Recombinant human serum amyloid P component from Pichia pastoris: production and characterization

Bioprocess development for extracellular production of recombinant human interleukin-3 (hIL-3) in Pichia pastoris

Human interleukin-3 (hIL-3) is a therapeutically important cytokine involved in the maturation and differentiation of various cells of the immune system. The codon-optimized hIL-3 gene was cloned in fusion with the N-terminus α-mating factor signal peptide of Saccharomyces cerevisiae under an inducible alcohol oxidase 1 (AOX1) and constitutive glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter. A Zeocin concentration up to 2000 mg/L was used to select hyper-producers. The shake flask cultivation studies in the Pichia pastoris GS115 host resulted a maximum recombinant hIL-3 expression level of 145 mg/L in the extracellular medium under the control of AOX1 promoter. The batch fermentation strategy allowed us to attain a fairly pure glycosylated hIL-3 protein in the culture supernatant at a final concentration of 475 mg/L with a high volumetric productivity of 4.39 mg/L/h. The volumetric product concentration achieved at bioreactor level was 3.28 folds greater than the shake flask results. The 6x His-tagged protein was purified using Ni–NTA affinity chromatography and confirmed further by western blot analysis using anti-6x His tag antibody. The glycosylation of recombinant hIL-3 protein was confirmed in a PNGase F deglycosylation reaction where it showed a molecular weight band pattern similar to E. coli produced non-glycosylated hIL-3 protein. The structural properties of recombinant hIL-3 protein were confirmed by CD and fluorescence spectroscopy where protein showed 40 % α-helix, 12 % β-sheets with an emission maxima at 343 nm. MALDI-TOF-TOF analysis was used to establish the protein identity. The biological activity of purified protein was confirmed by the human erythroleukemia TF-1 cell proliferation assay.

Trehalose-6-phosphate synthase 1 from Metarhizium anisopliae: clone, expression and properties of the recombinant

Trehalose, an important component in fungal spores, is a disaccharide which protects against several environmental stresses, such as heat, desiccation, salt. Trehalose-6-phosphate synthase 1 (TPS1) is a subunit of trehalose synthase complex in fungi; it plays a key role in the biosynthesis of trehalose. In this study, a full-length cDNA from Metarhizium anisopliae encoding TPS1 (designated as MaTPS1) was isolated. The MaTPS1 cDNA is composed of 1836 nucleotides encoding a protein of 517 amino acids with a molecular mass of 58 kDa. The amino acid sequence has a relatively high homology with the TPS1s in several other filamentous fungi. Southern blot analysis showed that MaTPS1 gene occurs as a single copy in the M. anisopliae genome. And MaTPS1 was cloned into Pichia pastoris KM71 and secretively expressed with a histamine tag to facilitate a rapid purification of recombinant MaTPS1 (designated reTPS1). The properties of reTPS1 were examined. The K(m) value of reTPS1 for UDP-glucose and glucose-6-phosphate was 9.6 mM and 3.9 mM, respectively, and the optimal pH and temperature were about 6.5 and 40 degrees C. The enzyme was highly specific to glucose-6-phosphate for glucosyl acceptor, and its activity decreased rapidly as the concentrations of phosphate increased. The expression system will provide sufficient amounts of reTPS1 for future structural characterization of the protein and use for further investigation of MaTPS1's function.

Expression, purification, and characterization of recombinant Metarhizium anisopliae acid trehalase in Pichia pastoris

The mature peptide of Metarhizium anisopliae acid trehalase (ATM1) (EC3.2.1.28) was successfully expressed in Pichia pastoris at high levels under the control of AOX1 promoter. The recombinant ATM1 (reATM1) was secreted into culture medium. After 48-h 0.5% methanol induction, the activity of reATM1 in the culture supernatant reached the peak, 5.35 U/mg. Enzyme with a histidine sequence appended to the C terminus was still active and was purified using metal-chelate affinity chromatography. The yield of purified reATM1 was 2.5 mg from 1L supernatant. The purified reATM1 exhibited a molecular mass of approximately 170 kDa on SDS-PAGE. The optimum temperature and pH of reATM1 were 30 degrees C and 6.0, respectively, and the K(m) and V(max) values for reATM1 were 2.6 mM and 0.305 mmol/min/mg, respectively. Studies showed that the enzymatic properties of reATM1 were similar to those of the native ATM1.

