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Cell-Cell Communication in Lactic Acid Bacteria
Published in Marcela Albuquerque Cavalcanti de Albuquerque, Alejandra de Moreno de LeBlanc, Jean Guy LeBlanc, Raquel Bedani, Lactic Acid Bacteria, 2020
Emília Maria França Lima, Beatriz Ximena Valencia Quecán, Luciana Rodrigues da Cunha, Bernadette Dora Gombossy de Melo Franco, Uelinton Manoel Pinto
The signaling molecules may be different according to each bacterial group, as shown in Table 1. The phenomenon has been extensively studied in Gram-negative bacteria, in which signaling is commonly mediated by acylated homoserine lactone molecules (AHLs), known as auto-inducer-1 (AI-1) (Kuipers 1998, Williams 2007, Papenfort and Bassler 2016). However, in Gram-positive bacteria, signaling usually occurs by auto-inducing peptides (AIP) (Kleerebezem et al. 1997, Banerjee and Ray 2017). New molecules have been discovered with the advancement of studies in the area, indicating the existence of alternative types of QS signaling mechanisms besides AHL and AIP (LaSarre and Federle 2013, Zhao et al. 2018). The molecule known as autoinducer 2 (AI-2) is associated with the quorum sensing in the two bacterial groups (Miller and Bassler 2001, Fuqua and Greenberg 2002), and there are also other molecules apart from these classes, such as the Pseudomonas quinolone signal (PQS) and the autoinducer-3 (AI-3) in Gram-negative bacteria.
Proteus
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
María José González, Pablo Zunino, Paola Scavone
Quorum sensing is the communication between bacterial cells in response to fluctuations in cell-population density and other inducers. The coordinate population response is controlled by diffusible molecules produced by individuals named autoinducers. N-acyl homoserine lactone (AHL) signaling molecules are utilized by several gram-negative species to sense population density and coordinate gene expression [62]. Despite P. mirabilis lacking a clear AHL synthase (LuxI) homologue, it encodes a LuxR family transcriptional regulator that seems to produce compounds with AHL-like activity [63,64]. The quorum-sensing molecule autoinducer 2 (AI-2), encoded by luxS, can mediate intra- and interspecies interactions. P. mirabilis possesses a luxS homologue and produces AI-2. However, Schneider et al. found that the mutation of luxS in P. mirabilis strain BB2000 does not significantly affect swarming, virulence factors production, or survival in a mouse model. This suggests that AI-2 does not contribute to pathogenicity, but it might influence gene expression in other species that use this signaling molecule [65]. Putrescine has also been proposed as an extracellular signal that is capable of mediating cell-to-cell communication [66]. Putrescine is a component of the outer membrane for some P. mirabilis strains [67]. If P. mirabilis utilizes putrescine for signaling, the bacteria may respond to putrescine produced by other species or scavenged from the host. P. mirabilis upregulates a putrescine transporter during experimental infection, but the signaling capabilities of this molecule remain unclear [68].
Quorum Sensing and Essential Oils
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Isabel Charlotte Soede, Gerhard Buchbauer
Besides the LUXRI system, Gram-negative bacteria also use other signaling pathways; one example is V. harveyi, a marine Gram-negative bacterium that also uses QS for bioluminescence. V. harveyi produces three different autoinducers: Cao and Meighen identified an N-acyl-homoserine-lactone, as an autoinducer (3-hydroxy-C4-HSL [Figure 16.1]) named harveyi autoinducer 1 (HAI-1) (Cao and Meighen, 1989). However, it was observed that the genes involved in the QS circuit are not homologous to the ones in the LUXRI system described earlier (Bassler et al., 1993).The second autoinducer discovered was named AI-2 (autoinducer 2), a furanosyl borate di-ester (Bassler et al., 1994), (Chen et al., 2002). Surette et al. identified the genes for luxS which is responsible for the production of AI-2 (Surette et al., 1999). LUXS binds periplasmatic to LUXP; this complex then interacts with a membrane-bound histidine kinase—LuxQ. Lux Q, just like LUXN has the same response regulator domains like those in two-component signal transduction systems in Gram-positive bacteria (Bassler et al., 1994).Henke and Bassler discovered a third QS system in V. harveyi—being named after the bacterial strain in which the system was primary discovered: Vibrio cholerae, a bacterium causing the disease cholera. The autoinducer (AI) is called cholerae autoinducer 1 (CAI-1), which is produced by CqsA (Cqs = cholerae quorum-sensing autoinducer) and binds to CqsS (=sensor) (Henke and Bassler, 2004).
