms of rPAE at 70°C were 32.2 and 23.1 min, respectively. Mutation of any potential N-glycosylation site was detrimental to its expression in P. pastoris. There was a 23.9% decrease in expression of the N43Q mutant, 63.6% of the N212Q mutant, and 63.7% of the N280Q mutant compared with the wild type. Furthermore, combined mutation of these sites resulted in an additional decrease in the caseinolytic activities of the mutants. These results indicated that all of the N-glycosylation sites were necessary for high-level expression of rPAE.

Enhanced activity of Rhizomucor miehei lipase by deglycosylation of its propeptide in Pichia pastoris

Many studies have demonstrated that the properties of enzymes expressed in eukaryotes can be affected by the position and extent of glycosylation on enzyme. In this study, two potential glycosylation sites (the 8th and the 58th asparagine) were identified and the effect of propeptide glycosylation on Rhizomucor miehei lipase (RML) expressed in Pichia pastoris was investigated. To better understand the effect of glycosylation on the activity of RML, three mutants (M1, generated by N8A; M2, generated by N58A; and M3, generated by N8A and N58A) were designed to generate deglycosylated enzymes. The results showed that deglycosylated RML exhibited a twofold higher activity compared to the wild type. However, it was also found that glycosylation on the propeptide was important for the removal of the propeptide by Kex2 protease and secretion of the enzyme. Thus, our study provided a further understanding into the role of glycosylation on enzyme function.

Recombinant sterol esterase from Ophiostoma piceae: an improved biocatalyst expressed in Pichia pastoris

BACKGROUND

The ascomycete Ophiostoma piceae produces a sterol esterase (OPE) with high affinity towards p-nitrophenol, glycerol and sterol esters. Its hydrolytic activity on natural mixtures of triglycerides and sterol esters has been proposed for pitch biocontrol in paper industry since these compounds produce important economic losses during paper pulp manufacture.

RESULTS

Recently, this enzyme has been heterologously expressed in the methylotrophic yeast Pichia pastoris, and the hydrolytic activity of the recombinant protein (OPE*) studied. After the initial screening of different clones expressing the enzyme, only one was selected for showing the highest production rate. Different culture conditions were tested to improve the expression of the recombinant enzyme. Complex media were better than minimal media for production, but in any case the levels of enzymatic activity were higher (7-fold in the best case) than those obtained from O. piceae. The purified enzyme had a molecular mass of 76 kDa, higher than that reported for the native enzyme under SDS-PAGE (60 kDa). Steady-state kinetic characterization of the recombinant protein showed improved catalytic efficiency for this enzyme as compared to the native one, for all the assayed substrates (p-nitrophenol, glycerol, and cholesterol esters). Different causes for this were studied, as the increased glycosylation degree of the recombinant enzyme, their secondary structures or the oxidation of methionine residues. However, none of these could explain the improvements found in the recombinant protein. N-terminal sequencing of OPE* showed that two populations of this enzyme were expressed, having either 6 or 8 amino acid residues more than the native one. This fact affected the aggregation behaviour of the recombinant protein, as was corroborated by analytical ultracentrifugation, thus improving the catalytic efficiency of this enzyme.

CONCLUSION

P. pastoris resulted to be an optimum biofactory for the heterologous production of recombinant sterol esterase from O. piceae, yielding higher activity levels than those obtained with the saprophytic fungus. The enzyme showed improved kinetic parameters because of its modified N-terminus, which allowed changes in its aggregation behaviour, suggesting that its hydrophobicity has been modified.

Improved production of heterologous lipase in Trichoderma reesei by RNAi mediated gene silencing of an endogenic highly expressed gene

A lipase gene (Lip) of the Aspergillus niger was de novo synthesized and expressed in the Trichoderma reesei under the promoter of the cellobiohydrolase I gene (cbh1). RNAi-mediated gene silencing was successfully used to further improve the recombinant lipase production via down-regulation of CBHI which comprised more than 60% of the total extracellular proteins in T. reesei. The gene and protein expression of CBHI and recombinant lipase were analyzed by real-time PCR, SDS-PAGE and activity assay. The results demonstrated that RNAi-mediated gene silencing could effectively suppress cbh1 gene expression and the reduction of CBHI could result in obvious improvement of heterologous lipase production. The reconstructed strains with decreased CBHI production exhibited 1.8- to 3.2-fold increase in lipase activity than that of parental strain. The study herein provided a feasible and advantageous method of increasing heterologous target gene expression in T. reesei through preventing the high expression of a specific endogenenous gene by RNA interference.

