Efficacy and safety of biosimilar trastuzumab (CT-P6) in routine clinical practice in the Republic of Korea: a real-world post-marketing surveillance study.

BACKGROUND: The trastuzumab biosimilar CT-P6 is approved for human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC), metastatic breast cancer (MBC), and metastatic gastric cancer (MGC). The objective of this post-marketing surveillance (PMS) study was to evaluate the real-world safety and effectiveness of CT-P6 in patients with HER2-positive cancers. RESEARCH DESIGN AND METHODS: This open-label, observational, prospective, PMS study collected data via investigator surveys from 35 centers in the Republic of Korea (5 October 2018-4 October 2022). Eligible patients with HER2-positive EBC, MBC, or MGC started CT-P6 treatment during routine clinical practice, followed by 1-year observation. Evaluations included adverse events (AEs), adverse drug reactions (ADRs), and effectiveness. RESULTS: Safety was analyzed in 642 patients (494 EBC, 94 MBC, 54 MGC). Overall, 325 (50.6%) patients experienced 1316 AEs, and 550 ADRs occurred in 199 (31.0%) patients. Unexpected ADRs occurred in 62 (9.7%) patients. Unexpected ADRs and ADRs of special interest did not raise any new safety signals. Among trastuzumab-naïve patients, 34/106 (32.1%) with EBC achieved pathological complete response; 30/74 (40.5%) MBC and 24/49 (49.0%) MGC patients achieved complete or partial response. CONCLUSIONS: In a real-world setting, CT-P6 demonstrated safety and efficacy findings consistent with previous CT-P6 studies.

Efficacy and Safety of CT-P10 Versus Rituximab in Untreated Low-Tumor-Burden Follicular Lymphoma: Final Results of a Randomized Phase III Study.

INTRODUCTION: This double-blind, parallel-group, active-controlled phase III trial (NCT02260804) assessed CT-P10 and rituximab safety and efficacy in patients with previously untreated low-tumor-burden follicular lymphoma (LTBFL), including after a single switch from rituximab to CT-P10. PATIENTS AND METHODS: LTBFL patients were randomized (1:1) to receive CT-P10 or rituximab (375 mg/m2 intravenously; day 1 of 4 7-day cycles). Patients achieving disease control entered a 2-year maintenance period. CT-P10 or rituximab were administered every 8 weeks (6 cycles) in year 1; all patients could receive CT-P10 (every 8 weeks; 6 cycles) in year 2. Secondary endpoints (reported here) were overall response rate (ORR) during the study period, progression-free survival (PFS), time to progression (TTP), and overall survival (OS). Safety and immunogenicity were evaluated. RESULTS: Between  November 9, 2015 and  January 4, 2018, 258 patients were randomized (130 for CT-P10; 128 for rituximab). ORR was similar between groups over the study period (CT-P10: 88%; rituximab: 87%). After 29.2 months' median follow-up, median PFS, TTP, and OS were not estimable; 24-month Kaplan-Meier estimates suggested similarity between groups. Overall, 114 (CT-P10: 88%), and 104 (rituximab: 81%) patients experienced treatment-emergent adverse events. The single switch was well tolerated. CONCLUSION: These updated data support therapeutic similarity of CT-P10 and rituximab and support the use of CT-P10 monotherapy for previously untreated LTBFL.

Engineered Human Ferritin Nanoparticles for Direct Delivery of Tumor Antigens to Lymph Node and Cancer Immunotherapy.

Efficient delivery of tumor-specific antigens (TSAs) to lymph nodes (LNs) is essential to eliciting robust immune response for cancer immunotherapy but still remains unsolved. Herein, we evaluated the direct LN-targeting performance of four different protein nanoparticles with different size, shape, and origin [Escherichia coli DNA binding protein (DPS), Thermoplasma acidophilum proteasome (PTS), hepatitis B virus capsid (HBVC), and human ferritin heavy chain (hFTN)] in live mice, using an optical fluorescence imaging system. Based on the imaging results, hFTN that shows rapid LN targeting and prolonged retention in LNs was chosen as a carrier of the model TSA [red fluorescence protein (RFP)], and the flexible surface architecture of hFTN was engineered to densely present RFPs on the hFTN surface through genetic modification of subunit protein of hFTN. The RFP-modified hFTN rapidly targeted LNs, sufficiently exposed RFPs to LN immune cells during prolonged period of retention in LNs, induced strong RFP-specific cytotoxic CD8+ T cell response, and notably inhibited RFP-expressing melanoma tumor growth in live mice. This suggests that the strategy using protein nanoparticles as both TSA-carrying scaffold and anti-cancer vaccine holds promise for clinically effective immunotherapy of cancer.

