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Escherichia coli K-12 substr. MG1655 Pathway: glycogen degradation I
Inferred from experimentTraceable author statement to experimental support

Pathway diagram: glycogen degradation I

If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Locations of Mapped Genes:

Schematic showing all replicons, marked with selected genes

Genetic Regulation Schematic

Genetic regulation schematic for glycogen degradation I

Synonyms: glycogen catabolism I

Superclasses: BiosynthesisCarbohydrates BiosynthesisSugars Biosynthesis
Degradation/Utilization/AssimilationCarbohydrates DegradationPolysaccharides DegradationGlycogen Degradation
Degradation/Utilization/AssimilationPolymeric Compounds DegradationPolysaccharides DegradationGlycogen Degradation

General Background

In many bacteria including Escherichia coli glycogen is the primary carbon and energy storage compound. Evidence suggests that it may play a role in the long-term survival of the cell. In E. coli glycogen is stored in granules in the cytosol [AlonsoCasajus06]. It is biosynthesized in a highly regulated manner when carbon is plentiful, but other nutrients are limiting (see pathway glycogen biosynthesis I (from ADP-D-Glucose)). Glycogen is utilized when carbon sources become limiting. The regulation of endogenous glycogen metabolism in E. coli remains incompletely understood [Eydallin07, Montero09, Eydallin10, Montero11] and has been the subject of metabolic modeling studies [Park11, Yamamotoya12].

E. coli genes glgP and glgX are involved in glycogen degradation, whereas glgA, glgB and glgC are involved in glycogen biosynthesis. Earlier studies suggested that the glg genes for glycogen metabolism are clustered into two tandemly arranged operons, glgBX and glgCAP. However, more recent transcription studies in E. coli K-12 demonstrated that genes glgBXCAP are transcribed in a single transcriptional unit under the control of promoter sequences upstream of glgB. In addition, a promoter within glgC controls the expression of glgA and glgP. These transcription units are part of both the RelA and PhoP-PhoQ regulons [Montero11].

E. coli and Salmonella cannot grow on exogenous glycogen, starch, or pullulan), although they are able to grow on linear α-1,4-linked maltodextrins ranging in size from maltose to maltodextrins of up to about 20 glucose units in length (in Mayer and Boos [ECOSAL], see below).

About This Pathway

The glgP and glgX genes are involved in the initial breakdown of glycogen. During endogenous glycogen degradation, the glycogen phosphorylase product of gene glgP shortens the glycogen chains sequentially from their nonreducing end to produce a limit dextrin (also called a glycogen phosphorylase limit dextrin). Overexpression of glgP can decrease glycogen to undetectable levels, and the lowering of glycogen levels directly correlates with increases in the expression of glycogen phosphorylase activity. The debranching enzyme product of glgX removes α-1,6-linked branches that are a maximum of four glucosyl residues in length to produce a debranched limit dextrin (also called a debranched glycogen phosphorylase limit dextrin). It is therefore likely that GlgX releases maltotetraose from glycogen and also plays an important role in the production of maltotriose, an endogenous inducer of the maltose system (see below) [AlonsoCasajus06, Dauvillee05].

Further breakdown of the maltodextrin intermediates, maltotetraose, maltotriose and maltose involves the products of the maltose utilization genes malP, malZ and malQ. These genes are part of the maltose/maltodextrin regulon controlled by MalT, a transcriptional activator that is activated by maltotriose [Dippel05, AlonsoCasajus06, Lengsfeld09].

Maltodextrin phosphorylase encoded by malP phosphorylytically cleaves glucosyl residues from the nonreducing end of maltodextrins producing α-D-glucose-1-phosphate and a shortened maltodextrin. Maltotetraose is the smallest substrate, therefore the ultimate product of MalP action on a maltodextrin is the inducer maltotriose [AlonsoCasajus06, Dippel05]. α-D-glucose 1-phosphate is converted to α-D-glucose-6-phosphate by phosphoglucomutase encoded by gene pgm. α-D-glucose-6-phosphate can spontaneously convert to its β epimer and enter central metabolism as shown in the pathway link.

Maltodextrin glucosidase encoded by malZ can cleave α-D-glucose residues sequentially from the reducing end of maltodextrins, with the smallest substrate being maltotriose. In the case of maltotriose, the reaction products are α-D-glucose and maltose. The former compound is a source of glucose for the cell and can spontaneously epimerize to β-D-glucose ( α-D-glucopyranose ↔ β-D-glucopyranose) and enter central metabolism as shown in the pathway link. Although MalZ is a maltodextrin-specific enzyme, its exact role is unclear and it is not essential for maltose or maltodextrin utilization [AlonsoCasajus06, Lengsfeld09].

