Design of Agents Interacting with Immunoregulating Proteins:Potential Inhibitors of the Phenylpyruvate Tautomerase Activity Catalysed by Macrophage Migration Inhibitory Factor (MIF)

The macrophage migration inhibitory factor has been implicated in a number ofimmune and inflammatory processes. MIF presents particular opportunities for drug design anddevelopment with potential therapeutic applications. Drug design strategies taking intoconsideration of specific stereochemical and tautomeric requirements in the interaction of MIF withsubstrates and inhibitors allow several novel structures to be designed. Our investigationssuccessfully explored the tautomeric and stereochemical aspects of new compounds of the2-phenylpyruvic acid type, both experimentally, through synthesis and structural investigations andcomputationally, through molecular mechanics and quantum mechanics calculations.

Reconstruction of tyrosol synthetic pathways in Escherichia coli

Tyrosol is a pharmacologically active phenolic compound widely used in the medicine and chemical industries.Traditional methods of plant extraction are complicated and chemical synthesis of tyrosol is not commercially viable. In this study, a recombinant Escherichia coli strain was constructed by overexpressing the phenylpyruvate decarboxylase ARO10 from Saccharomyces cerevisiae, which could produce tyrosol from glucose. Furthermore,genes encoding key enzymes from the competing phenylalanine and tyrosine synthesis pathways and the repression protein TyrR were eliminated, and the resulting engineered strain generated 3.57 mmol·L^(-1) tyrosol from glucose. More significantly, codon optimization of ARO10 increased expression and tyrosol titer. Using the novel engineered strain expressing codon-optimized AR10 in shake-flask culture, 8.72 mmol·L^(-1) tyrosol was obtained after 48 h. Optimization of the induction conditions improved tyrosol production to 9.53 mmol·L^(-1)(1316.3 mg·L^(-1)). A higher titer of tyrosol was achieved by reconstruction of tyrosol synthetic pathway in E. coli.

Hydrogenation of phenylpyruvic acid to phenylalanine catalyzed by Ni-B/SiO_2

Phenylalanine （Phe） is a significant amino acid that cannot be synthesized by human themselves but must be taken from environment. It was initially found that the nanosized amorphous Ni-B/SiO2 alloy prepared by the chemical reduction method was an effective catalyst for the preparation of Phe from phenylpyruvic acid （PPA） by amination and hydrogenation. It has been found that the amorphous Ni-B/SiO2 alloy catalyst exhibits superior activity and selectivity to the traditional catalysts Raney Ni and Urushibara nickel. The effects of reaction time, amounts of catalysts and ammonia solution, reaction temperature, and H2 pressure on the reaction have been investigated systematically. The results indicated that the yield of Phe was 97.9%, and the selectivity for Phe reached 98.9% when the reaction was carried out for 3 h at 333 K and 2.0 MPa of H2 with m（Cat.） ： m（PPA） = 0.6 ： 1.0 and n（NH3） ： n（PPA） = 3 ： 1. The catalysts were characterized by XRD, AAS, XPS, BET, and TEM, and the relationship between the catalyst structure and the catalytic activity was discussed in detail. It was found that the reason why Ni-B/SiO2 amorphous alloy catalyst was much more active for the preparation of Phe could be accounted for by the presence of electron-rich Ni due to electron donation from alloying B; the smaller size of Ni-B particles, the larger specific surface area of Ni-B/SiO2.

