A protocol for cloning, expression, and purification of Lysine exporter (LysE) gene of Mycobacterium tuberculosis

Background

Tuberculosis (TB) is among the deadliest diseases and a significant cause of illnessacross the globe. Several studies on mycobacterial proteins, such as proteases and transporters that are essential for survival and pathogenesis have aimed to develop an efficient anti-tubercular agent. In mycobacterium, lysine exporter (LysE) is an amino acid transporter and a probable target for an anti-tubercular agent as it is responsible for bacterial growth inhibition and is also absent in the widely used Bacillus Calmette-Guérin (BCG) vaccine.

Methods

Some studies have purified LysE using different protocols. This study describes a protocol for purifying different constructs of LysE, focusing on its hydrophobic region using immobilized metal affinity chromatography (IMAC) after expressing LysE gene in a bacterial expression system. pET vector (pET28a) is used as an expression vector. Amplified LysE gene is ligated with the pET28a vector, and the resultant plasmid is then transformed into E. coli cells. The vector has a histidine tag that makes the purification process convenient. After IMAC, the samples will be subjected to size-exclusion chromatography for further purification.

Results

Cloning and amplification findings will be analyzed using 1% agarose gel, and protein expression and purification outcomes will be examined using sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Domain-specific constructs of LysE can be further analyzed as an anti-tubercular agent.

Conclusions

Despite being a potential anti-tubercular target, research is quite limited on this protein. Therefore, we aim to purify LysE protein for further analysis. Similar protocols have already been implemented to purify several other bacterial proteins with >95% purity.

The susceptibility of anti-tuberculosis drug-induced liver injury and chronic hepatitis C infection: A systematic review and meta-analysis

BACKGROUND

Anti-tuberculosis drug-induced liver injury (ATDILI) is a major safety concern in the treatment of tuberculosis (TB). The impact of chronic hepatitis C (CHC) infection on the risk of ATDILI is still controversial. We aimed to assess the influence of CHC infection on ATDILI through a systematic review and meta-analysis.

METHODS

We systemically reviewed all English-language literature in the major medical databases with the subject search terms "anti-tuberculosis drug-induced liver injury" and "anti-tuberculosis drug-induced hepatotoxicity". We then performed a systematic review and meta-analysis of the papers relevant to hepatitis C in qualified publications.

RESULTS

A total of 14 studies were eligible for analysis, which included 516 cases with ATDILI and 4301 controls without ATDILI. The pooled odds ratio (OR) of all studies for CHC infection to ATDILI was 3.21 (95% confidence interval (CI): 2.30-4.49). Subgroup analysis revealed that the CHC carriers had a higher risk of ATDILI than those without CHC both in Asians (OR = 2.96, 95% CI: 1.79-4.90) and Caucasians (OR = 4.07, 95% CI: 2.70-6.14), in those receiving standard four combination anti-TB therapy (OR = 2.94, 95% CI: 1.95-4.41) and isoniazid monotherapy (OR = 4.18, 95% CI: 2.36-7.40), in those with a strict definition of DILI (serum alanine aminotransferase [ALT] > 5 upper limit of normal value [ULN], OR = 2.59, 95% CI: 1.58-4.25) and a loose definition of DILI (ALT > 2 or 3 ULN, OR = 4.34, 95% CI: 2.96-6.37), and in prospective studies (OR = 4.16, 95% CI: 2.93-5.90) and case-control studies (OR = 2.43, 95% CI: 1.29-4.58).

CONCLUSION

This meta-analysis suggests that CHC infection may increase the risk of ATDILI. Regular liver tests are mandatory for CHC carriers under anti-TB therapy.

Discovery of new chemical entities as potential leads against Mycobacterium tuberculosis

A series of biheterocyclic (1H-indole, benzofuran, pyrazolo[1,5-a]pyrimidine, pyrazolo[1,5-a]pyrimidin-5(4H)-one, imidazo[2,1-b]thiazole and pyrazolo[5,1-b]thiazole) derivatives were synthesized and evaluated for their anti-tubercular activities. The imidazo[2,1-b]thiazoles 9a-c and pyrazolo[5,1-b]thiazoles 10a-c exhibited promising anti-tubercular activity in varying degrees. Especially, the 2,6-dimethylpyrazolo[5,1-b]thiazole 10a exhibited strong suppressing function against H37Ra strain with MIC value of 0.03μg/mL. Compound 10a also displayed good pharmacokinetic profiles with oral bioavailability (F) of 41.7% and a half-life of 13.4h. Furthermore, 10a significantly reduced the bacterial burden in an autoluminescent H37Ra infected mouse model, suggesting its promising potential for development of anti-tubercular drugs.

Synthesis of novel 4-nitropyrrole-based semicarbazide and thiosemicarbazide hybrids with antimicrobial and anti-tubercular activity

We report the synthesis and screening of forty novel 4-nitropyrrole-semicarbazide conjugates inspired from the reported bio-potential of bromopyrrole alkaloids and semicarbazide derivatives for antimicrobial activity. Herein, hybrids 5k-5o, 5r, 5s and 5t displayed four-fold increased activity (MIC=0.39 μg/mL) against Escherichia coli compared to standard ciprofloxacin. Eight hybrids, 5k-5o and 5r-5t displayed equal antibacterial activity (MIC=1.56 μg/mL) against Klebsiella pneumonia compared to standard ciprofloxacin. Hybrid, 5k-5o (MIC=0.195 μg/mL) displayed highly potent antibacterial activity against MSSA as compared to standard ciprofloxacin. Eight-fold superior activity was observed for four hybrids 5k-5m and 5o (MIC=0.39 μg/mL) against MRSA. Further, nine hybrids displayed four-fold superior antifungal activity (MIC=0.78 μg/mL) compared to standard Amphotericin B. Encouraging MICs of these hybrids recognize them as promising leads for development of potential antimicrobial drugs.

Synthesis and evaluation of novel 4-nitropyrrole-based 1,3,4-oxadiazole derivatives as antimicrobial and anti-tubercular agents

We report synthesis and antimicrobial evaluation of 42 novel 4-nitropyrrole-based 1,3,4-oxadiazoles. The synthesized molecules were evaluated for anti-bacterial, anti-fungal and anti-tubercular activities. Promisingly, most of the compounds showed equal or more potency than standard ciprofloxacin against Staphylococcus aureus, Bacillus subtilis and Escherichia coli. Compound 5e exhibited highest anti-tubercular activity (0.46 μg/mL) close to that of standard Isoniazid (0.40 μg/mL). Equal antifungal activity (1.56 μg/mL) compared to standard Amphotericin-B was shown by most of the compounds. All the N-methylated compounds showed more potent to equal activity against MSSA (MIC 0.39-1.56 μg/mL) and MRSA (MIC 0.78-1.56 μg/mL). All compounds were tested for mammalian cell toxicity using VERO cell line and were found to be non-toxic.