The N-terminal His-tag and the recombination process affect the biochemical properties of Staphylococcus aureus lipase produced in Escherichia coli

Expression and characterization of an organic solvent tolerant recombinant lipase from Staphylococcus capitis SH6 for food wastewater treatment

The study illustrated here aims on an organic solvent tolerant lipase from Staphylococcus capitis (SCL). The gene part, encoding the mature lipase, was cloned and sequenced. The concluded polypeptide sequence, equivalent to the protein, consist of 388 amino acid residues with a molecular mass of about 45 kDa. A structure-based alignment of the SCL amino acid sequence shows high identities with those many staphylococcal lipases. From this alignment of sequences, the catalytic triad (Ser 117, Asp 308 and His 347) of SCL could be identified. The mature part of the SCL was expressed in Escherichia coli and the recombinant lipase (r-SCL) was purified to homogeneity. The purified r-SCL presented a quite interesting stability at low temperatures (< 30 °C) and the enzyme was found to be highly stable in polar organic solvent and at a pH ranging from 3 to 12. After that, we have demonstrated that the recombinant enzyme may be implicated in the biodegradability of oily wastewater from effluents of fast-food restaurants; the maximum conversion yield into fatty acids obtained at 30 °C, was 65%.

Comparative study of His- and Non-His-tagged CLIC proteins, reveals changes in their enzymatic activity

The chloride intracellular ion channel protein (CLIC) family are a unique set of ion channels that can exist as soluble and integral membrane proteins. New evidence has emerged that demonstrates CLICs' possess oxidoreductase enzymatic activity and may function as either membrane-spanning ion channels or as globular enzymes. To further characterize the enzymatic profile of members of the CLIC family and to expand our understanding of their functions, we expressed and purified recombinant CLIC1, CLIC3, and a non-functional CLIC1-Cys24A mutant using a Histidine tag, bacterial protein expression system. We demonstrate that the presence of the six-polyhistidine tag at the amino terminus of the proteins led to a decrease in their oxidoreductase enzymatic activity compared to their non-His-tagged counterparts, when assessed using 2-hydroxyethyl disulfide as a substrate. These results strongly suggest the six-polyhistidine tag alters CLIC's structure at the N-terminus, which also contains the enzyme active site. It also raises the need for caution in use of His-tagged proteins when assessing oxidoreductase protein enzymatic function.

Identification and Heterologous Production of a Lipase from Geobacillus kaustophilus DSM 7263T and Tailoring Its N-Terminal by a His-Tag Epitope

Lipases are versatile biocatalysts with many biotechnological applications and the necessity of screening, production and characterization of new lipases from diverse microbial strains to meet industrial needs is constantly emerging. In this study, the lipase gene (gklip) from a thermophilic bacterium, Geobacillus kaustophilus DSM 7263 ^T was cloned into the pET28a ( +) vector with N-terminal 6xHis-tag. The recombinant gklip gene was heterologously expressed in host E. coli BL21 (DE3) cells and purified by Ni-NTA affinity chromatography. Histidine tag was removed from the purified 6xHistag-Gklip enzyme with thrombin enzyme and the molecular mass was determined to be approximately 43 kDa by SDS-PAGE. Gklip showed optimal activity at pH 8.0 and 50 °C. The specific hydrolytic activities against substrates were significantly increased by the removal of the His-tag. K_m and k_cat values of Gklip against p-nitrophenyl palmitate (pNPP, 4-nitrophenyl palmitate) as the target substrate were found to be as 1.22 mM and 417.1 min^-1, respectively. Removing His-tag changed the substrate preference of the enzyme leading to maximum lipolytic activity towards C10 and C12 lipids. Similarly, the activity against coconut oil that containing 62% medium-chain fatty acids was significantly higher than other oils. Furthermore, preservation of activity in the presence of inhibitors, organic solvents support the effect of lid structure of the enzyme.

