A core UPS molecular complement implicates unique endocytic compartments at the parasite-host interface in Giardia lamblia.

Balmer, Erina A; Wirdnam, Corina D; Faso, Carmen (2023). A core UPS molecular complement implicates unique endocytic compartments at the parasite-host interface in Giardia lamblia. Virulence, 14(1), p. 2174288. Taylor & Francis 10.1080/21505594.2023.2174288

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Unconventional protein secretion (UPS) plays important roles in cell physiology. In contrast to canonical secretory routes, UPS does not generally require secretory signal sequences and often bypasses secretory compartments such as the ER and the Golgi apparatus.Giardia lamblia is a protist parasite with reduced subcellular complexity which releases several proteins, some of them virulence factors, without canonical secretory signals. This implicates UPS at the parasite-host interface. No dedicated machinery nor mechanism(s) for UPS in Giardia are currently known, although speculations on the involvement of endocytic organelles called PV/PECs, have been put forth.To begin to address the question of whether PV/PECs are implicated in virulence-associated UPS and to define the composition of molecular machinery involved in protein release, we employed affinity purification and mass spectrometry, coupled to microscopy-based subcellular localization and signal correlation quantification to investigate the interactomes of 11 reported unconventionally-secreted proteins, all predicted to be cytosolic. A subset of these associates to PV/PECs. Extended and validated interactomes point to a core PV/PECs-associated UPS machinery, which includes uncharacterized and Giardia-specific coiled-coil proteins and NEK kinases. Finally, a subset of the alpha-giardin protein family was enriched in all PV/PECs-associated protein interactomes, highlighting a previously unappreciated role for these proteins at PV/PECs and in UPS.Taken together, our results provide the first characterization of a virulence-associated UPS protein complex in Giardia lamblia at PV/PECs, suggesting a novel link between these primarily endocytic and feeding organelles and UPS at the parasite-host interface.

Item Type:

Journal Article (Original Article)


05 Veterinary Medicine > Other Institutions > Centers Vetsuisse Faculty > Multidisciplinary Center for Infectious Diseases (MCID)
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Cell Biology

Graduate School:

Graduate School for Cellular and Biomedical Sciences (GCB)

UniBE Contributor:

Balmer, Erina Alexandra, Wirdnam, Corina-Daniela, Faso, Carmen


500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health




Taylor & Francis




Pubmed Import

Date Deposited:

03 Feb 2023 09:59

Last Modified:

14 Feb 2023 00:16

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

Giardia lamblia interactome peripheral endocytic compartments unconventional protein secretion virulence





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