Lipases: an overview

Lipases are ubiquitous enzymes, widespread in nature. They were first isolated from bacteria in the early nineteenth century and the associated research continuously increased due to the particular characteristics of these enzymes. This chapter reviews the main sources, structural properties, and industrial applications of these highly studied enzymes.

Heterologous expression systems for lipases: a review

The production of heterologous lipases is one of the most promising strategies to increase the productivity of the bioprocesses and to reduce costs, with the final objective that more industrial lipase applications could be implemented. In this chapter, an overview of the most common microbial expression systems for the overproduction of microbial lipases is presented. Prokaryotic system as Escherichia coli and eukaryotic systems as Saccharomyces cerevisiae and Pichia pastoris are analyzed and compared in terms of productivity, operational, and downstream processing facilities. Finally, an overview of heterologous Candida rugosa and Rhizopus oryzae lipases, two of the most common lipases used in biocatalysis, is presented. In both cases, P. pastoris has been shown as the most promising host system.

Optimal production and biochemical properties of a lipase from Candida albicans

Lipases from microorganisms have multi-faceted properties and play an important role in ever-growing modern biotechnology and, consequently, it is of great significance to develop new ones. In the present work, a lipase gene from Candida albicans (CaLIP10) was cloned and two non-unusual CUG serine codons were mutated into universal codons, and its expression in Pichia pastoris performed optimally, as shown by response surface methodology. Optimal conditions were: initial pH of culture 6.86, temperature 25.53 °C, 3.48% of glucose and 1.32% of yeast extract. The corresponding maximal lipolytic activity of CaLIP10 was 8.06 U/mL. The purified CaLIP10 showed maximal activity at pH 8.0 and 25 °C, and a good resistance to non-ionic surfactants and polar organic solvent was noticed. CaLIP10 could effectively hydrolyze coconut oil, but exhibited no obvious preference to the fatty acids with different carbon length, and diacylglycerol was accumulated in the reaction products, suggesting that CaLIP10 is a potential lipase for the oil industry.

Engineering the expression and biochemical characteristics of recombinant Candida rugosa LIP2 lipase by removing the additional N-terminal peptide and regional codon optimization

Candida rugosa lipase (CRL), an important industrial enzyme, has been established, containing several different isoforms which were encoded by the high-identity lip gene family (lip1 to lip7). In this study, we compared the expression and biochemical characterization with three different engineered lip2 constructions in the yeast Pichia pastoris. Our results showed that lip2 (lip2) has an overall improvement of 50% higher production yield (1.446 U/mL) relative to that of nflip2 (0.964 U/mL) at 7 days of cultivation time. Codon-optimized lip2 (colip2) has a 2.3-fold higher production yield (2.182 U/mL) compared to that of lip2 (noncodon-optimized; 1.446 U/mL) and nflip2 (0.964 U/mL), with a cultivation time of 5 days. This finding demonstrated that the removal of the N-terminus and the regional codon optimization of the lip2 gene fragment at the 5' end can greatly increase the expression level of recombinant LIP2 in the P. pastoris system. The distinct biochemical properties of our purified recombinant nfLIP2 and LIP2 suggested that they are potentially useful for various industrial applications.

A novel cold-active lipase from Candida albicans: cloning, expression and characterization of the recombinant enzyme

