Molecular cloning, expression and purification of muscle fructose-1,6-bisphosphatase from Zaocys dhumnades: the role of the N-terminal sequence in AMP activation at alkaline pH

Efficacy and safety of Chinese patent medicine compound preparation combined with routine treatment in vitiligo: A Bayesian network meta-analysis

BACKGROUND AND PURPOSE

Treating vitiligo in clinical practice is challenging. Furthermore, oral drugs used in Western medicine have considerable side effects and are unsuitable for long-term treatment. In contrast, Chinese patent medicines (CPMs) are more suitable for long-term oral vitiligo treatment, but medical evidence of their efficacy and safety is lacking. Therefore, in this study, the efficacy and safety of CPMs were evaluated and ranked using a Bayesian network meta-analysis.

METHODS

Seven Chinese and English databases were searched for all relevant articles published up to February 2023. The Bayesian network meta-analysis method was used to analyze the extracted data to evaluate efficacy and safety.

RESULTS

Six common CPMs for treating vitiligo were selected in our study, and 48 targeted articles and 4446 patients were included. This study showed that Qubai Babuqi tablets (QT) were the most effective for short-term treatment of vitiligo, and that vitiligo capsules or pills (VCP) were the most effective for long-term treatment, together with compound Quchong Banjiuju pills (QP). In terms of surface area under the cumulative ranking curve (SUCRA) values, the order of efficacy of each treatment was as follows: QT (92.18%) > Taohong Qingxue pills (TP) (63.81%) > VCP (55.53%) > QP (50.72%) > Bailing tablets or capsules (BTC) (49.01%) > Baishi pills (BP) (35.69%)>routine therapy (RT) (3.1%) in terms of total effective rate and QT (92.05%) > VCP (71.50%) > QP (66.60%) > TP (42.95%) > BTC (39.66%) > BP (36.60%)>RT (0.6%) in terms of improvement rate. In addition, the safety of the 6 CPMs did not significantly differ in terms of adverse effects. The SUCRA values indicated that QT performed slightly worse than other drugs.

DISCUSSION

In treating vitiligo, QT is most effective but only suitable for short-term administration owing to its poor safety. VCP and QP could be used as first-choice long-term medications. TP may positively affect repigmentation in patients with limited lesion areas.

Crystal structures of human muscle fructose-1,6-bisphosphatase: novel quaternary states, enhanced AMP affinity, and allosteric signal transmission pathway

Fructose-1,6-bisphosphatase, a key enzyme in gluconeogenesis, is subject to metabolic regulation. The human muscle isozyme is significantly more sensitive towards the allosteric inhibitor, AMP, than the liver isoform. Here we report crystal structures and kinetic studies for wild-type human muscle Fru-1,6-Pase, the AMP-bound (1.6 Å), and product-bound complexes of the Q32R mutant, which was firstly introduced by an error in the cloning. Our high-resolution structure reveals for the first time that the higher sensitivity of the muscle isozyme towards AMP originates from an additional water-mediated, H-bonded network established between AMP and the binding pocket. Also present in our structures are a metaphosphate molecule, alternate conformations of Glu97 coordinating Mg²⁺, and possible metal migration during catalysis. Although the individual subunit is similar to previously reported Fru-1,6-Pase structures, the tetrameric assembly of all these structures deviates from the canonical R- or T-states, representing novel tetrameric assemblies. Intriguingly, the concentration of AMP required for 50% inhibition of the Q32R mutant is increased 19-fold, and the cooperativity of both AMP and Mg²⁺ is abolished or decreased. These structures demonstrate the Q32R mutation affects the conformations of both N-terminal residues and the dynamic loop 52–72. Also importantly, structural comparison indicates that this mutation in helix α2 is detrimental to the R-to-T conversion as evidenced by the absence of quaternary structural changes upon AMP binding, providing direct evidence for the critical role of helix α2 in the allosteric signal transduction.

Fructose-1,6-bisphosphatase genes in animals

A comparison of the amino acid sequences of the liver and muscle fructose-1,6-bisphosphatase (FbPase) isoforms in primates and rodents suggested an ancient duplication event leading to the corresponding genes. We investigated the presence of both genes in the rabbit (order lagomorphs) and in species belonging to further distantly related metazoan taxa. By an analysis of the available complete genomes and proteomes of the nematode Caenorhabditis elegans and of Drosophila melanogaster only one sequence homologous to known FbPases was found in each species. The corresponding mRNAs were characterized by cDNA sequencing. We then carried out reverse transcription-polymerase chain reactions to amplify central fragments of the FbPase cDNAs from liver and muscle of Gallus gallus, Xenopus laevis, and Esox lucius, respectively. Their sequencing revealed that (i) the livers of chicken, frog, and fish contain mRNAs which are closely related to mammalian liver FbPase mRNAs, (ii) chicken muscle contains an mRNA which is most homologous to mammalian muscle FbPase mRNAs, (iii) frog muscle contains both a liver-type and a muscle-type FbPase mRNA, while (iv) in fish muscle no FbPase mRNA could be detected by our approach despite the doubtless presence of the enzyme in this organ. An alignment of the partial amino acid sequences of the different FbPases showed that the residues that are thought to be in contact with the substrate, fructose-2,6-bisphosphate, and Mg(2+) are totally conserved, while some amino acids having contact with adenosine monophosphate were found to vary among several species. The question of what might be the advantage of having more than one gene coding for FbPase per haploid genome is discussed.

Association and activation of fructose 1,6-bisphosphase during unfolding and refolding: spectroscopic and enzymatic studies

Fructose 1,6-biphosphase is a well-characterized oligomer enzyme, and many effectors allosterically control its activity. In this report, we compared the activity, allosteric properties, and conformational changes in its denaturant-induced unfolding processes. In addition, a trpytophan residue has been introduced into the interface between the C1 and C2 subunits to investigate conformational changes during unfolding. Results show that the denaturation curves of WT FruP2ase detected by various methods do not agree, and the dissociation occurs first with a monomeric form existing around 0.4 M GdmCl as shown by gel filtration. The dissociation of all mutants is accompanied by changes in fluorescence intensity. The results suggest that the unfolding of FruP2ase is a complicated, multiphase process. The activation of FruP2ase by GdmCl at low concentrations can be interpreted as a consequence of the effect of monovalent cation. In the refolding experiments, it is found that Mg2+ is not only essential for enzyme activity, but also can assist the enzyme in refolding and association by preventing the formation of aggregates.