Effect of the His-Tag Location on Decapping Scavenger Enzymes and Their Hydrolytic Activity toward Cap Analogs

Decapping scavenger enzymes (DcpSs) are important players in mRNA degradation machinery and conserved in eukaryotes. Importantly, human DcpS is the recognized target for spinal muscular atrophy (SMA) and acute myeloid leukemia (AML) therapy, and has recently been connected to development of intellectual disability. Most recombinant DcpSs used in biochemical and biophysical studies are prepared as tagged proteins, with polyhistidine (His-tag) at the N-terminus or C-terminus. Our work is the first report on the parallel characterization of three versions of DcpSs (native and N- or C-terminally tagged) of three species (humans, Caenorhabditis elegans , and Ascaris suum). The native forms of all three enzymes were prepared by N-(His)₁₀ tag cleavage. Protein thermal stability, measured by differential scanning fluorimetry (DSF), was unaffected in the case of native and tagged versions of human and A. suum DcpS; however, the melting temperature (T _m) of C. elagans DcpS of was significantly influenced by the presence of the additional N- or C-tag. To investigate the impact of the tag positioning on the catalytic properties of DcpS, we tested the hydrolytic activity of native DcpS and their His-tagged counterparts toward cap dinucleotides (m⁷GpppG and m₃ ^2,2,7GpppG) and m⁷GDP. The kinetic data indicate that dinucleotide substrates are hydrolyzed with comparable efficiency by native human and A. suum DcpS and their His-tagged forms. In contrast, both His-tagged C. elegans DcpSs exhibited higher activity toward m⁷GpppG than the native enzyme. m⁷GDP is resistant to enzymatic cleavage by all three forms of human and nematode DcpS.

Refolding with Simultaneous Purification of Recombinant Serratia marcescens Lipase by One-Step Ultrasonication Process

A new lipase from Serratia marcescens SRICI-01 (Trx-SmL) was successfully overexpressed in Escherichia coli with thioredoxin (Trx) fusion tag. Intriguingly, the concentration of potassium phosphate buffer (KPB) showed significant impact on the aggregation state of Trx-SmL during ultrasonic disruption. The proportion of inclusion bodies increased dramatically with the increase of KPB concentration from almost completely soluble in 10 mM KPB to insoluble in 200 mM KPB. Based on this new finding, a novel method for refolding and purification of recombinant Trx-SmL was developed by one-step ultrasonication. The Trx-SmL was firstly precipitated in 200 mM KPB, washed for three times, and subsequently subjected to ultrasonic process in 10 mM KPB where refolding and purification occurred simultaneously. This established method was proved to be a straightforward, economical, and efficient purification approach to facilely obtain recombinant Trx-SmL protein with high purity (> 90%) and activity recovery yield (> 80%) from cell lysates. The application potential of the purified fusion Trx-SmL was further demonstrated by kinetic bioresolution of (±)-trans-3-(4-methoxyphenyl)glycidic acid methyl ester [(±)-MPGM] producing optically pure (-)-MPGM, a key intermediate for diltiazem, with an overall yield of 41.5% and ee of 99%.

Effects of His-tag on Catalytic Activity and Enantioselectivity of Recombinant Transaminases

Recombinant proteins were often expressed with His-tag to simplify the purification process. Among them, transaminase was mostly expressed with fusion tags and widely used in the production of numerous amino moieties. However, the existence of the His-tag has been reported to affect various properties of different recombinant enzymes, while the effect on transaminase was rarely studied. In this paper, we investigated the effect of His-tag on transaminase based on the various activities of 4-aminobutyrate-2-oxoglutarate transaminase (GabT) when it was expressed in vector pETDuet-1. We found that His-tag did not affect the enantioselectivity, but decreased the catalytic activity to different extents according to its existence and location. Native GabT maintained the highest catalytic activity; GabT with C-terminal His-tag showed slightly lower activity than native GabT but about 2.2-fold higher than GabT with N-terminal His-tag. Besides, other fusion tags like T7-tag and S-tag inserted between N-His-tag and GabT can relieve the decreasing effect of His-tag on GabT activity. Furthermore, whole cell catalytic activity of several transaminases was improved by deleting the N-terminal His-tag. This study provided a strategy for the efficient expression of recombinant transaminase with improved catalytic activity and might attract attention to the effect of His-tag on other enzymatic properties.

