Subsystem: D-allose utilization

This subsystem's description is:

Escherichia coli K-12 can utilize D-allose, an all-cis hexose, as a sole carbon source. The operon responsible for D-allose metabolism consists of six genes, alsRBACEK, which are inducible by D-allose and are under the control of the repressor gene alsR. This operon is also subject to catabolite repression.
Three genes, alsB, alsA, and alsC, appear to be necessary for transport of D-allose. D-Allose-binding protein, encoded by alsB, is a periplasmic protein that has an affinity for D-allose.As was found for other binding-protein-mediated ABC transporters, the allose transport system includes an ATP-binding component (AlsA) and a transmembrane protein (AlsC). It was found that AlsE (a putative D-allulose-6-phosphate 3-epimerase), but not AlsK (a putative D-allose kinase), is necessary for allose metabolism. During the study in ref.2, it was observed that the D-allose transporter is partially responsible for the low-affinity transport of D-ribose.

========Variant codes:====================

1.0 - classical pathway of D-allose utilization is complete: operon of six genes - alsRBACEK, with D-allose ABC transporter and D-allose kinase (EC 2.7.1.55);

2.0 - D-allose uptake and phosphorilation by D-allose-specific PTS system (see subset *PTSIIBCA), no AlsK- D-allose kinase (EC 2.7.1.55), as in all Listeria.

For more information, please check out the description and the additional notes tabs, below

Literature ReferencesThe D-allose operon of Escherichia coli K-12. Kim C Journal of bacteriology 1997 Dec9401019
D-Allose catabolism of Escherichia coli: involvement of alsI and regulation of als regulon expression by allose and ribose. Poulsen TS Journal of bacteriology 1999 Nov10559180
DiagramFunctional RolesSubsystem SpreadsheetDescriptionAdditional Notes 

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AlsKA6PI*AlsE*AlsBAC*PTSIIBCA*AlsR
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Escherichia coli K-12 can utilize D-allose, an all-cis hexose, as a sole carbon source. The operon responsible for D-allose metabolism consists of six genes, alsRBACEK, which are inducible by D-allose and are under the control of the repressor gene alsR. This operon is also subject to catabolite repression.
Three genes, alsB, alsA, and alsC, appear to be necessary for transport of D-allose. D-Allose-binding protein, encoded by alsB, is a periplasmic protein that has an affinity for D-allose.As was found for other binding-protein-mediated ABC transporters, the allose transport system includes an ATP-binding component (AlsA) and a transmembrane protein (AlsC). It was found that AlsE (a putative D-allulose-6-phosphate 3-epimerase), but not AlsK (a putative D-allose kinase), is necessary for allose metabolism. During the study in ref.2, it was observed that the D-allose transporter is partially responsible for the low-affinity transport of D-ribose.

========Variant codes:====================

1.0 - classical pathway of D-allose utilization is complete: operon of six genes - alsRBACEK, with D-allose ABC transporter and D-allose kinase (EC 2.7.1.55);

2.0 - D-allose uptake and phosphorilation by D-allose-specific PTS system (see subset *PTSIIBCA), no AlsK- D-allose kinase (EC 2.7.1.55), as in all Listeria.
This subsystem was originally encoded by master:laikova.
Ownership of the SS was changed 11/08/07 to OlgaZ for extending and further maintenance.

===============OVERVIEW:===========================================

Genes involved in allose utilization of Escherichia coli K-12 are organized in at least two operons, alsRBACE and alsI, located next to each other on the chromosome but divergently transcribed.

It was shown that AlsE (epimerase) is essential, although AlsK (kinase) and RpiB (isomerase) are dispensable for D-allose utilization. In A. aerogenes, it was shown that D-allose kinase and D-allose-6-phosphate isomerase activities are required.


*******From Ref.2:**********

It is not surprising that allose and ribose transport systems are functionally redundant because D-ribose exists primarily as a pyranose form (80%) in solution, which is presumably responsible for interacting with the periplasmic binding protein and also with the membrane components. This configuration of D-ribose is structurally analogous to that of D-allose.
Moreover, D-ribose can still be utilized when both the ribose and allose systems are absent , suggesting that other structurally related permeases provide the remaining activity of low-affinity transport.

========REFERENCES:==========

1. Poulsen TS, Chang YY, Hove-Jensen B. D-Allose catabolism of Escherichia coli: involvement of alsI and regulation of als regulon expression by allose and ribose.J Bacteriol. 1999 Nov;181(22):7126-30. PMID: 10559180

2. Kim C, Song S, Park C. The D-allose operon of Escherichia coli K-12.
J Bacteriol. 1997 Dec;179(24):7631-7. PMID: 9401019