The short form of the recombinant CAL-A-type lipase UM03410 from the smut fungus Ustilago maydis exhibits an inherent trans-fatty acid selectivity

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.

Further Characterization of Lipase B from Ustilago maydis Expressed in Pichia pastoris: a Member of the Candida antarctica Lipase B-like Superfamily

Lipases from the basidiomycete fungus Ustilago maydis are promising but underexplored biocatalysts due to their high homology with Candida antarctica lipases. This study provides a comprehensive characterization of a recombinant CALB-like lipase from U. maydis, expressed in Pichia pastoris (rUMLB), and compares its properties with those of the well-studied recombinant lipase B from C. antarctica (rCALB). Biochemical analyses included evaluations of optimal pH, temperature, triglyceride (TG) preference for short- and medium-chain acyl groups, phospholipase and amidase activities, enantiopreference, thermostability, stability in organic solvents, and response to NaCl concentrations. rUMLB, a glycosylated enzyme with a molecular weight of 38.6 kDa, exhibited cold-active behavior at 0 °C and preferred hydrolysis of partially soluble short-chain fatty acid TGs, like rCALB. In addition, rUMLB was also capable of hydrolyzing insoluble long-chain triglycerides like rCALB. The half-life at 50 °C for rCALB was approximately 1.6 times greater than that of UMLB, which has fewer surface-exposed proline residues. Both enzymes displayed strong (R)-enantiopreference on (R)-glycidyl butyrate, (R)-ethyl hydroxy butyrate, and (R)-methyl hydroxy valerate enantiomers with increased activity in non-polar solvents. However, rUMLB was more sensitive to polar solvents. Notably, rUMLB was activated at high NaCl concentrations, as previously reported for rCALB. rUMLB showed amidase activity on capsaicinoids similar to rCALB; however, rUMLB uniquely demonstrated significant phospholipase activity toward natural phospholipids, a feature not observed in rCALB. The analysis of the cavity adjacent to the active site in the UMLB model and CALB structure revealed slightly larger area, volume, and hydrophobicity values for UMLB. These comparative insights highlight the functional diversity within the CALB-type lipase family, underscoring the potential of UMLB as a versatile biocatalyst and providing valuable information for biotechnological applications and for understanding enzyme structure-function relationships within the CALB superfamily.

An sn-2 regioselective lipase with cis-fatty acid preference from Cordyceps militaris: Biochemical characterization and insights into its regioselective mechanism

Lipase with unique regioselectivity is an attractive biocatalyst for elaborate lipid modification. However, the excavation of novel sn-2 regioselective lipases is difficult due to their scarcity in nature, with Candida antarctica lipase A (CALA) being the pronouncedly reported one. Here, we identified a novel CALA-like lipase from Cordyceps militaris (CACML7) via in silico mining. Through chiral-phase high-performance liquid chromatography, we determined that CACML7 displays sn-2 regioselectivity (>68 %) as does CALA, but exhibits distinctive chain length selectivity and bias against unsaturated fats. Notably, the curvature of the acyl-binding tunnel was expected to contribute to the 2.2-fold higher preference for cis-fatty acid (C18:1, cis-Δ9) over trans-fatty acid (C18:1, trans-Δ9) unlike trans-active CALA. Random pose docking of trioleoylglycerol (TOG) into the active site of a lid-truncated mutant of CACML7 revealed that TOG accepts a tuning fork conformation, of which the precise positioning of the reactive ester group towards the catalytic center was only favorable via sn-2 binding mode. The unique active site morphology, which we refer to as an "acyl-binding tunnel with a narrow entrance," may contribute to the sn-2 regioselectivity of CACML7. Our data provide an attractive model to better understand the mechanism underlying sn-2 regioselectivity.

Huitlacoche (Ustilago maydis), an Iconic Mexican Fungal Resource: Biocultural Importance, Nutritional Content, Bioactive Compounds, and Potential Biotechnological Applications

Worldwide, the fungus known as huitlacoche (Ustilago maydis (DC.) Corda) is a phytopathogen of maize plants that causes important economic losses in different countries. Conversely, it is an iconic edible fungus of Mexican culture and cuisine, and it has high commercial value in the domestic market, though recently there has been a growing interest in the international market. Huitlacoche is an excellent source of nutritional compounds such as protein, dietary fiber, fatty acids, minerals, and vitamins. It is also an important source of bioactive compounds with health-enhancing properties. Furthermore, scientific evidence shows that extracts or compounds isolated from huitlacoche have antioxidant, antimicrobial, anti-inflammatory, antimutagenic, antiplatelet, and dopaminergic properties. Additionally, the technological uses of huitlacoche include stabilizing and capping agents for inorganic nanoparticle synthesis, removing heavy metals from aqueous media, having biocontrol properties for wine production, and containing biosurfactant compounds and enzymes with potential industrial applications. Furthermore, huitlacoche has been used as a functional ingredient to develop foods with potential health-promoting benefits. The present review focuses on the biocultural importance, nutritional content, and phytochemical profile of huitlacoche and its related biological properties as a strategy to contribute to global food security through food diversification; moreover, the biotechnological uses of huitlacoche are also discussed with the aim of contributing to the use, propagation, and conservation of this valuable but overlooked fungal resource.