Tailoring recombinant lipases: keeping the His-tag favors esterification reactions, removing it favors hydrolysis reactions

We determined the effect of the His-tag on the structure, activity, stability and immobilization of LipC12, a highly active lipase from a metagenomic library. We purified LipC12 with a N-terminal His-tag and then removed the tag using tobacco etch virus (TEV) protease. Circular dichroism analysis showed that the overall structure of LipC12 was largely unaffected by His-tag removal. The specific hydrolytic activities against natural and artificial substrates were significantly increased by the removal of the His-tag. On the other hand, His-tagged LipC12 was significantly more active and stable in the presence of polar organic solvents than untagged LipC12. The immobilization efficiency on Immobead 150 was 100% for both forms of LipC12 and protein desorption studies confirmed that the His-tag does not participate in the covalent binding of the enzyme. In the case of immobilized LipC12, the His-tag negatively influenced the hydrolytic activity, as it had for the free lipase, however, it positively influenced the esterification activity. These results raise the possibility of tailoring recombinant lipases for different applications, where the His-tag may be retained or removed, as appropriate for the desired activity.

Ribo-attenuators: novel elements for reliable and modular riboswitch engineering

Riboswitches are structural genetic regulatory elements that directly couple the sensing of small molecules to gene expression. They have considerable potential for applications throughout synthetic biology and bio-manufacturing as they are able to sense a wide range of small molecules and regulate gene expression in response. Despite over a decade of research they have yet to reach this considerable potential as they cannot yet be treated as modular components. This is due to several limitations including sensitivity to changes in genetic context, low tunability, and variability in performance. To overcome the associated difficulties with riboswitches, we have designed and introduced a novel genetic element called a ribo-attenuator in Bacteria. This genetic element allows for predictable tuning, insulation from contextual changes, and a reduction in expression variation. Ribo-attenuators allow riboswitches to be treated as truly modular and tunable components, thus increasing their reliability for a wide range of applications.

Immobilization of Ulp1 protease on NHS-activated Sepharose: a useful tool for cleavage of the SUMO tag of recombinant proteins

OBJECTIVE

To fabricate an active and stable enzyme through covalent immobilization, a Ubl-specific protease (Ulp1) was used to cleave small ubiquitin-like modifier (SUMO) fusion proteins.

RESULTS

We immobilized Ulp1 on N-hydroxysuccinimide (NHS)-activated Sepharose with a coupling efficiency of 1.7 mg/ml. The immobilized Ulp1 maintains 95% substrate-cleavage ability and significantly enhances pH and thermal stability, especially can withstand pH of 10.5. Besides resistance against some small molecules, the immobilized Ulp1 can tolerate 15% (v/v) DMSO and 20% (v/v) ethanol. It can be reused for more than 15 batch reactions with 90% activity retention. This provides a fast purification system to quickly obtain cleaved recombinant proteins with 95% purity from cell lysates with the application of immobilized Ulp1.

CONCLUSIONS

Ulp1 used in immobilization form is a potentially useful tool for cleavage of SUMO-tagged proteins and may reduce time and cost of protein purification.

Study of Class I and Class III Polyhydroxyalkanoate (PHA) Synthases with Substrates Containing a Modified Side Chain