Adjuvant effect of B domain of staphyloccocal protein A displayed on the surface of hepatitis B virus capsid.

The hepatitis B virus (HBV) capsid-based recombinant particles, which display both major hydrophilic region of HBV surface antigen (HBV-MHR) and B domain of Staphylococcal protein A (SPAB ), were produced using Escherichia coli as expression host. SPAB was used as an adjuvant to elicit the immune response to HBV-MHR, and its adjuvant effect in the immunized mice was estimated with varying the position and amount of SPAB on the HBV capsid particles. Compared to the emulsified aluminum gel (alum gel) that is a currently commercialized vaccine adjuvant, SPAB caused the significantly higher level of anti-HBV immunoglobulin G (IgG) titer and seroconversion rate, and notably SPAB at the most surface-exposed position on the recombinant particle led to the highest immune response. Moreover, SPAB caused much lower ratio of IgG1 to IgG2a compared to alum gel, indicating that helper T-cell 1-mediated immune response (responsible for cytotoxic T-cell stimulation) is relatively more stimulated by SPAB , unlike alum gel that mainly stimulates helper T-cell 2-mediated immune response (responsible for B-cell stimulation). Although HBV-MHR and HBV capsid particle were used as proof-of-concept in this study, SPAB can be used as a highly effective adjuvant with other disease-specific antigens on the surface of other virus-like particles to produce various recombinant vaccines with high potency.

Self-assembled proteinticle nanostructures for 3-dimensional display of antibodies.

"Proteinticle" is a nano-scale protein particle that is self-assembled inside cells with constant 3D structure and surface topology. The binding of IgG to the B domain of Staphylococcal protein A (SPA(B)) molecules that are genetically inserted on the surface of proteinticle enables the variable domains of bound IgG to be well oriented to effectively capture antigens, accordingly forming a highly sensitive 3D IgG probe. The five different proteinticles that originate from humans, bacteria, and virus and totally differ in size, shape, and surface structure were used for the surface display of SPA(B). The dissociation constant (K(D)) in the binding of IgG to SPA(B) on the proteinticle surface was estimated based on the Langmuir adsorption isotherm model: K(D) was 1-3 orders-of-magnitude lower compared to the previously reported K(D) in the binding of IgG to Staphylococcal protein A. The surface density and distribution of SPA(B) and especially the existence of hot (or highly congested) spots of SPA(B), which depend on the surface structure and the number of subunits as well as size and shape of proteinticle, is of crucial importance for the effective binding of IgG to SPA(B) on proteinticles. Although the five different proteinticles were demonstrated as proof-of-concept here, SPA(B)-mediated immobilization of IgG on the other proteinticles would be very useful for the fabrication of sensitive 3D immunoassay platforms.

Synthesis of Mycoplasma arginine deiminase in E. coli using stress-responsive proteins.

We found Escherichia coli proteins, elongation factor Ts (Tsf), and malate dehydrogenase (Mdh) that can exist in the form of native and soluble proteins even under stress situation such as heat shock and protein denaturing condition. To examine their property as solubility enhancers, aggregation-prone Mycoplasma arginine deiminase (mADI), which has been suggested as anti-cancer agent, was fused to the C-terminal of each of them and cloned into pET28a to be expressed in the E. coli cytoplasm. When mADI was fused to fusion partners (Mdh, Tsf), a significant portion of the recombinant mADI was expressed in a soluble fraction (>90%) whereas the directly expressed mADI was aggregated to the inclusion body. In addition, recombinant mADI released from the fusion tag retained its soluble form and presented its specific enzymatic activity of converting l-arginine into citrulline (>10 U/mg). These results show that Tsf and Mdh could serve as effective solubility enhancers for aggregation-prone proteins (e.g. mADI in this case) when used as fusion expression partners in bacterial expression systems.

Engineered protein nanoparticles for in vivo tumor detection.

