Recombinant Legionella pneumophila 2-dehydro-3-deoxyphosphooctonate aldolase (kdsA)
Description
Introduction to Recombinant Legionella pneumophila 2-Dehydro-3-Deoxyphosphooctonate Aldolase (kdsA)
Recombinant Legionella pneumophila 2-dehydro-3-deoxyphosphooctonate aldolase (kdsA) is an engineered version of the bacterial enzyme responsible for catalyzing a critical step in the biosynthesis of lipopolysaccharide (LPS) and related carbohydrates. This enzyme belongs to the aldolase family and plays a pivotal role in the formation of 3-deoxy-D-manno-octulosonate (KDO), a key component of bacterial surface polysaccharides. In L. pneumophila, kdsA contributes to the production of legionaminic acid, a sialic acid-like molecule integral to the pathogen’s LPS and capsular polysaccharides .
Catalytic Mechanism
kdsA facilitates the stereospecific condensation of phosphoenolpyruvate (PEP) with a sugar phosphate substrate (e.g., 2,4-diacetamido-2,4,6-trideoxymannose) to form 3-deoxy-D-manno-octulosonate 8-phosphate (KDO-8-phosphate) and inorganic phosphate (P<sub>i</sub>) . This reaction proceeds via a C-O bond cleavage mechanism, requiring divalent metal ions (e.g., Mn<sup>2+</sup> or Mg<sup>2+</sup>) as cofactors .
Substrate Specificity
| Substrate | Role in Reaction | Product | Cofactor Requirement |
|---|---|---|---|
| Phosphoenolpyruvate (PEP) | Electrophilic partner | KDO-8-phosphate + P<sub>i</sub> | Mn<sup>2+</sup>, Mg<sup>2+</sup> |
| 2,4-Diacetamido-2,4,6-trideoxymannose | Nucleophilic partner | – | – |
Expression Systems and Recombinant Production
Recombinant kdsA is expressed in diverse hosts to optimize yield and post-translational modifications:
| Host System | Advantages | Challenges |
|---|---|---|
| E. coli | High yield, rapid production | Limited folding efficiency |
| Saccharomyces cerevisiae (Yeast) | Proper disulfide bonding | Lower yields than E. coli |
| Insect Cells | Native-like folding, glycosylation | Complex, costly vectors |
| Mammalian Cells | Authentic post-translational modifications | Limited scalability |
E. coli and yeast remain the most efficient systems, with yields sufficient for biochemical assays . Purification typically involves affinity chromatography (e.g., His-tagged constructs) .
Role in Lipopolysaccharide (LPS) Biosynthesis
kdsA is critical for synthesizing legionaminic acid, a component of L. pneumophila’s LPS O-antigen. This structural feature is linked to:
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Pathogen virulence: LPS modulates host immune evasion and intracellular survival .
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Antigenic diversity: Legionaminic acid contributes to serogroup-specific LPS variations .
Mechanistic Studies
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Stereochemical analysis: The L. pneumophila kdsA homologue (NeuB) employs an anti-elimination/syn-addition mechanism, distinct from sialic acid synthases .
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Metal dependency: Mn<sup>2+</sup> enhances activity, while Mg<sup>2+</sup> supports moderate catalysis .
Potential Therapeutic Targets
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Antibiotic development: Inhibiting kdsA could disrupt LPS synthesis, impairing bacterial viability .
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Vaccine design: Legionaminic acid derivatives may serve as immunogens for serogroup-specific vaccines .
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Low in vitro activity: Recombinant L. pneumophila kdsA (NeuB) shows reduced catalytic efficiency compared to homologues, necessitating optimization .
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Host-pathogen interaction: kdsA’s role in modulating host immune responses (e.g., cytokine regulation) remains understudied .
References PubMed: Multiple ecto-nucleoside triphosphate diphosphohydrolases... PMC: Virulence Properties of the Legionella Pneumophila Cell Envelope PubMed: Biosynthesis of CMP-N,N'-diacetyllegionaminic acid... PMC: Functional and biochemical characterization of a recombinant... Lifeome: Recombinant 2-dehydro-3-deoxyphosphooctonate aldolase (kdsA)... Genprice: Recombinant Legionella pneumophila kdsA product listing
Product Specs
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Note: All proteins are shipped with standard blue ice packs unless otherwise requested. Dry ice shipping requires prior communication and incurs additional charges.
Generally, liquid formulations have a 6-month shelf life at -20°C/-80°C, while lyophilized forms maintain stability for 12 months at -20°C/-80°C.
The specific tag type is determined during production. Please inform us of any tag type requirements for preferential development.