Amylomaltase encoded by malQ is a 4-α-glucanotransferase that is essential for maltose degradation. MalQ mutants are unable to grow on maltose. Amylomaltase preferentially removes glucose from the reducing ends of maltose and small maltodextrins, transferring the enzyme-bound dextrinyl residue to the nonreducing ends of other maltodextrins, thereby forming longer maltodextrins (in [Park11]). In this process the number of glucosidic linkages remains constant. Therefore MalQ can both degrade and synthesize the inducer maltotriose, allowing induction when the bacteria are grown on maltodextrins [AlonsoCasajus06]. The β-D-glucose formed is phosphorylated by glucokinase and the resulting β-D-glucose-6-phosphate enters glycolysis.

Reviews: Mayer, C. and W. Boos (2005) Hexose/Pentose and Hexitol/Pentitol Metabolism, Module 3.4.1 in [ECOSAL], Preiss, J. (2009) Glycogen: Biosynthesis and Regulation, Module 4.7.4 in [ECOSAL] and [Wang11, Schlegel02]

Created 20-Dec-1995 by Riley M, Marine Biological Laboratory
Last-Curated 25-Feb-2013 by Fulcher C, SRI International


AlonsoCasajus06: Alonso-Casajus N, Dauvillee D, Viale AM, Munoz FJ, Baroja-Fernandez E, Moran-Zorzano MT, Eydallin G, Ball S, Pozueta-Romero J (2006). "Glycogen phosphorylase, the product of the glgP Gene, catalyzes glycogen breakdown by removing glucose units from the nonreducing ends in Escherichia coli." J Bacteriol 188(14);5266-72. PMID: 16816199

Ball03: Ball SG, Morell MK (2003). "From bacterial glycogen to starch: understanding the biogenesis of the plant starch granule." Annu Rev Plant Biol 54;207-33. PMID: 14502990

Ball11: Ball S, Colleoni C, Cenci U, Raj JN, Tirtiaux C (2011). "The evolution of glycogen and starch metabolism in eukaryotes gives molecular clues to understand the establishment of plastid endosymbiosis." J Exp Bot 62(6);1775-801. PMID: 21220783

Buleon98: Buleon A, Colonna P, Planchot V, Ball S (1998). "Starch granules: structure and biosynthesis." Int J Biol Macromol 23(2);85-112. PMID: 9730163

Dauvillee05: Dauvillee D, Kinderf IS, Li Z, Kosar-Hashemi B, Samuel MS, Rampling L, Ball S, Morell MK (2005). "Role of the Escherichia coli glgX gene in glycogen metabolism." J Bacteriol 187(4);1465-73. PMID: 15687211

Dippel05: Dippel R, Boos W (2005). "The maltodextrin system of Escherichia coli: metabolism and transport." J Bacteriol 187(24);8322-31. PMID: 16321936

ECOSAL: "Escherichia coli and Salmonella: Cellular and Molecular Biology." Online edition.

Eydallin07: Eydallin G, Viale AM, Moran-Zorzano MT, Munoz FJ, Montero M, Baroja-Fernandez E, Pozueta-Romero J (2007). "Genome-wide screening of genes affecting glycogen metabolism in Escherichia coli K-12." FEBS Lett 581(16);2947-53. PMID: 17543954

Eydallin10: Eydallin G, Montero M, Almagro G, Sesma MT, Viale AM, Munoz FJ, Rahimpour M, Baroja-Fernandez E, Pozueta-Romero J (2010). "Genome-wide screening of genes whose enhanced expression affects glycogen accumulation in Escherichia coli." DNA Res 17(2);61-71. PMID: 20118147

Lengsfeld09: Lengsfeld C, Schonert S, Dippel R, Boos W (2009). "Glucose- and glucokinase-controlled mal gene expression in Escherichia coli." J Bacteriol 191(3);701-12. PMID: 19028900

Montero09: Montero M, Eydallin G, Viale AM, Almagro G, Munoz FJ, Rahimpour M, Sesma MT, Baroja-Fernandez E, Pozueta-Romero J (2009). "Escherichia coli glycogen metabolism is controlled by the PhoP-PhoQ regulatory system at submillimolar environmental Mg2+ concentrations, and is highly interconnected with a wide variety of cellular processes." Biochem J 424(1);129-41. PMID: 19702577

Montero11: Montero M, Almagro G, Eydallin G, Viale AM, Munoz FJ, Bahaji A, Li J, Rahimpour M, Baroja-Fernandez E, Pozueta-Romero J (2011). "Escherichia coli glycogen genes are organized in a single glgBXCAP transcriptional unit possessing an alternative suboperonic promoter within glgC that directs glgAP expression." Biochem J 433(1);107-17. PMID: 21029047

Park11: Park JT, Shim JH, Tran PL, Hong IH, Yong HU, Oktavina EF, Nguyen HD, Kim JW, Lee TS, Park SH, Boos W, Park KH (2011). "Role of maltose enzymes in glycogen synthesis by Escherichia coli." J Bacteriol 193(10);2517-26. PMID: 21421758

Schlegel02: Schlegel A, Bohm A, Lee SJ, Peist R, Decker K, Boos W (2002). "Network regulation of the Escherichia coli maltose system." J Mol Microbiol Biotechnol 4(3);301-7. PMID: 11931562