Photoenzymatic decarboxylation: A promising way to produce sustainable aviation fuels and fine chemicals

As one of the fastest-growing carbon emission sources, the aviation sector is severely restricted by carbon emission reduction targets. Sustainable aviation fuel (SAF) has emerged as the most potential alternative to traditional aviation fuel, but harsh production technologies limit its commercialization. Fatty acids photodecarboxylase from Chlorella variabilis NC64A (CvFAP), the latest discovered photoenzyme, provides promising approaches to produce various carbon-neutral biofuels and fine chemicals. This review highlights the state-of-the-art strategies to enhance the application of CvFAP in carbon-neutral biofuel and fine chemicals production, including supplementing alkane as decoy molecular, screening efficient CvFAP variants with directed evolution, constructing genetic strains, employing biphasic catalytic system, and immobilizing CvFAP in an efficient photobioreactor. Furthermore, future opportunities are suggested to enhance photoenzymatic decarboxylation and explore the catalytic mechanism of CvFAP. This review provides a broad context to improve CvFAP catalysis and advance its potential applications.

Engineering Fatty Acid Photodecarboxylase to Enable Highly Selective Decarboxylation of trans Fatty Acids

Due to the high risk of heart disease caused by the intake of trans fatty acids, a method to eliminate trans fatty acids from foods has become a critical issue. Herein, we engineered fatty acid photo-decarboxylase from Chlorella variabilis (CvFAP) to selectively catalyze the decarboxylation of trans fatty acids to yield readily-removed hydrocarbons and carbon dioxide, while cis fatty acids remained unchanged. An efficient protein engineering based on FRISM strategy was implemented to intensify the electronic interaction between the residues and the double bond of the substrate that stabilized the binding of elaidic acid in the channel. For the model compounds, oleic acid and elaidic acid, the best mutant, V453E, showed a one-thousand-fold improvement in the trans-over-cis (ToC) selectivity compared with wild type (WT). As the first report of the direct biocatalytic decarboxylation resolution of trans/cis fatty acids, this work offers a safe, facile, and eco-friendly process to eliminate trans fatty acids from edible oils.

Monitoring of the enzymatic activity of intracellular lipases of

Under nitrogen starvation, Ustilago maydis forms lipid droplets (LDs). Although the dynamics of these organelles are known in the literature, the identity of the lipases implicated in their degradation is unknown. We determined lipase activity and identified the intracellular lipases expressed during growth under nitrogen starvation and YPD media by zymograms. The results showed that cytosolic extracts exhibited higher lipase activity when cells were grown in YPD. Under nitrogen starvation, lipase activity was not detected after 24 h of culture, resulting in lipid accumulation in LDs. This suggests that these lipases could be implicated in LD degradation. In the zymogram, two bands, one of 25 and the other of 37 kDa, presented lipase activity. The YPD extracts showed lipase activity in olive and almond oils, which contain triacylglycerols with mono and polyunsaturated fatty acids. This is the first report about U. maydis cytosolic lipases involved in LD degradation.

Alteration of Chain Length Selectivity of Candida antarctica Lipase A by Semi-Rational Design for the Enrichment of Erucic and Gondoic Fatty Acids

Biotechnological strategies using renewable materials as starting substrates are a promising alternative to traditional oleochemical processes for the isolation of different fatty acids. Among them, long chain mono-unsaturated fatty acids are especially interesting in industrial lipid modification, since they are precursors of several economically relevant products, including detergents, plastics and lubricants. Therefore, the aim of this study was to develop an enzymatic method in order to increase the percentage of long chain mono-unsaturated fatty acids from Camelina and Crambe oil ethyl ester derivatives, by using selective lipases. Specifically, the focus was on the enrichment of gondoic (C20:1 cisΔ11) and erucic acid (C22:1 cisΔ13) from Camelina and Crambe oil derivatives, respectively. The pursuit of this goal entailed several steps, including: (i) the choice of a suitable lipase scaffold to serve as a protein engineering template (Candida antarctica lipase A); (ii) the identification of potential amino acid targets to disrupt the binding tunnel at the adequate location; (iii) the design, creation and high-throughput screening of lipase mutant libraries; (iv) the study of the selectivity towards different chain length p-nitrophenyl fatty acid esters of the best hits found, as well as the analysis of the contribution of each amino acid change and the outcome of combining several of the aforementioned residue alterations and, finally, (v) the selection and application of the most promising candidates for the fatty acid enrichment biocatalysis. As a result, enrichment of C22:1 from Crambe ethyl esters was achieved either, in the free fatty acid fraction (wt, 78%) or in the esterified fraction (variants V1, 77%; V9, 78% and V19, 74%). Concerning the enrichment of C20:1 when Camelina oil ethyl esters were used as substrate, the best variant was the single mutant V290W, which doubled its content in the esterified fraction from approximately 15% to 34%. A moderately lower increase was achieved by V9 and its two derived triple mutant variants V19 and V20 (27%).