Two different protein nanoparticles that are totally different in shape and surface structure, i.e. Escherichia coli DNA-binding protein (eDPS) (spherical, 10 nm) and Thermoplasma acidophilum proteasome (tPTS) (cylindrical, 12 × 15 nm) were engineered for in vivo optical tumor detection: arginine-glycine-aspartic acid (RGD) peptide (CDCRGDCFC) was genetically inserted to the surface of each protein nanoparticle, and also near-infrared fluorescence dye was chemically linked to the surface lysine residues. The specific affinity of RGD for integrin (αvß3) facilitated the uptake of RGD-presenting protein nanoparticles by integrin-expressing tumor cells, and also the protein nanoparticles neither adversely affected cell viability nor induced cell damage. After intravenously injected to tumor-bearing mice, all the protein nanoparticles successfully reached tumor with negligible renal clearance, and then the surface RGD peptides caused more prolonged retention of protein nanoparticles in tumor and accordingly higher fluorescence intensity of tumor image. In particular, the fluorescence of tumor image was more intensive with tPTS than eDPS, which is due presumably to longer in vivo half-life and circulation of tPTS that originates from thermophilic and acidophilic bacterium. Although eDPS and tPTS were used as proof-of-concept in this study, it seems that other protein nanoparticles with different size, shape, and surface structure can be applied to effective in vivo tumor detection.

A simple one-step assay platform based on fluorescence quenching of macroporous silicon.

We synthesized 3D macroporous silicon through a simple electrochemical dissolution process and systematically estimated its protein adsorption and effect on fluorescence emission. Compared with conventional 2D polystyrene plate, the macroporous silicon showed a superior protein adsorption capacity and significant fluorescence quenching effect. We developed a 3D macroporous silicon-based adenosine assay system through the following fabrication process: streptavidin molecules that have been immobilized on the surface of macroporous silicon are attached with biotin-linked and adenosine-specific DNA aptamer, followed by hybridization between the attached aptamer and fluorescent chemical (carboxytetramethylrhodamine/CTMR) that is conjugated with a short complementary DNA sequence. In the absence of adenosine, the aptamer-CTMR complexes remain closely attached to the surface of porous silicon, hence fluorescence being significantly quenched. Upon binding to adenosine, the DNA aptamer is subject to structure switching that leads to dissociation of CTMR from DNA aptamer, and consequently the CTMR fluorescence is restored, indicating a simple one-step assay of adenosine. Compared to the conventional 2D PS and ZnO nanorods-based assays, adenosine at much lower (sub-micromolar) concentration was successfully detected through the 3D macroporous silicon-based assay. The three-dimensionally and densely immobilized aptamer probes and effective fluorescence quenching on the surface of macroporous silicon enables adenosine to be detected at lower levels. Although the adenosine detection is reported here as a proof-of-concept, the developed macroporous silicon-based simple one-step assay platform can be applied in general to fluorescence quenching -based detection of many other biomolecules.

YrhB is a highly stable small protein with unique chaperone-like activity in Escherichia coli BL21(DE3).

Escherichia coli YrhB (10.6 kDa) from strain BL21(DE3) that is commonly used for protein overexpression is a stable chaperone-like protein and indispensable for supporting the growth of BL21(DE3) at 48 °C but not defined as conventional heat shock protein (HSP). YrhB effectively prevented heat-induced aggregation of ribonucleotide synthetase (PurK). Without ATP, YrhB alone promoted in vitro refolding of uridine phosphorylase (UDP) and protected thermal denaturation of the refolded UDP. As a cis-acting fusion partner, YrhB also significantly reduced inclusion body formation of nine aggregation-prone heterologous proteins in BL21(DE3). Unlike conventional small HSPs, YrhB remained monomer under heat shock condition.

A sensitive diagnostic assay of rheumatoid arthritis using three-dimensional ZnO nanorod structure.

