Patatin-like phospholipases (PLPs) are important virulence factors of many pathogens. However, there are no prevailing studies regarding PLPs as a virulence factor of Mycobacterium tuberculosis (Mtb). Analysis of Rv3091, a putative protein of Mtb, shows that it belongs to the PLPs family. Here, we cloned and expressed the rv3091 gene in Mycobacterium smegmatis and, subsequently, conducted protein purification and characterization. We show that it possesses phospholipase A 1 , phospholipase A 2 , and lipase activity. We confirm the putative active site residues, namely, Ser214 and Asp407, using site directed mutagenesis. The Rv3091 is an extracellular protein that alters the colony morphology of M. smegmatis. The presence of Rv3091 enhances the intracellular survival capability of M. smegmatis in murine peritoneal macrophages. Additionally, it promotes M. smegmatis phagosomal escape from macrophages. Moreover, Rv3091 significantly increased the survival of M. smegmatis and aggravated lesions in C57BL/6 J murine lungs in vivo. Taken together, our results indicate that Rv3091 as an extracellular PLP that is critical to the pathogenicity of mycobacterium as it allows mycobacterium to utilize phospholipids for its growth and provides resistance to phagosome killing, resulting in its enhanced intracellular survival.

Some new 4H-pyrrolo[1,2-a]benzimidazoles(2a-2f) have been synthesized. The structures of these compounds were confirmed by IR, 1 H NMR, mass spectroscopy and elemental analysis. Compound 2a was further confirmed by X-ray diffraction. The in vitro antimicrobial activities of these compounds were determined against some gram-positive bacteria, gram-negative bacteria and fungi and their drug-resistant isolates in comparison with standard drugs. Antimicrobial results indicate that compounds 2c, 2d and 2e show moderately active antibacterial properties, their minimum inhibitory concentrations are from 12.5 μg/mL to 125 μg/mL. In the series, the most active compound against C. albicans is compound 2f with an MIC value of 31.25 μg/mL.

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