Polyhydroxyalkanoates (PHAs) are carbon and energy storage polymers produced by a variety of microbial organisms under nutrient-limited conditions. They have been considered as an environmentally friendly alternative to oil-based plastics due to their renewability, versatility, and biodegradability. PHA synthase (PhaC) plays a central role in PHA biosynthesis, in which its activity and substrate specificity are major factors in determining the productivity and properties of the produced polymers. However, the effects of modifying the substrate side chain are not well understood because of the difficulty to accessing the desired analogues. In this report, a series of 3-(R)-hydroxyacyl coenzyme A (HACoA) analogues were synthesized and tested with class I synthases from Chromobacterium sp. USM2 (PhaCCs and A479S-PhaCCs) and Caulobacter crescentus (PhaCCc) as well as class III synthase from Allochromatium vinosum (PhaECAv). It was found that, while different PHA synthases displayed distinct preference with regard to the length of the alkyl side chains, they could withstand moderate side chain modifications such as terminal unsaturated bonds and the azide group. Specifically, the specific activity of PhaCCs toward propynyl analogue (HHxyCoA) was only 5-fold less than that toward the classical substrate HBCoA. The catalytic efficiency (kcat/Km) of PhaECAv toward azide analogue (HABCoA) was determined to be 2.86 × 10(5) M(-1) s(-1), which was 6.2% of the value of HBCoA (4.62 × 10(6) M(-1) s(-1)) measured in the presence of bovine serum albumin (BSA). These side chain modifications may be employed to introduce new material functions to PHAs as well as to study PHA biogenesis via click-chemistry, in which the latter remains unknown and is important for metabolic engineering to produce PHAs economically.

A Chimeric Affinity Tag for Efficient Expression and Chromatographic Purification of Heterologous Proteins from Plants

The use of plants as expression hosts for recombinant proteins is an increasingly attractive option for the production of complex and challenging biopharmaceuticals. Tools are needed at present to marry recent developments in high-yielding gene vectors for heterologous expression with routine protein purification techniques. In this study, we designed the Cysta-tag, a new purification tag for immobilized metal affinity chromatography (IMAC) of plant-made proteins based on the protein-stabilizing fusion partner SlCYS8. We show that the Cysta-tag may be used to readily purify proteins under native conditions, and then be removed enzymatically to isolate the protein of interest. We also show that commonly used protease recognition sites for linking purification tags are differentially stable in leaves of the commonly used expression host Nicotiana benthamiana, with those linkers susceptible to cysteine proteases being less stable then serine protease-cleavable linkers. As an example, we describe a Cysta-tag experimental scheme for the one-step purification of a clinically useful protein, human α1-antitrypsin, transiently expressed in N. benthamiana. With potential applicability to the variety of chromatography formats commercially available for IMAC-based protein purification, the Cysta-tag provides a convenient means for the efficient and cost-effective purification of recombinant proteins from plant tissues.

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.

Over-expression of recombinant proteins with N-terminal His-tag via subcellular uneven distribution in Escherichia coli

Specific tags with defined amino acid residues are widely used to purify or probe target proteins. Interestingly, the tagging system occasionally results in an increase of the recombinant protein expression in vivo. Here, we systematically examined this phenomenon using a poly-histidine (His)-tag fused to N- or C-terminal region of green, red, and blue fluorescent proteins by quantification and uneven distribution in cytoplasm of Escherichia coli. This effect was further supported by the distinct over-expression of several unrelated proteins, such as esterase, neopullulanase, and chloramphenicol acetyltransferase, tagging with the same tag. These results suggest that a poly-His-tag placed at N-terminal region can induce over-expression of recombinant protein via subcellular uneven distribution in vivo.

Enhancing the thermostability of a cold-active lipase from Penicillium cyclopium by in silico design of a disulfide bridge

Cysteine mutants of a cold-active lipase (PcLipI) from Penicillium cyclopium were designed by the software Disulfide by Design Ver. 1.20 in an effort to improve enzyme thermostability by addition of a disulfide bridge. Those mutants predicted by molecular dynamics simulation to have better thermostability than the wild type were first expressed in Escherichia coli BL21(DE3) and then, for further investigation, in Pichia pastoris GS115. By replacing Val248 and Thr251 with cysteines to create a disulfide bridge, the recombinant lipases reE-PcLipV248C-T251C (expressed in E. coli) and reP-PcLipV248C-T251C (expressed in P. pastoris) were obtained. Both had enhanced thermostability with half-lives at 35 °C about 4.5- and 12.8-fold longer than that of the parent PcLipI expressed in E. coli and P. pastoris, respectively. The temperature optima of reE-PcLipV248C-T251C and reP-PcLipV248C-T251C were 35 and 30 °C, which were each 5 °C higher than those of the parent PcLipI expressed in E. coli and P. pastoris. The K ms of reE-PcLipV248C-T251C and reP-PcLipV248C-T251C toward tributyrin were 53.2 and 39.5 mM, while their V maxs were 1,460 and 3,800 U/mg, respectively. PcLipV248C-T251C had better thermostability and catalytic efficiency than the other mutants and the parent PcLipI.