We synthesized a three-dimensional nanorod structure of zinc oxide (ZnO) using a simple sol-gel process and systematically investigated properties of the ZnO nanorods regarding protein adsorption and effect on fluorescence emission. As compared to conventional polystyrene plate that has been widely used for strong protein adsorption, the ZnO nanorods had a superior protein adsorption capacity and significantly amplified fluorescence emission, suggesting the ZnO nanorods are attractive for fluorescence-based biomolecular detection assays. When applied to diagnostic assay of rheumatoid arthritis (RA) using cyclic citrullinated peptide (CCP) probe with a RCGRS motif that reportedly has a strong affinity for ZnO, the ZnO nanorods gave apparently high positive signals for all the RA-positive standards and patient sera, whereas upon the detection using conventional polystyrene plate, all the detection signals were relatively negligible. Moreover, the streptavidin-mediated immobilization of well oriented CCP further enhanced sensitivity, even for a 5000-times diluted patient serum. A highly sensitive detection of a very small amount of RA autoantibodies is important because individuals at high risk of developing RA can be identified several years before the clinical onset. Consequently, the fluorescence-based sensitive assay of RA was successfully performed using the three-dimensional ZnO nanorods, owing to the fluorescence amplification and protein/peptide adsorption properties and dimensionality of ZnO nanorods that in turn increases probe accessibility to anti-CCP RA autoantibodies. Although RA was assayed here for proof-of-concept, the ZnO nanorods-based assay can be applied in general to sensitive detection of a wide variety of antibody or protein targets.

Fluorescent ferritin nanoparticles and application to the aptamer sensor.

We synthesized fluorescent ferritin nanoparticles (FFNPs) through bacterial expression of the hybrid gene consisting of human ferritin heavy chain (hFTN-H), spacer (glycine-rich peptide), and enhanced green (or red) fluorescent protein [eGFP (or DsRed)] genes. The self-assembly activity of hFTN-H that leads to the formation of nanoparticles (12 nm in diameter), the conformational flexibility of the C-terminus of hFTN-H, and the glycine-rich spacer enabled eGFPs (or DsReds) to be well displayed on the surface of each ferritin nanoparticle, resulting in the construction of green (or red) FFNPs [gFFNPs (or rFFNPs)]. As compared to eGFP (or DsRed) alone, it is notable that the developed FFNPs showed significantly amplified fluorescence intensity and also enhanced stability. DNA aptamers were chemically conjugated to gFFNP via each eGFP's cysteine residue that was newly introduced through site-directed mutagenesis (Ser175Cys). The DNA-aptamer-conjugated gFFNPs were used as a fluorescent reporter probe in the aptamer-based "sandwich" assay of a cancer marker [i.e., platelet-derived growth factor B-chain homodimer (PDGF-BB)] in phosphate-buffered saline buffer or diluted human serum. This is a simple two-step assay without any additional steps for signal amplification, showing that compared to the same aptamer-based assays using eGFP alone or Cy3, the detection signals, affinity of the reporter probe to the cancer marker, and assay sensitivity were significantly enhanced; i.e., the limit of detection was lowered to the 100 fM level. Although the PDGF-BB assay is reported here as a proof-of-concept, the developed FFNPs can be applied in general to any aptamer-based sandwich assays.

Lyophilization and enhanced stability of fluorescent protein nanoparticles.

Protein nanoparticles (PNPs) that are nanostructured biomaterials with intrinsic biological function have been widely employed as three-dimensional nanobiomaterials for sensitive bioassays, MRI contrast, semiconductor devices, template for hybrid materials, etc., and stable and long-term maintenance of PNPs seems to be of crucial importance. We evaluated the stability of PNPs and the efficacy of lyophilization for the long-term stability of PNPs, especially using green fluorescent protein nanoparticles (gFPNPs) as a model PNP. Fluorescence intensities and TEM images of gFPNPs were analyzed to monitor their functional and structural stabilities. Unlike the green fluorescent protein monomers (eGFP) that were gradually inactivated in aqueous solution, gFPNP in the same aqueous solution retained the initial fluorescence activity and spherical nanoparticle structure even for 2 weeks at 4°C. To ensure stable and long-term maintenance of gFPNPs, gFPNPs in aqueous solution were converted to the dried solid forms through lyophilization. It is notable that fluorescence activity and nanoparticle structure of gFPNPs that were lyophilized with both Tween 80 and sucrose were very stably maintained even for 10weeks at various storage temperatures (-20°C, 4°C, 25°C, and 37°C). During the period of 10weeks, the fluorescence of gFPNP was always more than 80% level of initial fluorescence at a wide range of temperature. Although this stability study was focused on gFPNPs, the developed optimal lyophilization conditions for gFPNPs can be applied in general to stable and long-term maintenance of many other PNP-derived biomaterials.

Human G-CSF synthesis using stress-responsive bacterial proteins.