Improved yields of full-length functional human FGF1 can be achieved using the methylotrophic yeast Pichia pastoris

We have produced human fibroblast growth factor 1 (hFGF1) in the methylotrophic yeast Pichia pastoris in order to obtain the large amounts of active protein required for subsequent functional and structural characterization. Four constructs were made to examine both intracellular and secreted expression, with variations in the location of the His6 tag at either end of the peptide. hFGF1 could be produced from all four constructs in shake flasks, but production was optimized by growing only the highest-yielding of these strains, which produced hFGF1 intracellularly, under tightly controlled conditions in a 3 L fermentor. One hundred and eight milligrams of pure protein was achieved per liter culture (corresponding to 0.68 mg of protein per gram of wet cells), the function of which was verified using NIH 3T3 cell cultures. This is a 30-fold improvement over previously reported yields of full-length hFGF1.

Serum amyloid P-component in murine tuberculosis: induction kinetics and intramacrophage Mycobacterium tuberculosis growth inhibition in vitro

Serum amyloid P-component (SAP), a pentraxin, is known to play an important role in innate immunity to microbial infections; however, nothing is known about it during tuberculosis (TB). Mice intratracheally infected with Mycobacterium tuberculosis Erdman, showed peak SAP levels (442+/-58.2 microg/ml) on day 21, which declined to background levels by day 60. Their serum interleukin-6 levels paralleled SAP levels, whereas, their serum transforming growth factor-beta levels were paradoxical. During the acute phase of infection, the SAP levels positively correlated with the lung mycobacterial load. Purified mouse SAP (1-50 microg/ml) treatment of M. tuberculosis-infected alveolar macrophages (AMs), in vitro, inhibited their intracellular mycobacterial growth; maximum inhibition (1.1 log10 CFU reduction) occurred at 10 microg/ml, and a 4-day treatment appeared optimal. Treatment of AMs with both rabbit anti-mouse SAP polyclonal antibody and mannose-derived simple sugars, separately, blocked the SAP-induced inhibition of mycobacterial growth. The mycobacterial growth inhibition appeared to be nitric oxide (NO)-dependent as NO synthase inhibitors, both aminoguanidine and N(G)-monomethyl-L-arginine, annulled it. Further, SAP treatment of infected AMs induced significant (P<0.05) elaboration of nitrite (72.1+/-8.3 nM/ml), compared to the controls, and these AMs showed augmented expression of inducible NO synthase. This first study demonstrates that during murine TB the SAP levels were increased, and purified mouse SAP inhibited the intra-AM M. tuberculosis growth, in vitro, apparently via NO-dependent mechanism(s). SAP may thus contribute both to the pathogenesis and pulmonary innate immunity in TB.

Heterologous protein production using thePichia pastoris expression system

The Pichia pastoris expression system is being used successfully for the production of various recombinant heterologous proteins. Recent developments with respect to the Pichia expression system have had an impact on not only the expression levels that can be achieved, but also the bioactivity of various heterologous proteins. We review here some of these recent developments, as well as strategies for reducing proteolytic degradation of the expressed recombinant protein at cultivation, cellular and protein levels. The problems associated with post-translational modifications performed on recombinant proteins by P. pastoris are discussed, including the effects on bioactivity and function of these proteins, and some engineering strategies for minimizing unwanted glycosylations. We pay particular attention to the importance of optimizing the physicochemical environment for efficient and maximal recombinant protein production in bioreactors and the role of process control in optimizing protein production is reviewed. Finally, future aspects of the use of the P. pastoris expression system are discussed with regard to the production of complex membrane proteins, such as G protein-coupled receptors, and the industrial and clinical importance of these proteins.