Genome-Wide Screening of Genes Whose Enhanced Expression Affects Glycogen Accumulation in Escherichia coli

Abstract

Using a systematic and comprehensive gene expression library (the ASKA library), we have carried out a genome-wide screening of the genes whose increased plasmid-directed expression affected glycogen metabolism in Escherichia coli. Of the 4123 clones of the collection, 28 displayed a glycogen-excess phenotype, whereas 58 displayed a glycogen-deficient phenotype. The genes whose enhanced expression affected glycogen accumulation were classified into various functional categories including carbon sensing, transport and metabolism, general stress and stringent responses, factors determining intercellular communication, aggregative and social behaviour, nitrogen metabolism and energy status. Noteworthy, one-third of them were genes about which little or nothing is known. We propose an integrated metabolic model wherein E. coli glycogen metabolism is highly interconnected with a wide variety of cellular processes and is tightly adjusted to the nutritional and energetic status of the cell. Furthermore, we provide clues about possible biological roles of genes of still unknown functions.

Genome-Wide Screening with Hydroxyurea Reveals a Link between Nonessential Ribosomal Proteins and Reactive Oxygen Species Production

“…The Keio Collection has been used by many groups to observe the effects of gene deletions under specific conditions of interest. These studies have included the determination of mutations affecting antibiotic hypersensitivity (2,3), swarming motility (4), biofilm formation (5), growth in human blood (6), recipient ability in plasmid conjugation (7), cysteine tolerance and production (8), colicin import and cytotoxicity (9), de-ethylation of 7-ethoxycoumarin (10), and glycogen metabolism (11). In most of these studies, the sets of relevant gene deletions show enrichment for specific cellular functions linked to the conditions of the screen.…”

Glycogen is the primary source of glucose during the lag phase of E. coli proliferation

“…This indicates that after 8 hr, glucose uptake is not mainly used for cell proliferation, and there should be another destination for these sugar groups. We should not forget that there is another pathway connected with G6P, glycogen metabolism pathway [18,21,22], which is an intracellular sugar storage mechanism. This suggests that, in this phase, glucose is changed to glycogen.…”

“…Numerous studies focused on glycogen storage diseases in human [10][11][12][13][14][15][16]. There are also many studies on glycogen network in prokaryotes [17][18][19][20][21][22][23][24][25], which serve as simple models of glycogen storage diseases in mammals, but most of them focus on glycogen network only. On the other hand, in the area of metabolic engineering, the most studied carbohydrate metabolic pathways are EMD (the Embden-Meyerhof-Parnas pathway), PPP and ED (the Entner-Doudoroff pathway) [26], but seldom glycogen network was taken into account in biological or computational central metabolism models [27][28][29][30][31][32][33][34][35].…”

Recent insight in α-glucan metabolism in probiotic bacteria

“…Glycogen metabolism contributes to energy storage and other physiological functions in some prokaryotes, including colonization persistence (Jones et al 2008;Busuioc et al 2009), and serves as a carbon capacitor that regulates downstream carbon fluxes (Belanger & Hatfull 1999). In addition, glycogen metabolism is involved in major cellular processes, such as carbohydrate metabolism, energy production, stress response and cell-cell communication (Eydallin et al 2007;Eydallin et al 2010). Altogether, available data suggest that glycogen metabolism potentially contributes to the survival and probiotic activities of lactobacilliand possibly other probiotic microorganisms in the GI environment.…”