A novel lipase gene lip5 from the yeast Candida albicans was cloned and sequenced. Alignment of amino acid sequences revealed that 86-34% identity exists with lipases from other Candida species. The lipase and its mutants were expressed in the yeast Pichia pastoris, where alternative codon usage caused the mistranslation of 154-Ser and 293-Ser as leucine. 154-Ser to leucine resulted in loss of expression of Lip5, and 293-Ser to leucine caused a marked reduction in the lipase activity. Lip5-DM, which has double mutations that revert 154 and 293 to serine residues, showed good lipase activity, and was overexpressed and purified by (NH(4))(2)SO(4) precipitation and ion-exchange chromatography. The pure Lip5-DM was stable at low temperatures ranging from 15-35 °C and pH 5-9, with the optimal conditions being 15-25 °C and pH 5-6. The activation energy of recombinant lipase was 8.5 Kcal/mol between 5 and 25 °C, suggesting that Lip5-DM was a cold-active lipase. Its activity was found to increase in the presence of Zn(2+), but it was strongly inhibited by Fe(2+), Fe(3+), Hg(2+) and some surfactants. In addition, the Lip5-DM could not tolerate water-miscible organic solvents. Lip5-DM exhibited a preference for the short-and medium-chain length p-nitrophenyl (C4 and C8 acyl group) esters rather than the long chain length p-nitrophenyl esters (C12, C16 and C18 acyl group) with highest activity observed with the C8 derivatives. The recombinant enzyme displayed activity toward triacylglycerols, such as olive oil and safflower oil.

C-terminal region of Candida rugosa lipases affects enzyme activity and interfacial activation

Candida rugosa contains several lipase (CRLs) genes, and CRLs show diverse enzyme activity despite being highly homologous across their entire protein family. Previous studies found that LIP4 has a high esterase activity and a low lipolytic activity and lacks interfacial activation. To investigate whether the C-terminal region of the CRLs mediates enzymatic activity, chimeras were generated in which the C-terminus of LIP4 from either residue 374, 396, 417, or 444 to residue 534 was swapped with the corresponding peptide from the isoform LIP1. A chimeric lipase containing the C-terminus from 396 to 534 of LIP1 on a LIP4 scaffold showed activity similar to that of commercial CRL on triolein, and lipolytic activity increased 2-6-fold over that of LIP4. Moreover, interfacial activation was also observed in the chimeric lipase. To improve its enzymatic properties, a novel glycosylation site was added at residue 314. The new glycosylated lipase showed improved thermostability and enhancement in enzymatic activity, indicating its potential for use in further application.

Purification and characterization of the first recombinant bird pancreatic lipase expressed in Pichia pastoris: the turkey

BACKGROUND

The turkey pancreatic lipase (TPL) was purified from delipidated pancreases. Some biochemical properties and kinetic studies were determined using emulsified system and monomolecular film techniques. Those studies have shown that despite the accumulation of free fatty acids at the olive oil/water interface, TPL continues to hydrolyse efficiently the olive oil and the TC4 in the absence of colipase and bile salts, contrary to most classical digestive lipases which denaturate rapidly under the same conditions. The aim of the present study was to express TPL in the methylotrophic yeast Pichia pastoris in order to get a large amount of this enzyme exhibiting interesting biochemical properties, to purify and characterize the recombinant enzyme.

RESULTS

The recombinant TPL was secreted into the culture medium and the expression level reached about 15 mg/l after 4 days of culture. Using Q-PCR, the number of expression cassette integrated on Pichia genomic DNA was estimated to 5. The purified rTPL, with molecular mass of 50 kDa, has a specific activity of 5300 U/mg on emulsified olive oil and 9500 U/mg on tributyrin. The optimal temperature and pH of rTPL were 37°C and pH 8.5. The stability, reaction kinetics and effects of calcium ions and bile salts were also determined.

CONCLUSIONS

Our results show that the expressed TPL have the same properties as the native TPL previously purified. This result allows us the use of the recombinant enzyme to investigate the TPL structure-function relationships.

Site-specific saturation mutagenesis on residues 132 and 450 of Candida rugosa LIP2 enhances catalytic efficiency and alters substrate specificity in various chain lengths of triglycerides and esters

The catalytic versatility of recombinant Candida rugosa LIP2 has been known to have potential applications in industry. In this study, site-specific saturation mutagenesis on residues L132 and G450 of recombinant LIP2 has been employed to investigate the impact of both residues on substrate specificity of LIP2. Point mutations on L132 and G450 were done separately using mutagenic degenerate primer sets containing 32 codons to generate two libraries of mutants in Pichia pastoris . Replacements of amino acid on these mutants were identified as L132A, L132I, G450S, and G450A. In lipase activity assay, L132A and L132I mutants showed a shift of preference from short- to medium-chain triglyceride, whereas G450S and G450A mutants retained preferences as compared to wild-type LIP2. Among mutants, G450A has the highest activity on tributyrin. However, hydrolysis of p-nitrophenyl (p-NP) esters with L132A, L132I, and G450S did not show differences of preferences over medium- to long-chain esters except in G450A, which prefers only medium-chain ester as compared to wild-type LIP2. All mutants showed an enhanced catalytic activity and higher optimal temperature and pH stability as compared to wild-type LIP2.

