Proteomic analysis of Giardia lamblia and Trichomonas vaginalis flagella reveal unique post‐translational modifications in tubulin that provide clues to regulation of their motilities

Abstract

All eukaryotic flagella are made of microtubules and driven by dynein motor proteins. However, every organism is unique in terms of its flagellar waveform, beat frequency, and its general motility pattern. With recent research, it is becoming clear that despite overall conservation in flagellar structure, the pattern of tubulin post‐translational modifications within the flagella are diverse and may contribute to variations in their patterns of motility. In this study, we have analyzed the tubulin post‐translational modification in the protozoan parasites Giardia lamblia and Trichomonas vaginalis using global, untargeted mass spectrometry. We show that tubulin monoglycylation is a modification localized to the flagella present in G. lamblia but absent in T. vaginalis. We also show the presence of glutamylated tubulin in both G. lamblia and T. vaginalis. Using MS/MS, we were also able to identify the previously unknown sites of monoglycylation in β‐tubulin at E438 and E439 in G. lamblia. Using isolated flagella, we also characterized the flagellar proteome in G. lamblia and T. vaginalis and identified 475 proteins in G. lamblia and 386 proteins in T. vaginalis flagella. Altogether, the flagellar proteomes as well as the sites of tubulin PTMs in these organisms, reveal potential mechanisms in regulating flagellar motilities in these neglected protozoan parasites.

Nanoscale dihydroartemisinin@zeolitic imidazolate frameworks for enhanced antigiardial activity and mechanism analysis

“…Cytoskeleton proteins of Giardia are closely related to its pathogenicity. The α-tubulin and β-tubulin could form heterodimers, the two main types of tubulin-forming microtubules ( 36 ). Microfilaments in the cytoskeleton related to encystation are formed by actin, which is part of the globular multifunctional protein family ( 37 ).…”

The Pathogenesis of Giardia Intestinalis

“…In summary, Giardia intestinalis can cause host diarrhoea through mechanisms such as shortening of the microvillous brush border, causing indigestion and impaired absorption, increased intestinal transit rate and excessive anion secretion [21]. These mechanisms are closely related to Giardiamediated caspase-dependent cellular regulation and disruption of intestinal epithelial tight junctions.…”

Application of Proteomics to the Study of the Therapeutics and Pathogenicity of Giardia duodenalis

“…Future proteomic studies on G. duodenalis may also focus on investigating the post-transcriptional regulation of this parasite, especially on translational inhibition relating to Giardia ’s Pumilio homology proteins (Puf), which may have a crucial role in the encystation of this parasite [ 68 ]. With the completion of a comprehensive molecular map of histone modifications in Giardia by Emery-Corbin et al (2021) [ 64 ], chromatin proteomics may achieve the mapping of previously reported non-histone proteins, such as tubulin [ 69 ] and cyclin B [ 70 ], by using quantitative MS profiling to confirm their dynamic variations in regulation during parasite development. Ideally, proteomics research should be linked with experimental approaches to move beyond protein identification and progress to the in vitro or in vivo investigation of these proteins as players in pathogenesis, virulence, and metabolism, and later to the validation of their role as biomarkers or drug and vaccine targets that can lead to new tools with which to control giardiasis.…”