LtnA1

PDFOZ D-5Y W-17L C1S M4I D1 A N14I W18C L21F A27V A-9V A4S SSV N18K pMRCOI F- L E-14G Q-21L S2N SSC Wt2C GtSE T20I A27T W28R D-14L S16R T2SI Fig. 2. a Bioactivity results of lacticin 3147 mutants as determined by well-diffusion assays. b Lacticin 3147 mutants created by random mutagenesis. Black circles indicate the mutations made within the LtnAl and LtnA2 peptides as well as the leader regions. Posttranslational modifications are indicated in grey. Dhb Dehydrobu-tyrine, Abu 2-aminobutyric...

Introduction

The emergence of antibiotic resistance, such as vanco-mycin-resistant enterococci and methicillin-resistant staphylococci, has been of great concern in recent years, so there is a pressing need for development of novel antimicrobial agents. Among many candidates, interest in working with antimicrobial peptides is being inspired by the possibility of using them as alternative antibiotics. Lantibiotics are ribosomally synthesized post-transla-tionally modified antimicrobial peptides that contain...

Target Cell Membranes

The a- and p-peptides of enterocin 1071 and lactococcin G and Q have putative amphiphilic a-helices in their N-terminal and mid region (residues 3-27 in a and 8-25 in p) as judged by displaying their sequences on an Ed-mundson a-helical wheel 6, 8, 9 . The non-polar amino acids are found almost exclusively on one side of the helix while the polar residues are found on the opposite side. CD structural studies of the lactococcin G a- and p-peptides and fragments thereof show that the a- and...

Mechanisms of Action

Hydroxamate Complex

The great differences between eukaryotic and pro-karyotic AMPs concern the antibiotic efficacy and the microbial target specificity. The AMPs secreted by bacteria (bacteriocins and microcins) appear to be overall more potent than those from Eukaryota, since they are active in the pico- to nanomolar concentration range, while the latter are active at micromolar concentrations. In addition, they have a narrow spectrum of activity, susceptible strains being essentially closely related to the...

Promising Applications

Although bacteriocins may be found in many Grampositive and Gram-negative bacteria 12 , those produced by LAB have received particular attention in recent years due to their potential application in the food industry as natural preservatives 13 . Bacteriocins produced by LAB are small, ribosomally synthesized, antimicrobial pep-tides or proteins that possess activity towards closely related Gram-positive bacteria, whereas producer cells are immune to their own bacteriocin(s) 5, 11, 14 . The...

References

1 Nes IF, Diep DB, Havarstein LS, Brurberg 8 MB, Eijsink V, Holo H Biosynthesis of bacteriocins in lactic acid bacteria. Antonie van Leeuwenhoek 1996 70 113-128. 2 Nissen-Meyer J, Nes IF Ribosomally synthe sized antimicrobial peptides their function, structure, biogenesis, and mechanism of action. Arch Microbiol 1997 167 67-77. 9 3 Nes IF, Holo H, Fimland G, Hauge HH, Nissen-Meyer J Unmodified peptide-bacterio-cins (class II) produced by lactic acid bacteria in Dutton CJ, Haxell MA, McArthur...

Localization and Interaction of the Biosynthetic Enzymes for Nukacin ISK1

Knowledge on the nukacin ISK-1 biosynthetic enzymes would thus be important for understanding the properties as well as the possibility of their application for lantibiotic engineering. We therefore characterized biophysical and biochemical aspects of the nukacin ISK-1 biosynthetic enzymes. Localization analysis of NukM and NukT in the wildtype strain by Western blotting indicated that both proteins were located at the cytoplasmic membrane. NukM expressed heterologously in Staphylococcus...

Experimental Procedures

Bacterial Strains and Growth Conditions L. lactis MG1614 pNZ9111 33 was used as the source of nisABC genes. L. lactis LAC240 34 was used as the indicator strain in nisin detection by nisin-inducible GFP fluorescence. Lactococci were grown at 30 C in M17 medium Oxoid containing 0.5 w v glucose and 5 g ml erythromycin. M. luteus A1 NCIMB86166 National Collection of Industrial and Marine Bacteria was used as the indicator bacteria in agar diffusion bioassay of nisin. M. luteus was cultivated in LB...

Discussion

In this study, fully modified nisin precursor was produced in the in vitro RTS by using gene expression templates nisA, nisB, and nisC. Antimicrobially active nisin was obtained from the RTS mixture by trypsin treatment. The results revealed that all modifications of nisin precursor can take place in vitro without membrane association and the transporter protein NisT. First, we tested the RTS reaction mixture with Western analysis using nisin A-specific antibody. A protein of same size as...

Structural Diversity of Microcins

Among the eleven microcins identified until now, only six have been structurally characterized MccB17, MccC7 C51, MccE492, MccJ25, MccL and MccV also known as ColV, since initially described as a colicin , while the others MccD93, MccH47, MccI47, MccM, Mcc24 have been essentially studied through genetical approaches. MccB17 is a 43-residue peptide characterized by post-translational modifications consisting of thiazole and ox-azole rings 18 . MccC7 C51 is a short nucleotide hepta-peptide 19-21...

Abstract

Psec Vector

Divercin V41 is a class IIa bacteriocin produced by Carnobacterium divergens V41 with a strong anti-Listeria activity. We have previously produced a recombinant form of divercin V41 DvnRV41 in Escherichia coli strain Origami, by cloning a synthetic gene that codes for a mature divercin RV41 peptide. In this work we describe the inducible expression and secretion of DvnRV41 in the food-grade lactic acid bacterium, Lactococcus lactis. The production of DvnRV41 by recombinant L. lactis was...

Cluster for Nukacin ISK1

Lantibiotics are gene-encoded and, therefore, can be readily manipulated by genetic engineering, which provides an efficient means for constructing and producing large numbers of structural analogs needed for structure-function studies and rational design. So far, various expression and gene replacement strategies have been developed to produce engineered lantibiotics 13-16 . We demonstrated the heterologous expression and gene replacement system for nukacin ISK-1 biosynthetic gene cluster in...