A metabolite from commensal Candida albicans enhances the bactericidal activity of macrophages and protects against sepsis

The gut microbiome is recognized as a key modulator of sepsis development.However,the contribution of the gut mycobiome to sepsis development is still not fully understood.Here,we demonstrated that the level of Candida albicans was markedly decreased in patients with bacterial sepsis,and the supernatant of Candida albicans culture significantly decreased the bacterial load and improved sepsis symptoms in both cecum ligation and puncture(CLP)-challenged mice and Escherichia coli-challenged pigs.Integrative metabolomics and the genetic engineering of fungi revealed that Candida albicans-derived phenylpyruvate(PPA)enhanced the bactericidal activity of macrophages and reduced organ damage during sepsis.Mechanistically,PPA directly binds to sirtuin 2(SIRT2)and increases reactive oxygen species(ROS)production for eventual bacterial clearance.Importantly,PPA enhanced the bacterial clearance capacity of macrophages in sepsis patients and was inversely correlated with the severity of sepsis in patients.Our findings highlight the crucial contribution of commensal fungi to bacterial disease modulation and expand our understanding of the host-mycobiome interaction during sepsis development.

Enzymatic properties and inhibition tolerance analysis of key enzymes inβ-phenylethanol anabolic pathway of Saccharomyces cerevisiae HJ

Huangjiu is known for its unique aroma,primarily attributed to its high concentration ofβ-phenylethanol(ranging from 40 to 130 mg/L).Phenylalanine aminotransferase Aro9p and phenylpyruvate decarboxylase Aro10p are key enzymes in theβ-phenylethanol synthetic pathway of Saccharomyces cerevisiae^(HJ).This study examined the enzymatic properties of these two enzymes derived from S.cerevisiae^(HJ)and^(S288C).After substrate docking,Aro9p^(HJ)(-24.05 kJ/mol)and Aro10p^(HJ)(-14.33 kJ/mol)exhibited lower binding free energies compared to Aro9p^(S288C)(-21.93 kJ/mol)and Aro10p^(S288C)(-12.84 kJ/mol).ARO9 and ARO10 genes were heterologously expressed in E.coli BL21.Aro9p,which was purified via affinity chromatography,showed inhibition by L-phenylalanine(L-PHE),but the reaction rate Vmax(Aro9p^(HJ):23.89μmol⋅(min·g)^(-1)>Aro9p^(S288C):21.3μmol⋅(min·g)^(-1))and inhibition constant Ki values(Aro9p^(HJ):0.28 mol L^(-1)>Aro9p^(S288C)0.26 mol L^(-1))indicated that Aro9p from S.cerevisiae^(HJ)was more tolerant to substrate stress during Huangjiu fermentation.In the presence of the same substrate phenylpyruvate(PPY),Aro10p^(HJ)exhibited a stronger affinity than Aro10p^(S288C).Furthermore,Aro9p^(HJ)and Aro10p^(HJ)were slightly more tolerant to the final metabolitesβ-phenylethanol and ethanol,respectively,compared to those from^(S288C).The study suggests that the mutations in Aro9p^(HJ)and Aro10p^(HJ)may contribute to the increasedβ-phenylethanol concentration in Huangjiu.This is the first study investigating enzyme tolerance mechanisms in terms of substrate and product,providing a theoretical basis for the regulation of theβ-phenylethanol metabolic pathway.

Biosynthesis of(R)-2-hydroxy-3-phenylpropionic acid using whole recombinant Escherichia coli cells in an aqueous/n-octane biphasic system

（R）-2-hydroxy-3-phenylpropionic acid （PIP,） is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bioconversion of phenylpyruvate （PPA） to PLA using whole recombinant Escherichia coli cells in a series of buffer/organic solvent systems. Octane was found to be the best organic solvent. The optimum volume ratio of the water phase to the n-octane phase, conversion temperature, substrate concentration, and cell concentration were 6：4, 40 ℃, 12.5 g/L, and 30 g/L wet cells, respectively. Under the optimized conditions, the average PLA productivity in the aqueous/ n-octane system was 30.69% higher than that in the aqueous system, and 32.31 g/L PLA was obtained with the use of a stirred reactor （2-L scale）. Taken together, our findings indicated that PLA biosynthesis was more efficient in an aqueous/n-octane biphasic system than in a monophasic aqueous system. The proposed biphasic system is an effective strategy for enhancing PLA yield and the biosynthesis of its analogues.