Biodegradable Core⁻Multishell Nanocarriers: Influence of Inner Shell Structure on the Encapsulation Behavior of Dexamethasone and Tacrolimus

We here present the synthesis and characterization of a set of biodegradable core⁻multishell (CMS) nanocarriers. The CMS nanocarrier structure consists of hyperbranched polyglycerol (hPG) as core material, a hydrophobic (12, 15, 18, 19, and 36 C-atoms) inner and a polyethylene glycol monomethyl ether (mPEG) outer shell that were conjugated by ester bonds only to reduce the toxicity of metabolites. The loading capacities (LC) of the drugs, dexamethasone and tacrolimus, and the aggregate formation, phase transitions, and degradation kinetics were determined. The intermediate inner shell length (C15) system had the best overall performance with good LCs for both drugs as well as a promising degradation and release kinetics, which are of interest for dermal delivery.

The 3D model of the lipase/acyltransferase from Candida parapsilosis, a tool for the elucidation of structural determinants in CAL-A lipase superfamily

Because lipids are hydrophobic, the development of efficient bioconversions in aqueous media free of organic solvents is particularly challenging for green oleochemistry. Within this aim, enzymes exhibiting various abilities to catalyze acyltransfer reaction in water/lipid systems have been identified. Among these, CpLIP2 from Candida parapsilosis has been characterized as a lipase/acyltransferase, able to catalyze acyltransfer reactions preferentially to hydrolysis in the presence of particularly low acyl acceptor concentration and high thermodynamic activity of water (aw>0.9). Lipase/acyltransferases are thus of great interest, being able to produce new esters at concentrations above the thermodynamic equilibrium of hydrolysis/esterification with limited to no release of free fatty acids. Here, we present a 3D model of CpLIP2 based on homologies with crystallographic structures of Pseudozyma antarctica lipase A. Indeed, the two enzymes have 31% of identity in their primary sequence, yielding a same general structure, but different catalytic properties. The quality of the calculated CpLIP2 model was confirmed by several methods. Limited proteolysis confirmed the location of some loops at the surface of the protein 3D model. Directed mutagenesis also supported the structural model constructed on CAL-A template: the functional properties of various mutants were consistent with their structure-based putative involvement in the oxyanion hole, substrate specificity, acyltransfer or hydrolysis catalysis and structural stability. The CpLIP2 3D model, in comparison with CAL-A 3D structure, brings insights for the elucidation and improvement of the structural determinants involved in the exceptional acyltransferase properties of this promising biocatalyst and of homologous enzymes of the same family.

A novel calb-type lipase discovered by fungal genomes mining

The fungus Pseudozyma antarctica produces a lipase (CalB) with broad substrate specificity, stability, high regio- and enantio-selectivity. It is active in non-aqueous organic solvents and at elevated temperatures. Hence, CalB is a robust biocatalyst for chemical conversions on an industrial scale. Here we report the in silico mining of public metagenomes and fungal genomes to discover novel lipases with high homology to CalB. The candidates were selected taking into account homology and conserved motifs criteria, as well as, phylogeny and 3D model analyses. The most promising candidate (PlicB) presented interesting structural properties. PlicB was expressed in a heterologous host, purified and partially characterized. Further experiments will allow finding novel catalytic properties with biotechnological interest.

Homologous yeast lipases/acyltransferases exhibit remarkable cold-active properties

Lipases/acyltransferases catalyse acyltransfer to various nucleophiles preferentially to hydrolysis even in aqueous media with high thermodynamic activity of water (a w >0.9). Characterization of hydrolysis and acyltransfer activities in a large range of temperature (5 to 80 °C) of secreted recombinant homologous lipases of the Pseudozyma antarctica lipase A superfamily (CaLA) expressed in Pichia pastoris, enlighten the exceptional cold-activity of two remarkable lipases/acyltransferases: CpLIP2 from Candida parapsilosis and CtroL4 from Candida tropicalis. The activation energy of the reactions catalysed by CpLIP2 and CtroL4 was 18-23 kJ mol(-1) for hydrolysis and less than 15 kJ mol(-1) for transesterification between 5 and 35 °C, while it was respectively 43 and 47 kJ mol(-1) with the thermostable CaLA. A remarkable consequence is the high rate of the reactions catalysed by CpLIP2 and CtroL4 at very low temperatures, with CpLIP2 displaying at 5 °C 65 % of its alcoholysis activity and 45 % of its hydrolysis activity at 30 °C. These results suggest that, within the CaLA superfamily and its homologous subgroups, common structural determinants might allow both acyltransfer and cold-active properties. Such biocatalysts are of great interest for the efficient synthesis or functionalization of temperature-sensitive lipid derivatives, or more generally to lessen the environmental impact of biocatalytic processes.