Reactivity of Pure Candida rugosa Lipase Isoenzymes (Lip1, Lip2, and Lip3) in Aqueous and Organic Media. Influence of the Isoenzymatic Profile on the Lipase Performance in Organic Media

Three pure isoenzymes from Candida rugosa lipase (CRL: Lip1, Lip2, and Lip3) were compared in terms of their stability and reactivity in both aqueous and organic media. The combined effect of temperature and pH on their stability was studied applying a factorial design. The analysis of the response surfaces indicated that Lip1 and Lip3 have a similar stability, lower than that of Lip2. In aqueous media, Lip3 was the most active enzyme on the hydrolysis of p-nitrophenyl esters, whereas Lip1 showed the highest activity on the hydrolysis of most assayed triacylglycerides. The highest differences among isoenzymes were found in the hydrolysis of triacylglycerides. Thus, a short, medium, and long acyl chain triacylglyceride was the preferred substrate for Lip3, Lip1, and Lip2, respectively. In organic medium, Lip3 and Lip1 provided excellent results in terms of enantioselectivity in the resolution of ibuprofen (EF value over 0.90) and conversion, whereas initial esterification rate was higher for Lip3. However, the use of Lip2 resulted in lower values of conversion, enantiomeric excess, and enantioselectivity. In the case of trans-2-phenyl-1-cyclohexanol (TPCH) resolution, initial esterification rates were high except for Lip3, which also produced poor results in conversion and enantiomeric excess. The performance of the pure isoenzymes in the enantioselectivity esterification of these substrates was compared with different CRL crude preparations with known isoenzymatic content and the different results could not be explained by their isoenzymatic profile. Therefore, it can be concluded that other factors can also affect the catalysis of CRL and only the reproducibility between powders can ensure the reproducibility in synthesis reactions.

Understanding structural features of microbial lipases--an overview

The structural elucidations of microbial lipases have been of prime interest since the 1980s. Knowledge of structural features plays an important role in designing and engineering lipases for specific purposes. Significant structural data have been presented for few microbial lipases, while, there is still a structure-deficit, that is, most lipase structures are yet to be resolved. A search for 'lipase structure' in the RCSB Protein Data Bank (http://www.rcsb.org/pdb/) returns only 93 hits (as of September 2007) and, the NCBI database (http://www.ncbi.nlm.nih.gov) reports 89 lipase structures as compared to 14719 core nucleotide records. It is therefore worthwhile to consider investigations on the structural analysis of microbial lipases. This review is intended to provide a collection of resources on the instrumental, chemical and bioinformatics approaches for structure analyses. X-ray crystallography is a versatile tool for the structural biochemists and is been exploited till today. The chemical methods of recent interests include molecular modeling and combinatorial designs. Bioinformatics has surged striking interests in protein structural analysis with the advent of innumerable tools. Furthermore, a literature platform of the structural elucidations so far investigated has been presented with detailed descriptions as applicable to microbial lipases. A case study of Candida rugosa lipase (CRL) has also been discussed which highlights important structural features also common to most lipases. A general profile of lipase has been vividly described with an overview of lipase research reviewed in the past.

High-level expression of extracellular lipase Lip2 from Yarrowia lipolytica in Pichia pastoris and its purification and characterization

The extracellular lipase gene from Yarrowia lipolytica (YlLip2) was cloned into the pPICZalphaA and integrated into the genome of the methylotrophic yeast Pichia pastoris X-33. The lipase was successfully expressed and secreted with an apparent molecular weight of 39kDa using Saccharomyces cerevisiae secretion signal peptide (alpha-factor) under the control of the methanol inducible promoter of the alcohol oxidase 1 gene (AOX1). The lipase activity of 12,500,000U/l (2.10g total protein and 0.63g lipase per liter) was obtained in a fed-batch cultivation, where methanol feeding was linked to the dissolved oxygen content after initial glycerol culture. After fermentation, the supernatant was concentrated by ultrafiltration with a 10kDa cut off membrane and purified with ion exchange chromatography using Q Sepharose FF. Deglycosylation showed that the recombinant lipase is a glycoprotein which contains the same content of sugar (about 12%) as the native lipase from Y. lipolytica. The optimum temperature and pH of the recombinant lipase was 40 degrees C and 8.0, respectively. The lipase showed high activity toward long-chain fatty acid methyl esters (C12-C16).