Anti-biofilm activities of coumarin as quorum sensing inhibitor for Porphyromonas gingivalis
Published in Journal of Oral Microbiology, 2022
Zhiyan He, Wei Jiang, Yiting Jiang, Jiachen Dong, Zhongchen Song, Jianrong Xu, Wei Zhou
Biofilms are formed by microorganisms attached to a substratum and are composed of extracellular polysaccharides (EPS), proteins, lipids, and extracellular DNA [11]. Compared to planktonic bacteria, biofilm communities display specific properties such as being highly resistant to antimicrobial tolerance and better adapted to external environments [12]. Therefore, strategies focusing on eradicating the biofilm phenotype to avoid antimicrobial resistance have recently attracted much attention. Quorum sensing (QS) signals play an essential role in the biofilm development and dispersal [13]. QS is a well-known cell–cell communication system where bacteria produce and respond to signaling molecules known as autoinducers, sense the population density, and coordinate inter- and intra-population behaviour [14]. The bacterial autoinducers as signaling molecules in QS are autoinducer-1 (AI-1, acyl-homoserine lactones), autoinducing peptides (AIPs), and autoinducer-2 (AI-2, furanosyl borate diester) for cell-to-cell communications. Gram-negative bacteria employ acyl-homoserine lactones, whereas Gram-positive bacteria produce autoinducing peptides. Autoinducer-2, produced by the enzyme S-ribosylhomocysteine lyase (LuxS), is used for intra- and inter-species communication in both Gram-positive and Gram-negative bacteria [15–17]. As a new kind of potential antibiotic substitute, QS inhibitors have gained attention for inhibiting bacterial pathogenesis and not inducing antibiotic resistance. Hence, disrupting the QS process, including the application of quorum sensing inhibitors, is a critical way to control biofilm infections [18].
Autoinducer-2 of gut microbiota, a potential novel marker for human colorectal cancer, is associated with the activation of TNFSF9 signaling in macrophages
Published in OncoImmunology, 2019
Qing Li, Wei Peng, Jiao Wu, Xianfei Wang, Yixing Ren, Huan Li, Yan Peng, Xiaowei Tang, Xiangsheng Fu
The quorum sensing (QS) system, which is widely employed by bacteria, is an important mechanism of intercellular communication among bacterial species.15 The QS system enables bacteria to act as a group rather than an individual cell.16 Autoinducer-2 (AI-2), a major type of QS molecules that mediates the communication among interspecies,15 has the ability to regulate gene expression, virulence and biofilm formation of bacteria.1,17 The colon mucosal biofilm has been shown to be associated with an increased risk for sporadic CRC.18 Recent studies have revealed that AI-2 could potentially affect cytokine secretion of the host cells.19 Therefore, it is likely that AI-2 plays a role in the development and progression of CRC.
The ancestral stringent response potentiator, DksA has been adapted throughout Salmonella evolution to orchestrate the expression of metabolic, motility, and virulence pathways
Published in Gut Microbes, 2022
Helit Cohen, Boaz Adani, Emiliano Cohen, Bar Piscon, Shalhevet Azriel, Prerak Desai, Heike Bähre, Michael McClelland, Galia Rahav, Ohad Gal-Mor
Population-dependent behavior is mediated in many bacteria species by a process known as quorum sensing. Global changes in gene expression in response to quorum sensing are directed by the synthesis, release, and detection of small signal molecules termed autoinducers. Different bacterial phenotypes are affected by quorum sensing, including motility, biofilm formation, bioluminescence, and virulence.44 Autoinducer-2 (AI-2) is a universal signal molecule that could be synthesized and recognized by many Gram-positive and Gram-negative bacteria and plays a role in interspecies communication.45 In E. coli and S. Typhimurium, AI-2 is imported from the environment into the cell by the Lsr transporter system, encoded the genes lsrA, lsrB, lsrC, lsrD, lsrF, and lsrG. In addition, the adjacent and divergently transcribed genes lsrR and lsrK are responsible for the regulation of the lsr operon (Figure 9(a)).46 Interestingly, RNA-Seq data showed that the entire lsr regulon was downregulated in the absence of DksA in S. Typhimurium and in E. coli (Figure 9(b)). qRT-PCR analysis further confirmed these results and showed a decrease of 8- and 4-fold in the expression of lsrA (that encodes an ATP-binding protein for the AI-2 ABC transporter complex) and lsrR (encoding for a transcriptional regulator of the lsr operon), respectively, in the S. Typhimurium dksA mutant strain in comparison to the wildtype (Figure 9(c)). These results show for the first time that the universal quorum-sensing autoinducer AI-2 system in Salmonella and in E. coli is under the positive regulation of DksA.