Differences in mitochondrial NADH dehydrogenase activities in trypanosomatids.

Area of Science:

• Mitochondrial biology
• Parasitology
• Biochemistry

Background:

• Complex I (NADH dehydrogenase) is crucial for cellular respiration, catalyzing electron transfer and proton pumping.
• Its characterization in diverse trypanosomatid species is essential for understanding their bioenergetics.

Purpose of the Study:

• To characterize NADH dehydrogenase activity in seven monoxenous trypanosomatid species.
• To investigate the subunit composition of Complex I in Phytomonas serpens.
• To identify novel subunits, particularly those encoded by mitochondrial DNA.

Main Methods:

• Enzyme activity assays for NADH dehydrogenase.
• Mass spectrometry-based proteomics to determine subunit composition.
• Comparative analysis across multiple trypanosomatid species.

Main Results:

• Complex I activity was confirmed in Phytomonas serpens, Novymonas esmeraldas, and Sergeia podlipaevi.
• Mass spectrometry identified 24-32 subunits of Complex I in individual species.
• Several mitochondrial DNA-encoded proteins were identified as Complex I subunits for the first time.

Conclusions:

• Complex I is functionally active in specific trypanosomatid lineages, with varying subunit compositions.
• The identification of mitochondrial DNA-encoded subunits provides new insights into Complex I evolution in these parasites.
• This study expands the understanding of respiratory chain diversity in kinetoplastids.