Nanoparticles for Signaling in Biodiagnosis and Treatment of Infectious Diseases

Colino, Clara I.; Millán, Carmen Gutiérrez; Lanao, José M.

Gram-positive bacteria generally employ for communication small peptidic molecules named auto-inducing peptides (AIP). The synthesis of these peptide signals occurs in the cell ribosome and they undergo some modifications to reach a matured form. Specialized transporters are responsible for its active transport out of the cell. Detection of these peptide signals can occur either at the surface of the cell or intracellularly [149] . The simplest Gram-positive quorum sensing system was first discovered in Lactococcus lactis and Streptococcus pneumoniae [152] . A precursor of the auto-inducing peptide synthesized in the cell ribosome is modified and processed by an ATP-binding cassette (ABC) complex and then transported out of the cell At a certain AIP concentration, a two-component regulatory system transduces the signal through a phosphorylation cascade to response regulators that activate or repress target genes (Figure 4) [129, 149, 150, [152] [153] [154] . surface of the cell or intracellularly [149] . The simplest Gram-positive quorum sensing system was first discovered in Lactococcus lactis and Streptococcus pneumoniae [152] . A precursor of the autoinducing peptide synthesized in the cell ribosome is modified and processed by an ATP-binding cassette (ABC) complex and then transported out of the cell At a certain AIP concentration, a twocomponent regulatory system transduces the signal through a phosphorylation cascade to response regulators that activate or repress target genes ( Figure 4) [129, 149, 150, [152] [153] [154] . The third main category of autoinducers is AI-2, used by bacteria for interspecies communication. It is a furanosyl borate diester, produced by a LuxS protein [129, 156] . It has been identified in over 60 bacterial species although only a few of them possess receptors that sense and respond to the presence of AI-2. This autoinducer regulates the production of virulence factors in Vibrio vulnificus [157] [158] [159] , Serratia marcescens [159] and Clostridium perfringens [160] . However, the specific role of AI-2 in other species of bacteria remains unresolved [129, 130] .