Shrimp oncoprotein nm23 is a functional nucleoside diphosphate kinase

Area of Science:

• Biochemistry
• Molecular Biology
• Aquaculture

Background:

• Nucleoside diphosphate kinase (NDK) is vital for synthesizing nucleoside triphosphates, essential for cellular energy and DNA/RNA replication.
• The Pacific whiteleg shrimp (Litopenaeus vannamei) is a globally significant aquaculture species, making its molecular mechanisms important research targets.

Purpose of the Study:

• To characterize the nucleoside diphosphate kinase (NDK) from Litopenaeus vannamei.
• To investigate the enzyme's activity, substrate affinity, and quaternary structure.
• To explore potential applications in antiviral research and understanding shrimp physiology.

Main Methods:

• Gel filtration chromatography was used to determine the quaternary structure of shrimp NDK.
• Isothermal titration calorimetry (ITC) was employed to assess the enzyme's binding affinity to deoxynucleoside diphosphates.
• Enzyme activity assays were performed to evaluate its biochemical function.

Main Results:

• Shrimp NDK was confirmed to be active and functions as a trimer.
• The enzyme exhibited micro-molar affinity for deoxyadenosine diphosphate (dADP), deoxyguanosine diphosphate (dGDP), and deoxythymidine diphosphate (dTDP).
• No detectable interaction was observed with deoxycytidine diphosphate (dCDP), similar to findings in Plasmodium falciparum NDK.

Conclusions:

• The characterization of Litopenaeus vannamei NDK provides fundamental insights into nucleotide metabolism in shrimp.
• The enzyme's properties suggest its potential utility in developing antiviral nucleotide analogs targeting white spot syndrome virus (WSSV).
• Understanding shrimp NDK is crucial for studying its role in bioenergetics, particularly under conditions like hypoxia and fasting.