Colicins: structures, modes of action, transfer through membranes, and evolution (original) (raw)

Production of an E. coli toxin protein; Colicin A in E. coli using an inducible system

Turkish Journal of Chemistry, 2003

Colicins are bacterial toxins that kill Escherichia coli and related cells; their mode of action is of interest in protein import and toxicology. Colicins translocate across the E. coli outer membrane and periplasm by interacting with several receptors. This translocation process involves interaction of the colicin with the outer membrane porin OmpF and subsequently with the integral membrane protein TolA. The N-terminal domain of colicin N is involved in the import process. Our aim was to produce a large quantity of colicin A for functional and structural studies. It is a prerequisite to have a correctly folded and stable protein for these studies. The commonly utilised expression system uses the Lex A promoter, which requires induction with toxic mitomycin C, though the yield is low. Here we present the production of an E. coli toxin and its immunity protein in E. coli using a safe inducible promoter.

Crystal structure of a colicin N fragment suggests a model for toxicity

Structure, 1998

Background: Pore-forming colicins are water-soluble bacteriocins capable of binding to and translocating through the Escherichia coli cell envelope. They then undergo a transition to a transmembrane ion channel in the cytoplasmic membrane leading to bacterial death. Colicin N is the smallest pore-forming colicin known to date (40 kDa instead of the more usual 60 kDa) and the crystal structure of its membrane receptor, the porin OmpF, is already known. Structural knowledge of colicin N is therefore important for a molecular understanding of colicin toxicity and is relevant to toxic mechanisms in general.

Bacteriocins Nature, Function and Structure

Bacteriocins are extracellular substances produced by different types of bacteria, including both Gram positive and Gram negative species. They can be produced spontaneously or induced by certain chemicals such as mitomycin C. They arc biologically one of the important substances, and have been found to be useful in membrane studies and also in typing pathogenic microorganisms causing serious nosocomial infections. Bacteriocins are a heterogeneous group of particles with different morphological and biochemical entities. They range from a simple protein to a high molecular weight complex: the active moiety of each molecule in all cases seems to be protein in nature. The genetic determinants of most of the bacteriocins are located on the plasmids, apart from few which are chromosomal[y encoded. These bactericidal particles are species specific. They exert their lethal activity through adsorbtion to specific receptors located on the external surface of sensitive bacteria, followed by metabolic, biological and morphological changes resulting in the killing of such bacteria. This review summarises the classification, biochemical nature, morphology and mode of action of bacleriocins as well as their genetic determinants and the microbiological relevance of these bactericidal agents, i', 1997 Published by Elsevier Science Ltd

Bacteriocins of Escherichia coli: A Mini Review

Bacteriocins are antimicrobial peptides produced by certain bacteria that exhibit potent activities against closely related species, including pathogens. This review aimed to discuss and compare the results of academic research articles focused on the bacteriocins produced by Escherichia coli, shedding light on their diversity, mechanisms of action, and potential applications in various fields. Bacteriocins produced by E. coli strains have been found to vary in terms of their genetic determinants, structures, and modes of action. Through extensive research, several types of E. coli bacteriocins have been identified and characterized, including colicins, microcins, and other related peptides. Some bacteriocins act by disrupting the target cell membrane, leading to cell lysis, while others target essential cellular processes, such as DNA replication or protein synthesis. Understanding these mechanisms provides insights into the potential applications of E. coli bacteriocins as antibacterial agents or probiotics to fight against pathogens. Studies have explored their specific antimicrobial spectra, examining their efficacy against various bacterial strains, including antibiotic-resistant pathogens. Additionally, investigations into their regulation, biosynthesis, and mode of action have contributed to a better understanding of their potential as therapeutic agents. Furthermore, the potential applications of E. coli bacteriocins extend beyond the medical field. Research has demonstrated their ability to control foodborne pathogens and spoilage bacteria, making them promising as natural food preservatives. Moreover, their potential use in biotechnology, agriculture, and environmental protection has been explored, emphasizing their versatility and potential industrial applications. This review paper discussed and compared the results of academic research concerning E. coli bacteriocins, providing insights into their diversity, mechanisms of action, and potential applications. Further studies on E. coli bacteriocins will not only contribute to the understanding of bacterial interactions but may also pave the way for novel antimicrobial strategies and biotechnological advancements.