Cloning and expression of a novel lipase gene from Pseudomonas fluorescens B52

A novel lipase gene (lipB52) was isolated directly from the genomic DNA of Pseudomonas fluorescens B52 with the genome-walking method, an effective method for isolating lipase gene from bacteria. There was an open reading frame (ORF) of 1854 bp, which encoded 617 amino acids. The lipase gene (lipB52) was cloned into expression vector pPIC9K and successfully integrated into a heterologous fungal host, Pichia pastoris KM71, and the recombinant Pichia pastoris were screened with a high throughput method. The recombinant was induced by methanol to secrete active lipase into the culture medium. The recombinant lipase LipB52 was also purified and characterized. The optimum temperature for the purified lipase LipB52 was 40 degrees C at pH 8.0. It exhibited better thermostability and pH stability than its homologs.

Cloning and expression of aMelanocarpus albomyces steryl esterase gene inPichia pastoris andTrichoderma reesei

The ste1 gene encoding a steryl esterase was isolated from the thermophilic fungus Melanocarpus albomyces. The gene has one intron, and it encodes a protein consisting of 576 amino acids. The deduced amino acid sequence of the steryl esterase was shown to be related to lipases and other esterases such as carboxylesterases. Formation of mature protein requires post-translational removal of a putative 18-amino-acid signal sequence and a 13-residue propeptide at the N-terminus. The intronless version of the Melanocarpus albomyces ste1 gene was expressed in Pichia pastoris under the inducible AOX1 promoter. The production level was low, and a large proportion of the total activity yield was found to be present intracellularly. However, the fact that steryl esterase activity was produced by P. pastoris cells carrying the expression cassette confirmed that the correct gene had been cloned. The ste1 gene was subsequently expressed in T. reesei under the inducible cbh1 promoter, and a clearly higher production level was obtained. About 60% of the total activity was bound to the fungal mycelium or to solid components of the culture medium, or existed as aggregates. Triton X-100 was successfully used to recover this activity. The heterologous production system in T. reesei provides a means of producing M. albomyces steryl esterase STE1 reliably in large scale for future studies.

Expression and purification of two lipases from Yarrowia lipolytica AS 2.1216

We isolated two lipase genes LIPY7, LIPY8 from Yarrowia lipolytica CGMCC (China general microbiological culture collection center) AS 2.1216. The LIPY7 and LIPY8 genes encode a 366 and a 371-amino acid protein, respectively. The lipase genes with 6 x His tag sequence were cloned into expression vector pPIC9K and successfully integrated into a heterologous fungal host Pichia pastoris KM71, respectively. The recombinants were induced by methanol to secrete active lipases into cultural medium. The recombinant lipases were also purified and characterized.

High yield expression of Lipase A from Candida antarctica in the methylotrophic yeast Pichia pastoris and its purification and characterisation

The current investigation focuses on shedding further light on the characteristics of lipase A from Candida antarctica (CalA), which has attracted growing attention in its suitability for industrial applications. CalA was functionally expressed in the methylotrophic yeast Pichia pastoris, purified and characterised. A classical fed-batch process and a semi-continuous process were developed and tested with regard to their yield capacity. Lipase concentrations of 0.88 and 0.55 g l(-1) were obtained using the fed-batch and semi-continuous processes, respectively. The semi-continuous process reaches a total activity of 10,233,000 U and so surpasses the fed-batch process reaching 7,530,000 U. The purified enzyme showed highest activity between 50 and 70 degrees C at pH 7.0 and a preference for short-chain triglycerides (C4-C8). Significantly reduced activity was observed in the presence of hydrophilic esters.

