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Protein phosphorylation by intact Babesia bovis
Abstract:
Babesia bovis rapidly incorporated [32P]orthophosphate into more than 30 polypeptide chains, the majority of which appeared to be membrane or particle bound. Phosphorylation occurred more rapidly in free parasites than in parasitized erythrocytes, suggesting the acceptor polypeptides were either babesial in origin or erythrocyte proteins were intimately associated with the parasite. Some characteristics of the phosphorylation system are described. The phosphorylation was little affected by dibutyryl cAMP or dibutyryl cGMP but was strongly inhibited by the calcium ionophore A23187, which also inhibited protein synthesis. Two dimensional electrophoresis of B. bovis extracts after pulse labelling with [35S]methionine or [32P]orthophosphate showed that all polypeptides phosphorylated in a 30 min period were also at least partially synthesized de novo within that period, suggesting that the phosphorylated species were babesial in origin.
Insights
Babesia bovis rapidly phosphorylates over 30 proteins, primarily membrane-bound. This phosphorylation process, crucial for parasite function, is inhibited by calcium ionophore A23187.
Area of Science:
- Parasitology
- Molecular Biology
- Biochemistry
Background:
- Babesia bovis is an intraerythrocytic parasite causing significant economic losses in cattle.
- Understanding the molecular mechanisms of Babesia bovis, particularly protein phosphorylation, is crucial for developing control strategies.
Purpose of the Study:
- To investigate the protein phosphorylation patterns in Babesia bovis.
- To characterize the phosphorylation system and identify the origin of phosphorylated proteins.
Main Methods:
- Babesia bovis parasites were labeled with [32P]orthophosphate and [35S]methionine.
- Two-dimensional electrophoresis was used to analyze protein phosphorylation.
- The effect of cyclic nucleotides and calcium ionophore A23187 on phosphorylation was assessed.
Main Results:
- Babesia bovis rapidly incorporated [32P]orthophosphate into over 30 polypeptide chains, predominantly membrane or particle-bound.
- Phosphorylation occurred more rapidly in free parasites compared to parasitized erythrocytes.
- The calcium ionophore A23187 strongly inhibited phosphorylation and protein synthesis, while cAMP and cGMP had minimal effects.
- Phosphorylated polypeptides were synthesized de novo within the parasite, indicating they were of babesial origin.
Conclusions:
- Babesia bovis possesses a robust protein phosphorylation system, likely essential for its survival and virulence.
- The study identified babesial-derived proteins as the primary targets of phosphorylation.
- Calcium signaling may play a critical role in regulating Babesia bovis protein synthesis and phosphorylation.