Functional Roles of Non-membrane Lipids in Bacterial Signaling
Bacteria produce some lipids and lipid-related compounds that function as signals for intercellular communication among prokaryotes or even in inter-kingdom communication (i.e., between prokaryotes and eukaryotes). Most of these lipidic signals participate in quorum-sensing regulation, a process that is dependent on cell density and enables a coordinated response within the population. The number and variety of bacterial non-membrane lipids that have been found to function as molecular signals is increasing and includes unsaturated fatty acids, fatty acid esters, acyl-based molecules such as N-acylhomoserine lactones and γ-butyrolactones, alkyl-based compounds such as quinolones and dialkylresorcinols, or alkane-derived signals such as α-hydroxyketones. Most of these signals are amphipathic and can diffuse through membranes and some of them are volatile. They are synthesized from common metabolites including intermediates of lipid metabolism and are recognized by membrane-bound or cytosolic receptors that trigger specific signal transduction responses. These signals regulate important bacterial traits such as motility, production of antimicrobials, expression of virulence factors, and biofilm formation. Some of these bacterial lipids induce immune responses in eukaryotic organisms.
KeywordsQuorum Sense Fatty Acid Ester Quorum Sense System Methyl Ketone Diffusible Signal Factor
Work on MJS’s lab was funded by Grant BIO2013-42801-P. NCM was supported by an FPU fellowship from the Spanish Ministry of Education and Science. Work on IMLL’s lab was funded by Dirección General de Asuntos del Personal Académico-Universidad Nacional Autónoma de México (DGAPA-UNAM; PAPIIT IN202616).
- Drees SL, Li C, Prasetya F, Saleem M, Dreveny I, Williams P, Hennecke U, Emsley J, Fetzner S (2016) PqsBC, a condensing enzyme in the biosynthesis of the Pseudomonas aeruginosa quinolone signal: crystal structure, inhibition, and reaction mechanism. J Biol Chem 291:6610–6624CrossRefPubMedPubMedCentralGoogle Scholar
- Kakkar A, Nizampatnam NR, Kondreddy A, Pradhan BB, Chatterjee S (2015) Xanthomonas campestris cell-cell signalling molecule DSF (diffusible signal factor) elicits innate immunity in plants and is suppressed by the exopolysaccharide xanthan. J Exp Bot 66:6697–6714CrossRefPubMedPubMedCentralGoogle Scholar
- Park HB, Lee B, Kloepper JW, Ryu CM (2013) One shot-two pathogens blocked: exposure of Arabidopsis to hexadecane, a long chain volatile organic compound, confers induced resistance against both Pectobacterium carotovorum and Pseudomonas syringae. Plant Signal Behav 8:e24619CrossRefPubMedGoogle Scholar
- Schell U, Simon S, Sahr T, Hager D, Albers MF, Kessler A, Fahrnbauer F, Trauner D, Hedberg C, Buchrieser C, Hilbi H (2016) The alpha-hydroxyketone LAI-1 regulates motility, Lqs-dependent phosphorylation signalling and gene expression of Legionella pneumophila. Mol Microbiol 99:778–793CrossRefPubMedGoogle Scholar
- Schenk ST, Hernandez-Reyes C, Samans B, Stein E, Neumann C, Schikora M, Reichelt M, Mithofer A, Becker A, Kogel KH, Schikora A (2014) N-acyl-homoserine lactone primes plants for cell wall reinforcement and induces resistance to bacterial pathogens via the salicylic acid/oxylipin pathway. Plant Cell 26:2708–2723CrossRefPubMedPubMedCentralGoogle Scholar