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Category: Microbial Genetics and Molecular Biology; Bacterial Pathogenesis
Interdomain Cross Talk, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815578/9781555814045_Chap26-1.gif /docserver/preview/fulltext/10.1128/9781555815578/9781555814045_Chap26-2.gifAbstract:
This chapter defines four signaling categories that describe the different interdomain signaling mechanisms. These mechanisms are: (i) one-way sensing—one organism senses and responds to a diffusible signal produced by a second organism; (ii) co-opting of a signal—one organism uses the signal produced by another to regulate its own gene expression; (iii) modulation of a signal—one organism alters the production or stability of a signal from another organism; and (iv) two-way communication—multiple signals are exchanged between organisms. Pseudomonas aeruginosa produces two acylhomoserine lactones (AHLs) signals, 3-oxo-C12-homoserine lactone (3-O-C12- HSL) and C4-homoserine lactone (C4-HSL). The increased virulence in the presence of dynorphin is due to induction of the pqs biosynthetic operon, which leads to an increased production of hydroxy-alkylquinolones, including the P. aeruginosa quinolone signal (PQS) quorum-sensing molecule, which regulates a number of cytotoxic factors. Genetic and biochemical experiments indicated that P. aeruginosa 3-O-C12-HSL, described for its role in quorum sensing, is sufficient to suppress C. albicans hypha formation. Although the chapter has focused on signaling interactions that involve molecules whose primary role appears to be the transmission of information, there are likely many other signals, such as metabolites or pH and oxygen gradients, that may play equally important roles in the regulation of processes important during interdomain interactions. Physical interactions between organisms may also be important for communication within mixed species communities.
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Different types of interdomain signaling interactions. (A) One-way communication describes instances in which one organism responds to a signal produced by another organism. (B) Co-opting of a signal occurs when one organism specifically uses the signaling molecule of another to regulate gene expression. (C) Modulation of a signal by another organism can either stimulate or dampen the elicited response. (D) Two-way communication describes a chemical conversation between two organisms. The signal producer is depicted as the shaded form.
Diffusible molecules that participate in interdomain signaling interactions. The compounds on the left are bacterially derived; eukaryotic organisms produce the molecules on the right. The R group on the AHL and 3-O-AHL represents acyl chains from C=4 to C=16.
P. aeruginosa and C. albicans responses to secreted chemical signals.