There are many concerns about safety of food contaminated with antibacterial residues. This study was designed to investigate the occurrence of chloramphenicol (CAP) residue in broiler chickens tissues, namely liver, kidney and muscle. One hundred and sixty broiler chickens carcasses were collected from three provinces of Iran. Four Plate Test (FTP), ELISA and HPLC were used to qualify and quan...

Multidrug-resistant Staphylococcus aureus infections pose a significant threat to human health. Antibiotic resistance is most commonly propagated by conjugative plasmids like pLW1043, the first vancomycin-resistant S. aureus vector identified in humans. We present the molecular basis for resistance transmission by the nicking enzyme in S. aureus (NES), which is essential for conjugative transfe...

The gene cluster from Amycolotopsis orientalis responsible for biosynthesis of the vancomycin-type glycopeptide antibiotic chloroeremomycin was recently sequenced, indicating that this antibiotic derives from a seven-residue peptide synthesized by a three-subunit (CepA, CepB, and CepC) modular nonribosomal peptide synthetase. Expression of all or parts of the peptide synthetase in Escherichia c...

background: tetracyclines (tcs) are broad-spectrumantibiotics that are widely used in veterinary medicine. thepresence of tcs residues in milk is a public health concern allover the world. objectives:this study aimed to determine tcsresiduals in pasteurized milk marketed by some dairy companiesin tehran from april 2011 to march 2012. methods: 432pasteurized milk samples were purchased from supe...

The bld mutants of Streptomyces coelicolor A3(2) are blocked at the earliest stage of sporulation, the formation of aerial hyphae, and are pleiotropically defective in antibiotic production. Using a phage library of wild-type S. coelicolor DNA, we isolated a recombinant phage which restored both sporulation and antibiotic production to strains carrying the single known bldD mutation. Nucleotide...

UNLABELLED The antibiotic streptothricin (ST) possesses an amino sugar bound to an l-β-lysine (β-Lys) residue via a peptide bond. The peptide bond formation has been shown to be catalyzed by a nonribosomal peptide synthetase (NRPS) during ST biosynthesis. The focus of this study is the closely related ST analogue BD-12, which carries a glycine-derived side chain rather than a β-Lys residue. Her...

We have designed a 20-residue hybrid peptide CA(1-8)-MA(1-12) (CAMA) incorporating residues 1-8 of cecropin A (CA) and residues 1-12 of magainin 2 (MA) with high bacterial cell selectivity. CAMA-P2 is an αhelical antimicrobial peptide designed from a CAMA hybrid peptide and substitution of Gly-Ile-Gly hinge sequence of CAMA to Pro influences the flexibility at central part of CAMA. Based on str...

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Chloroeremomycin, a vancomycin family glycopeptide antibiotic has three sugars, one D-glucose and two L-4-epi-vancosamines, attached to the crosslinked heptapeptide backbone by three glycosyltransferases, GtfA, -B, and -C. Prior efforts have revealed that GtfB and -C in tandem build an epivancosaminyl-1,2-glucosyldisaccharide chain on residue 4 of the aglycone; however, the characterization of ...

PapC ushers are outer-membrane proteins enabling assembly and secretion of P pili in uropathogenic E. coli. Their translocation domain is a large -barrel occluded by a plug domain, which is displaced to allow the translocation of pilus subunits across the membrane. Previous studies suggested that this gating mechanism is controlled by a -hairpin and an -helix. To investigate the role of these e...