Developmental Cycle: Differentiation of Legionella pneumophila
Rafael A. Garduño, Audrey Chong and Gary Faulkner
from: Legionella: Molecular Microbiology (Edited by: Klaus Heuner and Michele Swanson). Caister Academic Press, U.K. (2008)
Abstract
The discovery that L. pneumophila follows a developmental cycle, within which it differentiates into numerous forms with highly altered phenotypes, underlines the usefulness of this bacterium as an experimental model for the study of bacterial intracellular differentiation. The developmental cycle of Chlamydia species (which are obligate intracellular pathogens) constitutes the current paradigm of bacterial intracellular differentiation. However, unlike Chlamydia, L. pneumophila can grow in vitro and is amenable to mutagenesis and broad genetic screenings, enhancing our investigative options. Both the extracellular and the intracellular developmental cycles of L. pneumophila have been described. The comparative analysis of the differentiation steps associated with these two developmental cycles suggests that the extracellular cycle is an incomplete derivative of the intracellular one. We propose that L. pneumophila possesses a single developmental program controlled by known regulators of bacterial differentiation that respond to changes in the levels of amino acids in the environment, and to other as yet unidentified intracellular factors. However, these regulators seem to play unique roles in L. pneumophila that deviate from their known functionality in other bacteria read more ...
