Humans ; Staphylococcus lugdunensis/genetics* ; Peptides, Cyclic ; Chromosomes ; Operon/genetics* ; Staphylococcal Infections/genetics* ; Bacterial Proteins/genetics* ; Anti-Bacterial Agents

To investigate the effect and the mechanism of ppk1 gene deletion on the drug susceptibility of uropathogenic Escherichia coli producing extended-spectrum beta-lactamases (ESBLs-UPEC). The study was an experimental study. From March to April 2021, a strain of ESBLs-UPEC (genotype was TEM combined with CTX-M-14) named as UE210113, was isolated from urine sample of the patient with urinary tract infection in the Laboratory Department of Guangzhou Eighth People's Hospital, meanwhile its ppk1 gene knock-out strain Δpk1 and complemented strain Δpk1-C were constructed by suicide plasmid homologous recombination technique, which was used to study the effect of ppk1 gene on ESBLs-UPEC drug sensitivity and its mechanism. The drug susceptibility of UE210113, Δpk1, and Δpk1-C were measured by Vitek2 Compact System and broth microdilution method. The quantitative expression of ESBLs, outer membrane protein and multidrug efflux systems encoding genes of UE210113, Δpk1 and Δpk1-C were performed by using qRT-PCR analysis. By using two independent sample Mann-Whitney U test, the drug susceptibility results showed that, compared with UE210113 strain, the sensitivities of Δpk1 to ceftazidime, cefepime, tobramycin, minocycline and cotrimoxazole were enhanced (Z=-2.121,P<0.05;Z=-2.236,P<0.05;Z=-2.236,P<0.05;Z=-2.121,P<0.05), and the drug susceptibility of Δpk1-C restored to the same as which of UE210113 (Z=0,P>0.05). The expression levels of ESBLs-enconding genes bla_TEM and bla_CTX-M-14 in Δpk1 were significantly down-regulated compared with UE210113, but the expression was not restored in Δpk1-C. The expression of outer membrane protein gene omp F in Δpk1 was significantly up-regulated, while the expression of omp A and omp C were down-regulated. The results showed that the expression of multidrug efflux systems encoding genes tol C, mdt A and mdtG were down-regulated in Δpk1 compared with UE210113. The expression of all of the outer membrane protein genes and the multidrug efflux systems genes were restored in Δpk1-C. In conclusion,the lost of ppk1 gene can affect the expression of the outer membrane protein and multidrug efflux systems encoding genes of ESBLs-UPEC, which increase the sensitivity of ESBLs-UPEC to various drugs.
Humans ; beta-Lactamases/metabolism* ; Uropathogenic Escherichia coli/metabolism* ; Urinary Tract Infections ; Plasmids ; Membrane Proteins/genetics* ; Escherichia coli Infections ; Microbial Sensitivity Tests ; Anti-Bacterial Agents/pharmacology*

Heme/metabolism* ; Cryoelectron Microscopy ; Membrane Transport Proteins ; Escherichia coli Proteins/metabolism*

Humans ; Botulinum Toxins, Type A/therapeutic use* ; Esotropia/drug therapy* ; Neuromuscular Agents ; Injections ; Treatment Outcome ; Oculomotor Muscles

Humans ; Isoniazid/pharmacology* ; Mycobacterium tuberculosis/genetics* ; Rifampin/pharmacology* ; Antitubercular Agents/pharmacology* ; Mutation ; Microbial Sensitivity Tests ; Tuberculosis, Multidrug-Resistant/microbiology* ; Drug Resistance, Multiple, Bacterial/genetics* ; Bacterial Proteins/genetics*

OBJECTIVE: This study aimed to investigate whether the VCA0560 gene acts as an active diguanylate cyclase (DGC) in Vibrio cholerae and how its transcription is regulated by Fur and HapR. METHODS: The roles of VCA0560 was investigated by utilizing various phenotypic assays, including colony morphological characterization, crystal violet staining, Cyclic di-GMP (c-di-GMP) quantification, and swimming motility assay. The regulation of the VCA0560 gene by Fur and HapR was analyzed by luminescence assay, electrophoretic mobility shift assay, and DNase I footprinting. RESULTS: VCA0560 gene mutation did not affect biofilm formation, motility, and c-di-GMP synthesis in V. cholerae, and its overexpression remarkably enhanced biofilm formation and intracellular c-di-GMP level but reduced motility capacity. The transcription of the VCA0560 gene was directly repressed by Fur and the master quorum sensing regulator HapR. CONCLUSION Overexpressed VCA0560 functions as an active DGC in V. cholerae, and its transcription is repressed by Fur and HapR.
Vibrio cholerae/genetics* ; Biofilms ; Quorum Sensing ; Mutation ; Gene Expression Regulation, Bacterial ; Bacterial Proteins/genetics*

