Bacterial Evolution by Intelligent Design

Abstract

In a process called quorum sensing, bacteria produce and secrete certain signaling compounds (called autoinducers) that bind to receptors on other bacteria and activate transcription of certain genes. A clever genetic selection yields a new quorum-sensing transcriptional regulator that marches to the beat of a different drummer.

Theoretical and structural analysis of the active site of the transcriptional regulators LasR and TraR, using molecular docking methodology for identifying potential analogues of acyl homoserine lactones (AHLs) with anti-quorum sensing activity

“…The alignment was generated using Clustal-W. LuxR [47], this remote homology may be related to the divergent evolution of each one. Such differences exist among the likely transcriptional regulators since each system has been optimized to provide survival in the specialized niche in which a particular species of bacteria reside [10,48]. In Table 1 is depicted some gram-negative bacteria with their respective regulatory proteins and their specific autoinducers (AI) [19,49].…”

“…These chemicals signals can stimulate diverse kinds of behaviors, including bioluminescence, horizontal transfer of DNA, biofilm formation, production of pathogenic factors, antibiotics resistance, and other secondary metabolites, among others [7][8][9][10]. This type of behavior in bacterium is now known as quorum sensing (QS).…”

Diverse Profiles of AI-1 Type Quorum Sensing Molecules in Cultivable Bacteria from the Mangrove (Kandelia obovata) Rhizosphere Environment

“…This suggests a dominance of longer-chain AHLs associated with the mangrove root species, where moderate acid pH predominates. In addition to the above-mentioned points, secreting medium- and long-chain AHL molecules could be an intelligent behavior of bacteria balancing the energy expended on self-preservation and ecological function (Winans, 2006; Jia et al, 2016). This hypothesis still needs to be further confirmed in future studies.…”

Single Cell Time-resolved Quorum Responses Reveal Dependence on Cell Density and Configuration

“…A highly ordered array of bundled optical imaging fibers (Schott, Elmsford, NY) containing ϳ50,000 individual fibers 3.1 m in diameter was polished using a series of lapping films (30,15,9,6, 3, 1, and 0.5 m) on a Multiprep fiber polisher from Allied High Tech Products, Inc. (Rancho Dominguez, CA). The bundle was subsequently etched by placing one end in 0.025 M HCl for 1 min and 45 s, creating wells that were about 2.5 m deep (26,30).…”

“…Expression of quorum-controlled genes is negligible or absent at low cellular density. When the number of bacteria in an environment reaches a critical level, the AI in the medium exceeds a threshold concentration and binds to regulatory receptor proteins, and the AI-receptor complex induces or represses the expression of genes that are under quorum regulation (5)(6)(7)(8)(9). The AI gene is usually one of the target genes under quorum control, creating a positive feedback loop for AI production, which causes a spike in AI expression.…”