Purification of GidA protein, a novel topoisomerase II inhibitor produced by Streptomyces flavoviridis

Pharmacological assessment of Ru(II) complex with GidA protein- A novel topoisomerase II inhibitor towards cancer therapeutics

The interactions of ruthenium(II) complex with Glucose inhibited division protein A (GidA protein) was studied through various spectroscopic techniques with the ultimate goal of preparing adducts with good selectivity for cancer cells. In all the cases, formation of a tight metal-protein conjugate was observed. The influence of pH, reducing agents and chelators on the formation of adduct was analysed by UV- visible spectroscopy. While there was no effect on the addition of sodium ascorbate, some alterations on some selected bands were seen on the UV-visible spectra on the addition of EDTA. The adduct was stable in the pH range of 5-8. Addition of ruthenium(II) complex effectively quenched the intrinsic fluorescence of GidA and it occurred through static quenching. The effect of ruthenium(II) complex on the conformation of GidA has been examined by analyzing CD spectrum. Though, there was some conformational changes observed in the presence of ruthenium(II) complex, α- helix in the secondary structure of GidA retained its identity. Molecular docking of ruthenium(II) complex with GidA also indicated that GidA docks through hydrophobic interaction. The stable semisynthetic complex (ruthenium(II) complex with GidA) was checked for topoisomerase II inhibition. Relaxation and decatenation assay proved topoisomerase II inhibition of semisynthetic complex.Communicated by Ramaswamy H. Sarma.

RNA modification enzymes encoded by the gid operon: Implications in biology and virulence of bacteria

Ribonucleic acid (RNA) molecules consist of numerous chemically modified nucleosides that are highly conserved in eukarya, archeae, and bacteria, while others are unique to each domain of life. In bacteria, hundreds of RNA modification enzymes have been identified and implicated in biological pathways associated with many cell processes. The glucose-inhibited division (gid) operon encodes genes for two RNA modification enzymes named GidA and GidB. Studies have shown GidA is essential for the proper biosynthesis of 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U) of bacterial transfer RNA (tRNA) with GidB responsible for the methylation of the 16S ribosomal RNA (rRNA). Furthermore, deletion of gidA and gidB has shown to alter numerous bacterial properties like virulence, stress response, morphology, growth, antibiotic susceptibility, and others. In this review, we discuss the present knowledge of the RNA modification enzymes GidA and GidB, and their potential role in the biology and virulence of bacteria.