Related Experiment Video
Updated: Jul 14, 2026
08:25
Genetic Modification of Cyanobacteria by Conjugation Using the CyanoGate Modular Cloning Toolkit
Published on: October 31, 2019
NCgl2620 encodes a class II polyphosphate kinase in Corynebacterium glutamicum
Steffen N Lindner1, Dolores Vidaurre, Sabine Willbold
1Institute of Molecular Microbiology and Biotechnology, Westfalian Wilhelms University Muenster, Correnstr. 3, Muenster, Germany.
Applied and Environmental Microbiology
|June 5, 2007
Summary
Corynebacterium glutamicum synthesizes polyphosphate (poly P) using a class II enzyme, PPK2B. This enzyme is crucial for poly P accumulation and bacterial growth under phosphate-limiting conditions.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Corynebacterium glutamicum accumulates significant amounts of polyphosphate (poly P), a polymer of phosphate residues, up to 600 mM.
- Poly P granules, also known as volutin, can occupy up to 37% of the cell volume.
- The bacterium lacks the canonical class I polyphosphate kinase (PPK1) but possesses two genes for putative class II polyphosphate kinases (PPK2): ppk2A and ppk2B.
Purpose of the Study:
- To investigate the role of putative class II polyphosphate kinases (PPK2A and PPK2B) in polyphosphate synthesis in Corynebacterium glutamicum.
- To characterize the enzymatic activity and kinetic properties of the identified PPK2B enzyme.
Main Methods:
- Gene deletion and overexpression of ppk2A and ppk2B.
- Assay of polyphosphate kinase (PPK) activity.
- Measurement of cellular poly P content.
- Purification and characterization of PPK2B using (31)P nuclear magnetic resonance.
- Growth analysis of deletion mutants under varying phosphate conditions.
Main Results:
- Deletion of ppk2B significantly decreased PPK activity and cellular poly P content, while its overexpression increased both.
- ppk2A deletion or overexpression did not significantly alter PPK activity or poly P content.
- Purified PPK2B functions as an active homotetramer, synthesizing poly P with an average chain length of approximately 125.
- (31)P nuclear magnetic resonance confirmed the poly P chain length.
- PPK2B exhibited higher catalytic efficiency in poly P synthesis compared to nucleoside triphosphate formation from poly P.
- The ppk2B deletion mutant showed a growth defect under phosphate-limiting conditions, despite normal growth under phosphate-sufficient conditions.
Conclusions:
- PPK2B is the primary class II polyphosphate kinase responsible for poly P synthesis in Corynebacterium glutamicum.
- PPK2B plays a critical role in cellular poly P accumulation and is essential for growth under phosphate-limiting conditions.
- The enzymatic properties of PPK2B suggest its primary role in poly P formation rather than degradation.
Related Concept Videos
01:58Cell Specific Gene Expression
Multicellular organisms contain a variety of structurally and functionally distinct cell types, but the DNA in all the cells originated from the same parent cells. The differences in the cells can be attributed to the differential gene expression. Liver cells, whose functions include detoxification of blood, production of bile to metabolize fats, and synthesis of proteins essential for metabolism, must express a specific set of genes to perform their functions. Gene expression also varies with...
01:25cAMP-dependent Protein Kinase Pathways
Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
01:09GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
01:28Plasmids
Plasmids are extrachromosomal DNA molecules found in bacteria, archaea, and some eukaryotic microbes like yeast. These small, circular DNA structures typically contain fewer than 30 genes, although some may exist linearly. Plasmids vary in their number within a cell, known as copy number. Single-copy plasmids are present in one copy per cell and multi-copy plasmids are present in multiple copies, reaching over 100 copies per cell.Plasmids usually replicate independently of the chromosomal DNA...
01:17Gram-negative Bacterial Protein Secretion Systems
Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...