We previously reported that under the stress condition caused by the addition of 2-hydroxyethyl disulfide, a thiol-specific oxidant, to growing cultures of Escherichia coli BL21(DE3), a population of stress-responsive proteins [peptidyl-prolyl cis-trans isomerase B (PpiB), bacterioferritin (Bfr), putative HTH-type transcriptional regulator yjdC (YjdC), dihydrofolate reductase (FolA), chemotaxis protein cheZ (CheZ), and glutathione synthetase (GshB)] were significantly upregulated when compared with the nonstress condition. When those stress-responsive proteins were used as fusion partners for the expression of human granulocyte colony-stimulating factor (hG-CSF), the solubility of hG-CSF was dramatically enhanced in E. coli cytoplasm, whereas almost all of the directly expressed hG-CSF were aggregated to inclusion bodies. In addition, the spectra of circular dichroism measured with the purified hG-CSF were identical to that of standard hG-CSF, implying that the synthesized hG-CSF has native conformation. These results indicate that the bacterial stress-responsive proteins could be potent fusion expression partners for aggregation-prone heterologous proteins in E. coli cytoplasm.

A highly sensitive and selective diagnostic assay based on virus nanoparticles.

Early detection of the protein marker troponin I in patients with a higher risk of acute myocardial infarction can reduce the risk of death from heart attacks. Most troponin assays are currently based on the conventional enzyme linked immunosorbent assay and have detection limits in the nano- and picomolar range. Here, we show that by combining viral nanoparticles, which are engineered to have dual affinity for troponin antibodies and nickel, with three-dimensional nanostructures including nickel nanohairs, we can detect troponin levels in human serum samples that are six to seven orders of magnitude lower than those detectable using conventional enzyme linked immunosorbent assays. The viral nanoparticle helps to orient the antibodies for maximum capture of the troponin markers. High densities of antibodies on the surfaces of the nanoparticles and nanohairs lead to greater binding of the troponin markers, which significantly enhances detection sensitivities. The nickel nanohairs are re-useable and can reproducibly differentiate healthy serum from unhealthy ones. We expect other viral nanoparticles to form similar highly sensitive diagnostic assays for a variety of other protein markers.

Multiple stressor-induced proteome responses of Escherichia coli BL21(DE3).

Through 2-DE based quantitative proteomics, the dynamic characteristics of overall proteome profiles of Escherichia coli BL21(DE3) were systematically analyzed in the presence of four different stressors. Dithiothreitol and 2-hydroxyethyl disulfide are a reducing and an oxidizing agent, respectively, which disturb the redox balance in cytoplasm, while guanidine hydrochloride and heat shock are protein denaturants influencing protein folding. Heat shock proteins/foldases, transcription/translation-related proteins, various metabolic enzymes, and other stress regulatory proteins were found to be significantly up-regulated in response to the stressors. Heat shock proteins and translation-related proteins were generally responsive to almost all stress conditions. Two stressors, oxidative stress and guanidine hydrochloride-derived protein denaturation commonly induced the up-regulation of proteins related to transcription, whereas metabolic enzymes showed stress responses especially to the treatment of guanidine hydrochloride and heat shock. Similarities and differences of stress responses and protein-protein interactions of 80 proteins were systematically compared, and of special note, proteome-based stress-responsive proteins identified in the present study included 26 proteins that are being reported for the first time. The quantitative and systematic proteome analyses that we have performed provide more detailed information on E. coli BL21(DE3), a widely used host strain for recombinant protein overexpression.

Solubility enhancement of aggregation-prone heterologous proteins by fusion expression using stress-responsive Escherichia coli protein, RpoS.

BACKGROUND: The most efficient method for enhancing solubility of recombinant proteins appears to use the fusion expression partners. Although commercial fusion partners including maltose binding protein and glutathione-S-transferase have shown good performance in enhancing the solubility, they cannot be used for the proprietory production of commercially value-added proteins and likely cannot serve as universal helpers to solve all protein solubility and folding issues. Thus, novel fusion partners will continue to be developed through systematic investigations including proteome mining presented in this study. RESULTS: We analyzed the Escherichia coli proteome response to the exogenous stress of guanidine hydrochloride using 2-dimensional gel electrophoresis and found that RpoS (RNA polymerase sigma factor) was significantly stress responsive. While under the stress condition the total number of soluble proteins decreased by about 7 %, but a 6-fold increase in the level of RpoS was observed, indicating that RpoS is a stress-induced protein. As an N-terminus fusion expression partner, RpoS increased significantly the solubility of many aggregation-prone heterologous proteins in E. coli cytoplasm, indicating that RpoS is a very effective solubility enhancer for the synthesis of many recombinant proteins. RpoS was also well suited for the production of a biologically active fusion mutant of Pseudomonas putida cutinase. CONCLUSION: RpoS is highly effective as a strong solubility enhancer for aggregation-prone heterologous proteins when it is used as a fusion expression partner in an E. coli expression system. The results of these findings may, therefore, be useful in the production of other biologically active industrial enzymes, as successfully demonstrated by cutinase.

