The regulation of microcin B, C and J operons

Moreno, Felipe; González-Pastor, José Eduardo; Baquero, María Rosario; Bravo, Daniel

doi:10.1016/s0300-9084(02)01452-9

Cited by 39 publications

(45 citation statements)

References 63 publications

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“…Autoinducing peptides are involved in intercellular communication in gram-positive bacteria, and many of these peptides are exported by dedicated systems and finally sensed by other cells via membrane-located receptors. The production-biosynthesis, maturation, and secretion of colicins or microcins (83,327) into the medium by E. coli are encoded by gene clusters organized in operons that are silent/repressed during exponential growth and are induced/derepressed when cells sense nutrient starvation and stop their exponential growth (275). It could be of interest in the future to find out whether the E. coli strains that are resident in the intestinal microbiota possess a quorum-sensing system that senses the presence of these pathogens and in turn controls the production and secretion of antimicrobial molecules.…”

Section: Discussionmentioning

confidence: 99%

“…Microcins are a miscellaneous group of low-molecular-mass antibiotics (molecular mass less than 10 kDa), whereas colicins are much bigger, from 25 to 80 kDa. All colicins and some microcins are encoded by gene clusters organized in operons, whereas other microcins are encoded on the chromosome of produced bacteria (275). All the bacteria encoding microcins or colicins have immunity towards the antibiotics that they produce.…”

Section: Barrier Effect Against Pathogensmentioning

confidence: 99%

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The Front Line of Enteric Host Defense against Unwelcome Intrusion of Harmful Microorganisms: Mucins, Antimicrobial Peptides, and Microbiota

2006

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SUMMARY The intestinal tract is a complex ecosystem that combines resident microbiota and the cells of various phenotypes with complex metabolic activities that line the epithelial wall. The intestinal cells that make up the epithelium provide physical and chemical barriers that protect the host against the unwanted intrusion of microorganisms that hijack the cellular molecules and signaling pathways of the host and become pathogenic. Some of the organisms making up the intestinal microbiota also have microbicidal effects that contribute to the barrier against enteric pathogens. This review describes the two cell lineages present in the intestinal epithelium: the goblet cells and the Paneth cells, both of which play a pivotal role in the first line of enteric defense by producing mucus and antimicrobial peptides, respectively. We also analyze recent insights into the intestinal microbiota and the mechanisms by which some resident species act as a barrier to enteric pathogens. Moreover, this review examines whether the cells producing mucins or antimicrobial peptides and the resident microbiota act in partnership and whether they function individually and/or synergistically to provide the host with an effective front line of defense against harmful enteric pathogens.

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Section: Discussionmentioning

confidence: 99%

Section: Barrier Effect Against Pathogensmentioning

confidence: 99%

The Front Line of Enteric Host Defense against Unwelcome Intrusion of Harmful Microorganisms: Mucins, Antimicrobial Peptides, and Microbiota

2006

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“…Microcins are a class of small (Ͻ10 kDa) ribosomally synthesized peptide antibiotics produced by Enterobacteriaceae (1). Whereas some microcins are active as unmodified peptides (2), others are produced as polypeptide precursors that are heavily modified by dedicated maturation enzymes (3).…”

mentioning

confidence: 99%

Aspartyl-tRNA Synthetase Is the Target of Peptide Nucleotide Antibiotic Microcin C

Metlitskaya

Kazakov

Kommer

et al. 2006

Journal of Biological Chemistry

142

157

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Microcin C is a ribosome-synthesized heptapeptide that contains a modified adenosine monophosphate covalently attached to the C-terminal aspartate. Microcin C is a potent inhibitor of bacterial cell growth. Based on the in vivo kinetics of inhibition of macromolecular synthesis, Microcin C targets translation, through a mechanism that remained undefined. Here, we show that Microcin C is a subject of specific degradation inside the sensitive cell. The product of degradation, a modified aspartyl-adenylate containing an N-acylphosphoramidate linkage, strongly inhibits translation by blocking the function of aspartyl-tRNA synthetase.Microcins are a class of small (Ͻ10 kDa) ribosomally synthesized peptide antibiotics produced by Enterobacteriaceae (1). Whereas some microcins are active as unmodified peptides (2), others are produced as polypeptide precursors that are heavily modified by dedicated maturation enzymes (3). Interest is attached to such post-translationally modified microcins due to their highly unusual structures and the fact that they target important cellular processes that are attractive targets for antibacterial drug development.Genes responsible for microcin production are usually plasmidborne. Plasmids encoding microcin structural and maturation genes also encode determinants of immunity specific to the microcin produced. Based on cross-immunity, post-translationally modified microcins can be subdivided into the B, C, and J types. Microcin B (MccB) 4 is a 43-residue peptide with 8 thiazole and oxazole rings that are synthesized by the McbBCD maturation enzyme complex from multiple serine and cysteine residues present in the MccB precursor (4). MccB is a potent inhibitor of DNA gyrase; it traps the enzyme at the stage of DNA strand passage (5). Microcin J, a 21-amino acid peptide, contains an unusual lactam bond between its N-terminal glycine and the ␦-carboxyl group of an internal glutamate; it assumes a highly unusual threaded-lasso structure (6 -8). MccJ inhibits bacterial RNA polymerase by occluding a narrow channel that is used to traffic transcription substrates, NTPs, to the catalytic center of the enzyme (9, 10).The structure of the subject of this study, Microcin C (McC) is shown in Fig. 1A. McC is a heptapeptide containing a modified adenosine monophosphate covalently attached to its C terminus through an N-acylphosphoramidate linkage (11, 12). The phosphoramidate group of the nucleotide part of McC is additionally modified by a propylamine group. Additionally, in mature McC, the peptide moiety, which is encoded by the mccA gene, is modified and the C-terminal asparagine residue specified by mccA is converted to an aspartate (18, 19), through an unknown mechanism. In vivo, McC appears to target translation (12). Guijarro et al. (12) also reported that large concentrations of McC, as well as of synthetic peptide of the same sequence but without the nucleotide modification, mildly inhibit translation in vitro. They therefore concluded that the peptide part of McC is responsible for transl...

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“…Plasmids carrying microcin structural genes also provide immunity to the microcin produced. Some microcins are heavily modified by dedicated maturation enzymes that are also encoded by genes carried on plasmids that harbor microcin structural and immunity genes (9).…”

mentioning

confidence: 99%

Amino Acid Residues Required for Maturation, Cell Uptake, and Processing of Translation Inhibitor Microcin C

2007

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The regulation of microcin B, C and J operons

Cited by 39 publications

References 63 publications

The Front Line of Enteric Host Defense against Unwelcome Intrusion of Harmful Microorganisms: Mucins, Antimicrobial Peptides, and Microbiota

The Front Line of Enteric Host Defense against Unwelcome Intrusion of Harmful Microorganisms: Mucins, Antimicrobial Peptides, and Microbiota

Aspartyl-tRNA Synthetase Is the Target of Peptide Nucleotide Antibiotic Microcin C

Amino Acid Residues Required for Maturation, Cell Uptake, and Processing of Translation Inhibitor Microcin C

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