Shearer02: Shearer J, Graham TE (2002). "New perspectives on the storage and organization of muscle glycogen." Can J Appl Physiol 27(2);179-203. PMID: 12179957

Wang11: Wang L, Wise MJ (2011). "Glycogen with short average chain length enhances bacterial durability." Naturwissenschaften 98(9);719-29. PMID: 21808975

Yamamotoya12: Yamamotoya T, Dose H, Tian Z, Faure A, Toya Y, Honma M, Igarashi K, Nakahigashi K, Soga T, Mori H, Matsuno H (2012). "Glycogen is the primary source of glucose during the lag phase of E. coli proliferation." Biochim Biophys Acta 1824(12);1442-8. PMID: 22750467

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Adhya71: Adhya S, Schwartz M (1971). "Phosphoglucomutase mutants of Escherichia coli K-12." J Bacteriol 108(2);621-6. PMID: 4942754

Arora95: Arora KK, Pedersen PL (1995). "Glucokinase of Escherichia coli: induction in response to the stress of overexpressing foreign proteins." Arch Biochem Biophys 1995;319(2);574-8. PMID: 7786044

Asensio58: Asensio C, Sols A (1958). "Utilization and phosphorylation of sugars by Escherichia coli." Rev Esp Fisiol 14(4);269-75. PMID: 13658662

Asensio63: Asensio C, Avigad G, Horecker BL (1963). "Preferential galactose utilization in a mutant strain of E. coli." Arch Biochem Biophys 103;299-309. PMID: 14103281

Bartl99: Bartl F, Palm D, Schinzel R, Zundel G (1999). "Proton relay system in the active site of maltodextrinphosphorylase via hydrogen bonds with large proton polarizability: an FT-IR difference spectroscopy study." Eur Biophys J 28(3);200-7. PMID: 10232933

Becker94: Becker S, Palm D, Schinzel R (1994). "Dissecting differential binding in the forward and reverse reaction of Escherichia coli maltodextrin phosphorylase using 2-deoxyglucosyl substrates." J Biol Chem 269(4);2485-90. PMID: 7905479

Becker95: Becker S, Schnackerz KD, Schinzel R (1995). "A study of binary complexes of Escherichia coli maltodextrin phosphorylase: alpha-D-glucose 1-methylenephosphonate as a probe of pyridoxal 5'-phosphate-substrate interactions." Biochim Biophys Acta 1243(3);381-5. PMID: 7727513

Boeck96: Boeck B, Schinzel R (1996). "Purification and characterisation of an alpha-glucan phosphorylase from the thermophilic bacterium Thermus thermophilus." Eur J Biochem 239(1);150-5. PMID: 8706700

Boos98: Boos W, Shuman H (1998). "Maltose/maltodextrin system of Escherichia coli: transport, metabolism, and regulation." Microbiol Mol Biol Rev 62(1);204-29. PMID: 9529892

Brautaset98: Brautaset T, Petersen S, Valla S (1998). "An experimental study on carbon flow in Escherichia coli as a function of kinetic properties and expression levels of the enzyme phosphoglucomutase." Biotechnol Bioeng 58(2-3);299-302. PMID: 10191405

BRENDA14: BRENDA team (2014). Imported from BRENDA version existing on Aug 2014.

Britton68: Britton HG, Clarke JB (1968). "The mechanism of the phosphoglucomutase reaction. Studies on rabbit muscle phosphoglucomutase with flux techniques." Biochem J 110(2);161-80. PMID: 5726186

Buchbinder01: Buchbinder JL, Rath VL, Fletterick RJ (2001). "Structural relationships among regulated and unregulated phosphorylases." Annu Rev Biophys Biomol Struct 30;191-209. PMID: 11340058

Campagnolo08: Campagnolo M, Campa C, Zorzi RD, Wuerges J, Geremia S (2008). "X-ray studies on ternary complexes of maltodextrin phosphorylase." Arch Biochem Biophys 471(1);11-9. PMID: 18164678

Chao69: Chao J, Johnson GF, Graves DJ (1969). "Kinetic mechanism of maltodextrin phosphorylase." Biochemistry 8(4);1459-66. PMID: 4897523

Chao70: Chao J, Graves DJ (1970). "pH dependence of the kinetic parameters of maltodextrin phosphorylase." Biochem Biophys Res Commun 40(6);1398-403. PMID: 4933689

Chen68: Chen GS, Segel IH (1968). "Purification and properties of glycogen phosphorylase from Escherichia coli." Arch Biochem Biophys 1968;127(1);175-86. PMID: 4878695

Chen68a: Chen GS, Segel IH (1968). "Escherichia coli polyglucose phosphorylases." Arch Biochem Biophys 1968;127(1);164-74. PMID: 4878694

Curtis75: Curtis SJ, Epstein W (1975). "Phosphorylation of D-glucose in Escherichia coli mutants defective in glucosephosphotransferase, mannosephosphotransferase, and glucokinase." J Bacteriol 122(3);1189-99. PMID: 1097393

DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114

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Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
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