Mechanism of DNA cleavage by the endonuclease SauUSI: a major barrier to horizontal gene transfer and antibiotic resistance in Staphylococcus aureus.

Acquisition of foreign DNA by Staphylococcus aureus, including vancomycin resistance genes, is thwarted by the ATP-dependent endonuclease SauUSI. Deciphering the mechanism of action of SauUSI could unravel the reason how it singularly plays a major role in preventing horizontal gene transfer (HGT) in S. aureus.

Diguanylate Cyclases in : Essential Regulators of Lifestyle Switching.

Biofilm formation in empowers the bacteria to lead a dual lifestyle and enhances its infectivity. While the formation and dispersal of the biofilm involves multiple components-both proteinaceous and non-proteinaceous, the key to the regulatory control lies with the ubiquitous secondary signaling molecule, cyclic-di-GMP (c-di-GMP). A number of different cellular components may interact with c-di-GMP, but the onus of synthesis of this molecule lies with a class of enzymes known as diguanylate cyclases (DGCs).

The conserved aspartate in motif III of b family AdoMet-dependent DNA methyltransferase is important for methylation.

S-adenosyl-L-methionine (AdoMet)-dependent methyltransferases (MTases) are involved in diverse cellular functions. These enzymes show little sequence conservation but have a conserved structural fold. The DNA MTases have characteristic motifs that are involved in AdoMet binding, DNA target recognition and catalysis.

Structure of the active GGEEF domain of a diguanylate cyclase from Vibrio cholerae.

Cyclic-di-GMP (c-di-GMP) synthesized by diguanylate cyclases has been an important and ubiquitous secondary messenger in almost all bacterial systems. In Vibrio cholerae, c-di-GMP plays an intricate role in the production of the exopolysaccharide matrix, and thereby, in biofilm formation. The formation of the surface biofilm enables the bacteria to survive in aquatic bodies, when not infecting a human host.

DNA binding, cleavage and cytotoxicity studies of three mononuclear Cu(II) chloro-complexes containing N-S donor Schiff base ligands.

We report the biological activity of three Cu(II) complexes [Cu(pabt)Cl] (1), [Cu(pma)Cl] (2), and [Cu(pdta)Cl]Cl (3) (pabt = N-(2-mercaptophenyl)-2'-pyridylmethylenimine, pma = N-(2-pyridylmethyl)-2-mercaptoaniline, pdta = 2,2'-di(pyridyl-2-methyleneimine)diphenyl disulfide). 1-3 display four-line EPR multiplet in solution at RT suggesting that these are mononuclear. DNA-binding studies using spectrophotometric titration of these complexes with calf thymus DNA showed binding through intercalation mode which was found to be consistent with the observation of increased viscosity of DNA and quenching of fluorescence of ethidium bromide bound DNA in the presence of these complexes.

Subtle Changes Due to Mutations in the GGDEF Domain Result in Loss of Biofilm Forming Activity in the VC0395_0300 Protein from Vibrio cholerae, but No Major Change in the Overall Structure.

Background: Cyclic-di-GMP (c-di-GMP) is a ubiquitous secondary messenger molecule in bacteria synthesized by diguanylate cyclases. This universal messenger regulates diverse cellular functions in bacteria at the transcriptional, translational and posttranslational levels. The cellular functions regulated by c-di-GMP include cell motility, cell cycle progression, virulence, biofilm formation, antibiotic production and other unknown functions.

Putative protein VC0395_0300 from Vibrio cholerae is a diguanylate cyclase with a role in biofilm formation.

The hallmark of the lifecycle of Vibrio cholerae is its ability to switch between two lifestyles - the sessile, non-pathogenic form and the motile, infectious form in human hosts. One of these changes is in the formation of surface biofilms, when in sessile aquatic habitats. The cell-cell interactions within a V.

Effect of site-directed mutagenesis at the GGEEF domain of the biofilm forming GGEEF protein from Vibrio cholerae.

Vibrio cholerae, the cause of seven noted pandemics, leads a dual lifecycle-one in the human host in its virulent form, and the other as a sessile, non-virulent bacterium in aquatic bodies in surface biofilms. Surface biofilms have been attributed to be associated with a ubiquitous protein domain present in all branches of bacteria, known as the GGD(/E)EF domain. While the diguanlyate cyclase activities of these proteins are universally established, the role of these proteins as diguanlyate-specific phosphodiesterases in conjunction with a EAL domain has also been reported.