Developmental Gene Regulation
Ramya Rajagopalan, Zaara Sarwar, Anthony G. Garza and Lee Kroos
from: Myxobacteria: Genomics, Cellular and Molecular Biology (Edited by: Zhaomin Yang and Penelope I. Higgs). Caister Academic Press, U.K. (2014)
Starvation induces Myxococcus xanthus cells to glide into aggregates and form multicellular fruiting bodies in which some cells differentiate from rods to spores. The gene regulatory network controlling this developmental process involves three interconnected modules. The first module is a cascade of eukaryotic-like enhancer binding proteins that activate early genes in response to starvation, although products of some of those genes function later in development. The second module depends on the first, linking it indirectly to starvation, but other pathways directly link the second module to starvation, and govern accumulation of MrpC and its truncated form MrpC2, which directly activate transcription of fruA, the gene encoding the key component of the third module. Activity of FruA is governed by short-range C-signaling between cells, which is believed to increase as cells become aligned in aggregates. FruA and MrpC2 bind cooperatively to promoter regions of several late genes, subjecting them to control by the Mrp and FruA modules. Among these late genes is the dev operon, whose products somehow control expression of genes required for spore formation. Feedback loops within modules and between modules reinforce developmental progression. Interestingly, some of the key regulators appear to have been acquired by lateral gene transfer and are not conserved in distantly-related mxyobacteria that form fruiting bodies read more ...