Analysis of the Escherichia coli glycogen gene cluster suggests that catabolic enzymes are encoded among the biosynthetic genes

Romeo, Tony; Kumar, Anil; Preiss, Jack

doi:10.1016/0378-1119(88)90208-9

Cited by 110 publications

(88 citation statements)

References 42 publications

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“…In this organism, the key enzymes for glycogen degradation, glycogen phosphorylase and debranching enzyme, are present and active throughout growth, even when there is net glycogen accumulation (Dauvillée et al, 2005). In agreement with these observations, the genes encoding the E. coli proteins involved in glycogen degradation and synthesis (glgC, glgA, glgB, glgP and glgX) are clustered and arranged in operons (Romeo et al, 1988). However, in C. glutamicum, the glg genes or their putative homologues are obviously scattered within the genome (Seibold et al, 2007).…”

Section: Discussionsupporting

confidence: 63%

“…the introduction of a-1,6-glycosidiclinkages in the polymer, is catalysed by the glycogenbranching enzyme (Abad et al, 2002). The genes encoding the three glycogen-synthesizing enzymes are located in a cluster together with genes encoding enzymes involved in degradation of glycogen (Romeo et al, 1988). Glycogen degradation in E. coli is accomplished by the interplay of four enzymes (Fig.…”

Section: Introductionmentioning

confidence: 99%

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The glgX gene product of Corynebacterium glutamicum is required for glycogen degradation and for fast adaptation to hyperosmotic stress

Seibold

Eikmanns

2007

Microbiology

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Corynebacterium glutamicum cells growing in medium containing sugars accumulate glycogen in the early exponential-growth phase, and start to degrade this polymer at entry into the stationary phase. In a first attempt to investigate glycogen degradation, the C. glutamicum glgX gene, which encodes a protein with 46 % identity to the isoamylase-type debranching enzyme of Escherichia coli, was analysed, expressed and inactivated. The purified C. glutamicum gene product showed debranching activity towards glycogen, amylopectin and starch. Chromosomal inactivation of glgX in C. glutamicum wild-type led to slower growth and to a higher intracellular glycogen pool throughout growth, when compared to those in the parental strain. This result suggests that glycogen synthesis and degradation occur simultaneously in C. glutamicum. When exposed to hyperosmotic shock, C. glutamicum rapidly degrades glycogen, and at the same time, synthesizes the osmoprotectant trehalose. The glgX mutant, however, synthesized only minor amounts of trehalose throughout cultivation, and its growth ceased after hyperosmotic shock. Taken together, the results indicate that the glgX gene product is essential for glycogen degradation in C. glutamicum, that glycogen is constantly recycled in C. glutamicum, and that it serves as a carbon store for trehalose synthesis via the TreYZ pathway after hyperosmotic shock.

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Section: Discussionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

The glgX gene product of Corynebacterium glutamicum is required for glycogen degradation and for fast adaptation to hyperosmotic stress

Seibold

Eikmanns

2007

Microbiology

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“…However, a key enzyme in glycogen metabolism, glycogen phosphorylase (EC 2.4.1.1), is known to be allosterically inhibited by ADPglucose and activated by AMP (5). Glycogen phosphorylase is encoded by a gene that has been alternatively designated glgY or glgP, which is located distal to glgA within the glgCAY operon (27,37). A second enzyme that is believed to be important for the metabolism of intracellular glycogen in E. coli is the glycogen debranching enzyme (EC 3.2.1.-), which hydrolyzes the ␣-1,6 branches of glycogen which has first been partially depolymerized by phosphorylase (11).…”

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confidence: 99%

“…A second enzyme that is believed to be important for the metabolism of intracellular glycogen in E. coli is the glycogen debranching enzyme (EC 3.2.1.-), which hydrolyzes the ␣-1,6 branches of glycogen which has first been partially depolymerized by phosphorylase (11). The glgBX operon is located upstream from and in tandem with glgCAY and includes the gene for glycogen branching enzyme (glgB [3]) and possibly the gene for glycogen debranching enzyme or another catabolic glucanase (27). This was previously hypothesized on the basis of the similarity of the deduced amino acid sequence of GlgX to sequences of glucanotransferases and hydrolases and the fact that glgX was not required for glucan biosynthesis (27).…”

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confidence: 99%

Coordinate genetic regulation of glycogen catabolism and biosynthesis in Escherichia coli via the CsrA gene product