Research applications of proteolytic enzymes in molecular biology

Proteolytic enzymes (also termed peptidases, proteases and proteinases) are capable of hydrolyzing peptide bonds in proteins. They can be found in all living organisms, from viruses to animals and humans. Proteolytic enzymes have great medical and pharmaceutical importance due to their key role in biological processes and in the life-cycle of many pathogens. Proteases are extensively applied enzymes in several sectors of industry and biotechnology, furthermore, numerous research applications require their use, including production of Klenow fragments, peptide synthesis, digestion of unwanted proteins during nucleic acid purification, cell culturing and tissue dissociation, preparation of recombinant antibody fragments for research, diagnostics and therapy, exploration of the structure-function relationships by structural studies, removal of affinity tags from fusion proteins in recombinant protein techniques, peptide sequencing and proteolytic digestion of proteins in proteomics. The aim of this paper is to review the molecular biological aspects of proteolytic enzymes and summarize their applications in the life sciences.

A simple and effective strategy for solving the problem of inclusion bodies in recombinant protein technology: His-tag deletions enhance soluble expression

The formation of inclusion bodies (IBs) in recombinant protein biotechnology has become one of the most frequent undesirable occurrences in both research and industrial applications. So far, the pET System is the most powerful system developed for the production of recombinant proteins when Escherichia coli is used as the microbial cell factory. Also, using fusion tags to facilitate detection and purification of the target protein is a commonly used tactic. However, there is still a large fraction of proteins that cannot be produced in E. coli in a soluble (and hence functional) form. Intensive research efforts have tried to address this issue, and numerous parameters have been modulated to avoid the formation of inclusion bodies. However, hardly anyone has noticed that adding fusion tags to the recombinant protein to facilitate purification is a key factor that affects the formation of inclusion bodies. To test this idea, the industrial biocatalysts uridine phosphorylase from Aeropyrum pernix K1 and (+)-γ-lactamase and (-)-γ-lactamase from Bradyrhizobium japonicum USDA 6 were expressed in E. coli by using the pET System and then examined. We found that using a histidine tag as a fusion partner for protein expression did affect the formation of inclusion bodies in these examples, suggesting that removing the fusion tag can promote the solubility of heterologous proteins. The production of soluble and highly active uridine phosphorylase, (+)-γ-lactamase, and (-)-γ-lactamase in our results shows that the traditional process needs to be reconsidered. Accordingly, a simple and efficient structure-based strategy for the production of valuable soluble recombinant proteins in E. coli is proposed.

Purification, biochemical and kinetic properties of recombinant Staphylococcus aureus lipase

We have compared the purification procedures as well as the biochemical and kinetic properties of wild type (wt-SAL3), untagged recombinant (rec(-His)SAL3), and tagged recombinant (rec(+His)SAL3) purified forms of Staphylococcus aureus lipase (SAL3). We used the pH-stat method (with emulsified tributyrin and olive oil as substrates) and the monomolecular film technique (with the three dicaprin isomers spread in the form of monomolecular films at the air-water interface). The data obtained showed that the recombinant expression process as well as the presence of a his-tag at the N-terminus of recombinant SAL3 affects significantly many biochemical and catalytic properties. The effects of the heterologous expression process on the catalytic properties of the staphylococcal lipases are three times more deleterious than the presence of an N-terminal tag extension.

An overview of enzymatic reagents for the removal of affinity tags

Although they are often exploited to facilitate the expression and purification of recombinant proteins, every affinity tag, whether large or small, has the potential to interfere with the structure and function of its fusion partner. For this reason, reliable methods for removing affinity tags are needed. Only enzymes have the requisite specificity to be generally useful reagents for this purpose. In this review, the advantages and disadvantages of some commonly used endo- and exoproteases are discussed in light of the latest information.

