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PMID:19304823
| Citation |
Lindner, SN, Knebel, S, Wesseling, H, Schoberth, SM and Wendisch, VF (2009) Exopolyphosphatases PPX1 and PPX2 from Corynebacterium glutamicum. Appl. Environ. Microbiol. 75:3161-70 |
|---|---|
| Abstract |
Corynebacterium glutamicum accumulates up to 300 mM of inorganic polyphosphate (PolyP) in the cytosol or in granules. The gene products of cg0488 (ppx1) and cg1115 (ppx2) were shown to be active as exopolyphosphatases (PPX), as overexpression of either gene resulted in higher exopolyphosphatase activities in crude extracts and deletion of either gene with lower activities than those of the wild-type strain. PPX1 and PPX2 from C. glutamicum share only 25% identical amino acids and belong to different protein groups, which are distinct from enterobacterial, archaeal, and yeast exopolyphosphatases. In comparison to that in the wild type, more intracellular PolyP accumulated in the Deltappx1 and Deltappx2 deletion mutations but less when either ppx1 or ppx2 was overexpressed. When C. glutamicum was shifted from phosphate-rich to phosphate-limiting conditions, a growth advantage of the deletion mutants and a growth disadvantage of the overexpression strains compared to the wild type were observed. Growth experiments, exopolyphosphatase activities, and intracellular PolyP concentrations revealed PPX2 as being a major exopolyphosphatase from C. glutamicum. PPX2(His) was purified to homogeneity and shown to be active as a monomer. The enzyme required Mg2+ or Mn2+ cations but was inhibited by millimolar concentrations of Mg2+, Mn2+, and Ca2+. PPX2 from C. glutamicum was active with short-chain polyphosphates, even accepting pyrophosphate, and was inhibited by nucleoside triphosphates. |
| Links |
PubMed PMC2681651 Online version:10.1128/AEM.02705-08 |
| Keywords |
Acid Anhydride Hydrolases/genetics; Acid Anhydride Hydrolases/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Calcium/pharmacology; Corynebacterium glutamicum/chemistry; Corynebacterium glutamicum/enzymology; Corynebacterium glutamicum/growth & development; Enzyme Activators/pharmacology; Gene Deletion; Gene Dosage; Magnesium/pharmacology; Manganese/pharmacology; Phylogeny; Polyphosphates/metabolism; Sequence Homology, Amino Acid |
Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
| GO:0004309: exopolyphosphatase activity |
ECO:0000315: |
F |
The deletion of ppx1 and ppx2 in C. glutamicum resulted in the decrease of exopolyphosphatase activity. Figure 1 shows that there was an accumulation of cellular PolyP mutated C. glutamicum cells versus wild type. This shows that the exopolyphosphatase protein serves as a regulatory protein of cellular PolyP |
complete | ||||
| GO:0004309: exopolyphosphatase activity |
ECO:0000314: |
F |
Different amounts of PolyPs were added in chains in the medium containing the PPX2His (exopolyphosphatase with a His tag) to see if an increase in the length of the PolyP chain increased the activity if the PPX2 activity. According to the results in Figure 3, the increase in the length (from short to medium) increased the percent of activity. Therefore, the enzyme activity depends on the amount of cellular PolyP available. |
complete | ||||
Notes
See also
References
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