L-methionine, also known as L-aminomethane, is one of the eight essential amino acids required by the human body and has important applications in the fields of feed, medicine, and food. In this study, an L-methionine high-yielding strain was constructed using a modular metabolic engineering strategy based on the M2 strain (Escherichia coli W3110 ΔIJAHFEBC/PAM) previously constructed in our laboratory. Firstly, the production of one-carbon module methyl donors was enhanced by overexpression of methylenetetrahydrofolate reductase (methylenetetrahydrofolate reductase, MetF) and screening of hydroxymethyltransferase (GlyA) from different sources, optimizing the one-carbon module. Subsequently, cysteamine lyase (hydroxymethyltransferase, MalY) and cysteine internal transporter gene (fliY) were overexpressed to improve the supply of L-homocysteine and L-cysteine, two precursors of the one-carbon module. The production of L-methionine in shake flask fermentation was increased from 2.8 g/L to 4.05 g/L, and up to 18.26 g/L in a 5 L fermenter. The results indicate that the one carbon module has a significant impact on the biosynthesis of L-methionine, and efficient biosynthesis of L-methionine can be achieved through optimizing the one carbon module. This study may facilitate further improvement of microbial fermentation production of L-methionine.
Humans ; Methionine ; Methylenetetrahydrofolate Reductase (NADPH2) ; Carbon ; Cysteine ; Escherichia coli/genetics* ; Hydroxymethyl and Formyl Transferases ; Carrier Proteins ; Escherichia coli Proteins

The aim of this study was to prepare tandem multimeric proteins of BmSPI38, a silkworm protease inhibitor, with better structural homogeneity, higher activity and stronger antifungal ability by protein engineering. The tandem multimeric proteins of BmSPI38 were prepared by prokaryotic expression technology. The effects of tandem multimerization on the structural homogeneity, inhibitory activity and antifungal ability of BmSPI38 were explored by in-gel activity staining of protease inhibitor, protease inhibition assays and fungal growth inhibition experiments. Activity staining showed that the tandem expression based on the peptide flexible linker greatly improved the structural homogeneity of BmSPI38 protein. Protease inhibition experiments showed that the tandem trimerization and tetramerization based on the linker improved the inhibitory ability of BmSPI38 to microbial proteases. Conidial germination assays showed that His₆-SPI38L-tetramer had stronger inhibition on conidial germination of Beauveria bassiana than that of His₆-SPI38-monomer. Fungal growth inhibition assay showed that the inhibitory ability of BmSPI38 against Saccharomyces cerevisiae and Candida albicans could be enhanced by tandem multimerization. The present study successfully achieved the heterologous active expression of the silkworm protease inhibitor BmSPI38 in Escherichia coli, and confirmed that the structural homogeneity and antifungal ability of BmSPI38 could be enhanced by tandem multimerization. This study provides important theoretical basis and new strategies for cultivating antifungal transgenic silkworm. Moreover, it may promote the exogenous production of BmSPI38 and its application in the medical field.
Animals ; Antifungal Agents/pharmacology* ; Escherichia coli/metabolism* ; Proteins/metabolism* ; Protease Inhibitors/chemistry* ; Bombyx/chemistry* ; Saccharomyces cerevisiae/metabolism* ; Peptide Hydrolases

As an important protein structure on the surface of bacteria, type Ⅳ pili (TFP) is the sensing and moving organ of bacteria. It plays a variety of roles in bacterial physiology, cell adhesion, host cell invasion, DNA uptake, protein secretion, biofilm formation, cell movement and electron transmission. With the rapid development of research methods, technical equipment and pili visualization tools, increasing number of studies have revealed various functions of pili in cellular activities, which greatly facilitated the microbial single cell research. This review focuses on the pili visualization method and its application in the functional research of TFP, providing ideas for the research and application of TFP in biology, medicine and ecology.
Fimbriae, Bacterial/metabolism* ; Bacterial Proteins/genetics* ; Bacterial Physiological Phenomena ; Bacterial Adhesion/physiology*

D-mannose has many functional activities and is widely used in food, medicine, agriculture and other industries. D-mannitol oxidase that can efficiently convert D-mannitol into D-mannose has potential application in the enzymatic preparation of D-mannose. A D-mannitol oxidase (PsOX) was found from Paenibacillus sp. HGF5. The similarity between PsOX and the D-mannitol oxidase (AldO) from Streptomyces coelicolor was 50.94%. The molecular weight of PsOX was about 47.4 kDa. A recombinant expression plasmid pET-28a-PsOX was constructed and expressed in Escherichia coli BL21(DE3). The K_m and k_cat/K_m values of PsOX for D-mannitol were 5.6 mmol/L and 0.68 L/(s·mmol). Further characterization of PsOX showed its optimal pH and temperature were 7.0 and 35 ℃, respectively, while its enzyme activity could be stably remained below 60 ℃. The molar conversion rate of 400 mmol/L D-mannitol by PsOX was 95.2%. The whole cells of PsOX and AldO were used to catalyze 73 g/L D-mannitol respectively. The reaction catalyzed by PsOX completed in 9 h and 70 g/L D-mannose was produced. PsOX showed a higher catalytic efficiency compared to that of AldO. PsOX may facilitate the enzymatic preparation of D-mannose as a novel D-mannose oxidase.
Recombinant Proteins/metabolism* ; Paenibacillus/metabolism* ; Mannose/metabolism* ; Escherichia coli/metabolism* ; Mannitol/metabolism*