Understanding Candida rugosa lipases: an overview

Candida rugosa lipase (CRL) is one of the enzymes most frequently used in biotransformations. However, there are some irreproducibility problems inherent to this biocatalyst, attributed either to differences in lipase loading and isoenzymatic profile or to other medium-engineering effects (temperature, a(w), choice of solvent, etc.). In addition, some other properties (influence of substrate and reaction conditions on the lid movement, differences in the glycosylation degree, post-translational modifications) should not be ruled out. In the present paper the recent developments published in the CRL field are overviewed, focusing on: (a) comparison of structural and biochemical data among isoenzymes (Lip1-Lip5), and their influence in the biocatalytical performance; (b) developments in fermentation technology to achieve new crude C. rugosa lipases; (c) biocatalytical reactivity of each isoenzyme, and methods for characterising them in crude CRL; (d) state-of-the-art of new applications performed with recombinant CRLs, both in CRL-second generation (wild-type recombinant enzymes), as well as in CRL-third generation, (mutants of the wt-CRL).

Multiple mutagenesis of the Candida rugosa LIP1 gene and optimum production of recombinant LIP1 expressed in Pichia pastoris

Candida rugosa lipase, a significant catalyst, had been widely employed to catalyze various chemical reactions such as non-specific, stereo-specific hydrolysis and esterification for industrial biocatalytic applications. Several isozymes encoded by the lip gene family, namely lip1 to lip7, possess distinct thermal stability and substrate specificity, among which the recombinant LIP1 showed a distinguished catalytic characterization. In this study, we utilized PCR to remove an unnecessary linker of pGAPZalphaC vector and used overlap extension PCR-based multiple site-directed mutagenesis to convert the 19 non-universal CTG-serine codons into universal TCT-serine codons and successfully express a highly active recombinant C. rugosa LIP1 in the Pichia expression system. Response surface methodology and 4-factor-5-level central composite rotatable design were adopted to evaluate the effects of growth parameters, such as temperature (21.6-38.4 degrees C), glucose concentration (0.3-3.7%), yeast extract (0.16-1.84%), and pH (5.3-8.7) on the lipolytic activity of LIP1 and biomass of P. pastoris. Based on ridge max analysis, the optimum LIP1 production conditions were temperature, 24.1 degrees C; glucose concentration, 2.6%; yeast extract, 1.4%; and pH 7.6. The predicted value of lipolytic activity was 246.9+/-39.7 U/ml, and the actual value was 253.3+/-18.8 U/ml. The lipolytic activity of the recombinant LIP1 resulting from the present work is twofold higher than that achieved by a methanol induction system.

Protein engineering and applications of Candida rugosa lipase isoforms

Commercial preparations of Candida rugosa lipase (CRL) are mixtures of lipase isoforms used for the hydrolysis and synthesis of various esters. The presence of variable isoforms and the amount of lipolytic protein in the crude lipase preparations lead to a lack of reproducibility of biocatalytic reactions. Purification of crude CRL improve their substrate specificity, enantioselectivity, stability, and specific activities. The expression of the isoforms is governed by culture or fermentation conditions. Unfortunately, the nonsporogenic yeast C. rugosa does not utilize the universal codon CTG for leucine; therefore, most of the CTG codons were converted to universal serine triplets by site-directed mutagenesis to gain expression of functional lipase in heterologous hosts. Recombinant expressions by multiple-site mutagenesis or complete synthesis of the lipase gene are other possible ways of obtaining pure and different CRL isoforms, in addition to culture engineering. Protein engineering of purified CRL isoforms allows the tailoring of enzyme function. This involves computer modeling based on available 3-D structures of lipase isoforms. Lid swapping and DNA shuffling techniques can be used to improve the enantioselectivity, thermostability, and substrate specificity of CRL isoforms and increase their biotechnological applications. Lid swapping can result in chimera proteins with new functions. The sequence of the lid can affect the activity and specificity of recombinant CRL isoforms. Candida rugosa lipase is toxicologically safe for food applications. Protein engineering through lid swapping and rationally designed site-directed mutagenesis will continue to lead to the production of CRL isoforms with improved catalytic power, thermostability, enantioselectivity, and substrate specificity, while providing evidence for the mechanisms of actions of the various isoforms.