1996

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The carbon storage regulator gene, csrA, encodes a factor which negatively modulates the expression of the glycogen biosynthetic gene glgC by enhancing the decay of its mRNA (M. Y. Liu, H. Yang, and T. Romeo, J. Bacteriol. 177:2663-2672, 1995). When endogenous glycogen levels in isogenic csrA ؉ and csrA::kanR strains were quantified during the growth curve, both the rate of glycogen accumulation during late exponential or early stationary phase and its subsequent rate of degradation were found to be greatly accelerated by the csrA::kanR mutation. The expression of the biosynthetic genes glgA (glycogen synthase) and glgS was observed to be negatively modulated via csrA. Thus, csrA is now known to control all of the known glycogen biosynthetic genes (glg), which are located in three different operons. Similarly, the expression of the degradative enzyme glycogen phosphorylase, which is encoded by glgY, was found to be negatively regulated via csrA in vivo. The in vitro transcription-translation of glgY was also specifically inhibited by the purified CsrA gene product. These results demonstrate that localization of glycogen biosynthetic and degradative genes within the Escherichia coli glgCAY operon facilitates their coordinate genetic regulation, as previously hypothesized (T. Romeo, A. Kumar, and J. Preiss, Gene 70:363-376, 1988). The csrA gene did not affect glycogen debranching enzyme, which is now shown to be encoded by the gene glgX.One feature of the complex adaptive response which occurs when Escherichia coli or various other bacteria enter stationary phase is the increased expression of genes involved in the biosynthesis of glycogen (reviewed in references 12 and 20-22). A shortage of a nutrient such as nitrogen in the presence of excess carbon is particularly effective in causing the intracellular accumulation of glycogen, which can be metabolized as an endogenous carbon and energy source. The regulatory mechanisms for glycogen synthesis in E. coli include (i) allosteric control via the metabolites AMP and fructose-1,6-bisphosphate of the committed step of the pathway, catalyzed by ADPglucose pyrophosphorylase (EC 2.7.7.27); (ii) stimulation of the genetic expression of glgC (which encodes ADPglucose pyrophosphorylase [2]) and glgA (which encodes glycogen synthase [EC 2.4.1.21] [13]) by guanosine 3Ј-bisphosphate 5Ј-bisphosphate and cyclic AMP (cAMP); and (iii) the transcriptional control of glgS, a monocistronic gene which stimulates glycogen synthesis in vivo, by cAMP and s (9, 20-22, 24, 28). We recently identified and characterized the csrA gene, which exerts a very strong negative effect on glycogen synthesis in E. coli (25,26). This gene encodes a 61-amino-acid protein, CsrA, which was shown to regulate the expression of glgB (encoding glycogen branching enzyme [EC 2.4.1.18]) and glgC (26). CsrA has been shown to be a factor which enhances the rate of decay of glgC mRNA via a novel though unresolved mechanism (16). The deduced amino acid sequence of CsrA is homologous to a diverse subset of RNA-bindin...

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“…contains an additional open reading frame, glgX, which has sequence similarity to the E. coli branching enzyme, as well as to glucan hydrolases and transferases (43,58). The gene order for these enzymes is glgY-glgA-glgC-glgX-glgB.…”

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Characterization of the Butyrivibrio fibrisolvens glgB gene, which encodes a glycogen-branching enzyme with starch-clearing activity

et al. 1991

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(calculated Mr, 73,875) with 46 to 50% sequence homology with other branching enzymes. A limited region of 12 amino acids showed sequence similarity to amylases and glucanotransferases. The B. fibrisolvens branching enzyme was not able to hydrolyze starch but stimulated phosphorylase a-mediated incorporation of glucose into a-1,4-glucan polymer 13.4-fold. The branching enzyme was purified to homogeneity by a simple two-step procedure; N-terminal sequence and amino acid composition determinations confirmed the deduced translational start and amino acid sequence of the open reading frame. The enzymatic properties of the purified enzyme were investigated. The enzyme transferred chains of 5 to 10 (optimum, 7) glucose units, using amylose and amylopectin as substrates, to produce a highly branched polymer.

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Analysis of the Escherichia coli glycogen gene cluster suggests that catabolic enzymes are encoded among the biosynthetic genes

Cited by 110 publications

References 42 publications

The glgX gene product of Corynebacterium glutamicum is required for glycogen degradation and for fast adaptation to hyperosmotic stress

The glgX gene product of Corynebacterium glutamicum is required for glycogen degradation and for fast adaptation to hyperosmotic stress

Coordinate genetic regulation of glycogen catabolism and biosynthesis in Escherichia coli via the CsrA gene product

Characterization of the Butyrivibrio fibrisolvens glgB gene, which encodes a glycogen-branching enzyme with starch-clearing activity

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