Targeting Streptococcus pneumoniae UDP-glucose pyrophosphorylase (UGPase): in vitro validation of a putative inhibitor

Heterologous expression and biological characteristics of UGPases from Lactobacillus acidophilus

Herein, two genes (LBA0625 and LBA1719) encoding UGPases (UDP-glucose pyrophosphorylase) in Lactobacillus acidophilus (L. acidophilus) were successfully transformed into Escherichia coli BL21 (DE3) to construct recombinant overexpressing strains (E-0625, E-1719) to investigate the biological characteristics of UGPase-0625 and UGPase-1719. The active sites, polysaccharide yield, and anti-freeze-drying stress of L. acidophilus ATCC4356 were also detected. UGPase-0625 and UGPase-1719 belong to the nucleotidyltransferase of stable hydrophilic proteins; contain 300 and 294 amino acids, respectively; and have 20 conserved active sites by prediction. Αlpha-helixes and random coils were the main secondary structures, which constituted the main skeleton of UGPases. The optimal mixture for the high catalytic activity of the two UGPases included 0.5 mM UDP-Glu (uridine diphosphate glucose) and Mg²⁺ at 37 °C, pH 10.0. By comparing the UGPase activities of the mutant strains with the original recombinant strains, A10, L130, and L263 were determined as the active sites of UGPase-0625 (P < 0.01) and A11, L130, and L263 were determined as the active sites of UGPase-1719 (P < 0.01). In addition, UGPase overexpression could increase the production of polysaccharides and the survival rates of recombinant bacteria after freeze-drying. This is the first study to determine the enzymatic properties, active sites, and structural simulation of UGPases from L. acidophilus, providing in-depth understanding of the biological characteristics of UGPases in lactic acid bacteria.Key points• We detected the biological characteristics of UGPases encoded by LBA0625 and LBA1719.• We identified UGPase-0625 and UGPase-1719 active sites.• UGPase overexpression elevates polysaccharide levels and post-freeze-drying survival.

Antimicrobial Susceptibility Pattern and Serotype Distribution of Streptococcus pneumoniae Isolates From a Hospital-Based Study in Chandigarh, North India

Streptococcus pneumoniae (pneumococcus) causes significant infection-related morbidity and mortality worldwide. The genome plasticity of pneumococcus is an essential factor in antibiotic resistance, serotype switching, and the emergence of nonvaccine serotypes. Information regarding the serotype distribution as well as antimicrobial susceptibility in pneumococcus clinical isolates responsible for various infections in Northern India is limited. Here, we have explored the antibiotic resistance and serotype pattern associated with S. pneumoniae infections from both invasive and noninvasive sites of patients of all ages, visiting out-patient department of a tertiary care hospital (PGIMER, Chandigarh, India). This study was carried out on 68 S. pneumoniae isolates and the isolates exhibited the highest resistance (76.5%) to cotrimaxozole followed by resistance toward tetracycline (36.8%) and erythromycin (23.5%). All isolates showed vancomycin susceptibility and 86.8% of isolates showed sensitivity to chloramphenicol. Multidrug resistance was found in 32% (n=22) of the S. pneumoniae isolates showing resistance toward three different antibiotics. Serotype 19F was found to be the most prevalent serotype (39%) followed by serotypes 6A/B/C (19%) and 1 (12%). These data shed light on the latest trends in antibiotic susceptibility and prevalent serotype patterns of hospital-based S. pneumoniae isolates. This information can be helpful in designing future disease-preventive strategies.

In Vitro Models for Studying Respiratory Host-Pathogen Interactions

Respiratory diseases and lower respiratory tract infections are among the leading cause of death worldwide and, especially given the recent severe acute respiratory syndrome coronavirus-2 pandemic, are of high and prevalent socio-economic importance. In vitro models, which accurately represent the lung microenvironment, are of increasing significance given the ethical concerns around animal work and the lack of translation to human disease, as well as the lengthy time to market and the attrition rates associated with clinical trials. This review gives an overview of the biological and immunological components involved in regulating the respiratory epithelium system in health, disease, and infection. The evolution from 2D to 3D cell biology and to more advanced technological integrated models for studying respiratory host-pathogen interactions are reviewed and provide a reference point for understanding the in vitro modeling requirements. Finally, the current limitations and future perspectives for advancing this field are presented.