Exploiting the interactions between poly-histidine fusion tags and immobilized metal ions

Immobilized metal affinity chromatography (IMAC) of proteins containing poly-histidine fusion tags is an efficient research tool for purifying recombinant proteins from crude cellular feedstocks at laboratory scale. Nevertheless, to achieve successful purification of large amounts of the target protein for critical therapeutic applications that demand the precise removal of fusion tags, it is important to also take into consideration issues such as protein quality, efficiency, cost effectiveness, and optimal affinity tag choice and design. Despite the many considerations described in this article, it is expected that enhanced selectivity, the primary consideration in the field of protein separation, will continue to see the use of IMAC in solving new purification challenges. In addition, the platform nature of this technology makes it an ideal choice in purifying proteins with unknown properties. Finally, the unique interaction between immobilized metal ions and poly-histidine fusion tag has enabled new developments in the areas of biosensor, immunoassay, and other analytical technologies.

Heterologous expression and N-terminal His-tagging processes affect the catalytic properties of staphylococcal lipases: a monolayer study

The interfacial and kinetic properties of wild type, untagged recombinant and tagged recombinant forms of three staphylococcal lipases (SSL, SXL and SAL3) were compared using the monomolecular film technique. A kinetic study on the dependence of the stereoselectivity of these nine lipase forms on the surface pressure was performed using the three dicaprin isomers spread in the form of monomolecular films at the air-water interface. New parameters, termed Recombinant expression Effects on Catalysis (REC), N-Tag Effects on Catalysis (TEC), and N-Tag and Recombinant expression Effects on Catalysis (TREC), were introduced. The findings obtained showed that with all the lipases tested, the recombinant expression process and the N-terminal His-tag slightly affect the sn-1 preference for dicaprin enantiomers as well as the penetration capacity into monomolecular films of phosphatidylcholine but significantly decrease the catalytic rate of hydrolysis of three dicaprin isomers. This rate reduction is more pronounced at high surface pressures, i.e. at low interfacial energies. In conclusion, the effects of the heterologous expression process on the catalytic properties of the staphylococcal lipases are three times more deleterious than the presence of an N-terminal tag extension. In the case of the situation most commonly encountered in the literature, i.e. the heterologous expression of a tagged lipase, the rate of catalysis can be decreased by these processes by 42-83% on average in comparison with the values measured with the corresponding wild type form.

Staphylococcal lipases stereoselectively hydrolyse the sn-2 position of monomolecular films of diglyceride analogs. Application to sn-2 hydrolysis of triolein

Using the monomolecular film technique, a kinetic study on the stereoselectivity of nine staphylococcal lipase forms was carried out with three pairs of enantiomers from diglyceride analogs (didecanoyl-deoxyamino-O-methyl glycerol, DDG) containing a single hydrolysable decanoyl ester group and two lipase-resistant groups. Our results show that the kinetic profiles of the wild type, the recombinant untagged and the recombinant tagged forms of staphylococcal lipases are significantly different. As with most of the lipases investigated so far, these staphylococcal lipases showed higher catalytic rates with primary esters than with secondary esters. However, it is noteworthy that all these staphylococcal lipases were found to significantly hydrolyse the secondary ester group of diglyceride analogs, with a strong preference for the R configuration. This stereopreference, which was predicted on the basis of Kazlauskas' rule, was comparable to that of Candida rugosa and Pseudomonas glumae lipases. As was to be expected, all the staphylococcal lipases tested efficiently hydrolysed triolein at the sn-2 position. This hydrolytic activity was quantified by performing thin-layer chromatography to analyse the hydrolytic products of triolein. From the qualitative point of view, the sn-2 preferences observed with triolein and diglyceride analogs bearing a secondary ester function were in good agreement. Diglyceride analogs might therefore provide useful initial screening tools for use in future searches for strictly sn-2 specific lipases.