Solubilization of aggregation-prone heterologous proteins by covalent fusion of stress-responsive Escherichia coli protein, SlyD.

The proteome profile of Escherichia coli BL21(DE3) generated in response to heat shock stress was analyzed by two-dimensional electrophoresis (2-DE), wherein we identified a FKBP-type peptidyl-prolyl cis-trans isomerse (PPIases), SlyD, as a stress-responsive (i.e. aggregation-resistant) protein. Even under an imposed severe stress condition where 29 out of 858 soluble proteins were totally eliminated and the synthesis levels of 171 proteins decreased over 5-fold, a 3.37-fold increase induced by heat shock treatment was observed in the synthesis level of SlyD compared with a non-stress condition. As a fusion partner, as well as solubility enhancer, SlyD facilitated folding and significantly increased the solubility of many aggregation-prone heterologous proteins in E. coli cytoplasm. SlyD was very effective in sequestering interactive surfaces of heterologous proteins associated with non-specific protein-protein interactions and the formation of inclusion bodies, most likely as a result of intrinsic folding efficiencies and/or chaperone-like activities. SlyD was also shown to be suitable for the production of a biologically active fusion mutant of Pseudomonas putida cutinase that is of considerable biotechnological and commercial interest.

Transport proteins PotD and Crr of Escherichia coli, novel fusion partners for heterologous protein expression.

The Escherichia coli proteome response to the stressor GdnHCl was analyzed through 2-dimensional gel electrophoresis (2-DE). We identified PotD (spermidine/putrescine-binding periplasmic protein) and Crr [glucose-specific phosphotransferase (PTS) enzyme IIA component] as a stress-responsive protein. Even under a stress situation where the total number of soluble proteins decreased by about 10%, 3.5- and 2.2-fold increase was observed in the synthesis of PotD and Crr, respectively. As fusion partners, PotD and Crr dramatically increased the solubility of many aggregation-prone heterologous proteins [e.g. human minipro-insulin (mp-INS), human epidermal growth factor (EGF), human prepro-ghrelin (ppGRN), human interleukin-2(hIL-2), human activation induced cytidine deaminase (AID), human glutamate decarboxylase (GAD(448-585)), Pseudomonas putida cutinase (CUT), human ferritin light chain (hFTN-L), human granulocyte colony-stimulating factor (G-CSF), and cold autoinflammatory syndrome1 protein (NALP3) Nacht domain (NACHT)] in the E. coli cytoplasm. Presumably PotD and Crr were very effective in shielding interactive surfaces of heterologous proteins associated with non-specific protein-protein interactions leading to the formation of inclusion bodies most likely due to intrinsic high folding efficiency, chaperone-like activity, or a combination of both factors. Both the stress-induced proteins were well suited for the production of a biologically active fusion mutant of P. putida cutinase that can be expected to be of biotechnological and commercial interest.

Enhanced solubility of heterologous proteins by fusion expression using stress-induced Escherichia coli protein, Tsf.

Through two-dimensional electrophoresis, Escherichia coli proteome response to a protein denaturant, guanidine hydrochloride, was analyzed and elongation factor Ts (Tsf) detected as a stress-induced protein. Many host proteins aggregated, or their synthesis levels decreased significantly under conditions of protein denaturation as 34 out of 699 soluble proteins knocked out and 63 proteins decreased by over 2.5-fold. Interestingly, the expression level of Tsf increased 1.61-fold compared with a nonstress condition. Contrary to direct expression, various heterologous proteins were solubly expressed in E. coli when subjected to N-terminus fusions of Tsf. Owing most likely to an intrinsic high folding efficiency, Tsf seemed to play critical roles in sequestering interactive surfaces of heterologous proteins from nonspecific protein-protein interactions leading to formation of inclusion bodies. It has been also demonstrated that Tsf is effective in aiding the production of a biologically active bacterial cutinase, which could be of interest to biotechnology and commercial applications.