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Quorum Sensing
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Archisman Bhunia, Kumar Narayan, Abhilasha Singh, Asmeeta Sircar, Nivedita Chatterjee
These signaling molecules are derivatives of several chemical classes and are majorly categorized into (1) fatty acid derivatives and (2) short peptides and amino acids (Whitehead et al., 2001). These signaling molecules identified within the microbes are N-acyl homoserine lactones (AHLs) in gram-negative bacteria, post-transcriptionally modified autoinducing oligopeptides (AIPs) in gram-positive bacteria, and a class of 4,5-dihydroxy-2,3-pentonedione derivatives (called autoinducer-2, i.e., AI-2) in gram-negative and gram-positive bacteria (Li and Nair, 2012). Another type of autoinducer, AI-3, was identified from the isolates of enterohemorrhagic Escherichia coli (EHEC) O157:H7 spent media (Sperandio et al., 2003). However, its presence in gram-positive bacteria is not yet documented.
Introduction
Published in James E. Ferrell, Systems Biology of Cell Signaling, 2021
Three specific examples of two-component systems are shown in Figure 1.2. The simplest of these is the quorum-sensing (Qse) pathway. The pathway is activated by one of several hormone-like small molecules, which include (1) a boron-containing compound called autoinducer-2 (AI-2), which is released by neighboring bacteria and used for both intraspecies and interspecies communication; (2) an as-yet unidentified bacterial factor termed autoinducer-3 (AI-3); and (3) the catecholamines epinephrine and norepinephrine, small molecules used as hormones and neurotransmitters by animals that can also mediate inter-kingdom communication between a host animal and the bacteria living within its gut. These stimulus molecules act by binding to a transmembrane receptor protein, QseC. QseC possesses a modular histidine kinase domain, and this domain is similar in sequence to the kinase domains of all of the 28 other E. coli histidine kinases (but not to the eukaryotic serine/threonine or tyrosine kinases). The activated receptor autophosphorylates at a specific conserved histidine residue and then transfers this phosphate to an aspartate residue on a response regulator, the DNA-binding protein QseB. When phosphorylated, QseB activates the transcription of specific flagellar genes. The protein phosphorylation is probably reversed by the kinase itself, in the case of the histidine autophosphorylation, and non-enzymatically, in the case of the aspartate phosphorylation of the response regulator. Thus, an input (the concentration of the small molecule receptor-binding ligand) gets converted into an output (changes in gene expression) via a simple linear signal transduction pathway with only two components (QseC and QseB).
Metabolic Regulation in Response to Growth Environment
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
Quorum sensing is a cell-to-cell communication (Waters and Bassler 2005), where the signal molecules are acyl-homoserine lactones (AHL) synthesized by LuxI-type enzyme. At high cell density cultivations, LuxR- type regulator plays a role for the positive feedback in association with AHL when its concentration exceeds a threshold level (Timmermans and van Melderen 2010). The quorum sensing is the sensing of cell density, where in E. coli, CyaR represses luxS gene which encodes autoinducer-2 synthase (Delay and Gottesman 2009).
Structural variations on Salmonella biofilm by exposition to river water
Published in International Journal of Environmental Health Research, 2021
Contreras-Soto Mb, Medrano-Félix Ja, Sañudo-Barajas Ja, Vélez-de la Rocha R, Ibarra-Rodríguez Jr, Martínez-Urtaza J, Chaidez C, Castro-del Campo N
The presence of ribose, was detected in all strains and in all conditions, being higher in planktonic bacteria, where Typhimurium 14028 and Infantis Cli S-304 were the strains that had the greatest amount of this compound. The 5-carbon sugar ribose is an important component of nucleotides and is found in RNA; it is known that within the biofilm formation there are cells in the planktonic state and cells segmented to the exopolysaccharide matrix; this might explain the detection of ribose as a component of biofilms in this study. Interestingly, diverse studies demonstrated that D-ribose inhibited AI-2 (autoinducer 2) that induced biofilm growth and co-aggregation in Gram negative and Gram positive bacteria (Jang et al. 2013; Lee et al. 2015; Cho et al. 2016; Sintim and Gürsoy 2016; Liu L et al. 2017). There is no information about the role of ribose in Salmonella biofilms; however, the literature shows ribose as a biofilm inhibiting agent; therefore, these findings open an important source of opportunities to expand scientific search for knowledge about biofilm formation and composition in Salmonella and other enterobacterias.