Leishmania flagellum attachment zone is critical for flagellar pocket shape, development in the sand fly, and pathogenicity in the host

Jack D Sunter,Ryuji Yanase,Ziyin Wang,Carolina Moura Costa Catta-Preta,Flavia Moreira-Leite,Jitka Myskova,Katerina Pruzinova,Petr Volf,Jeremy C Mottram,Keith Gull

doi:10.1073/pnas.1812462116

Abstract

Leishmania kinetoplastid parasites infect millions of people worldwide and have a distinct cellular architecture depending on location in the host or vector and specific pathogenicity functions. An invagination of the cell body membrane at the base of the flagellum, the flagellar pocket (FP), is an iconic kinetoplastid feature, and is central to processes that are critical for Leishmania pathogenicity. The Leishmania FP has a bulbous region posterior to the FP collar and a distal neck region where the FP membrane surrounds the flagellum more closely. The flagellum is attached to one side of the FP neck by the short flagellum attachment zone (FAZ). We addressed whether targeting the FAZ affects FP shape and its function as a platform for host-parasite interactions. Deletion of the FAZ protein, FAZ5, clearly altered FP architecture and had a modest effect in endocytosis but did not compromise cell proliferation in culture. However, FAZ5 deletion had a dramatic impact in vivo: Mutants were unable to develop late-stage infections in sand flies, and parasite burdens in mice were reduced by >97%. Our work demonstrates the importance of the FAZ for FP function and architecture. Moreover, we show that deletion of a single FAZ protein can have a large impact on parasite development and pathogenicity.

Highlights

Leishmania kinetoplastid parasites infect millions of people worldwide and have a distinct cellular architecture depending on location in the host or vector and specific pathogenicity functions
In Leishmania, the flagellum attachment zone (FAZ) is present within the flagellar pocket (FP) neck, and we hypothesized that the FAZ would have an important role in defining and maintaining FP shape
The overall organization and morphology of the FAZ5 null mutant appeared normal by light microscopy (Fig. 1B); the SMP1 signal within the FP was shorter, with a reduction in the distance between the kinetoplast and the anterior cell tip, which corresponds to FP length (Fig. 1C)

Summary

Introduction

Leishmania kinetoplastid parasites infect millions of people worldwide and have a distinct cellular architecture depending on location in the host or vector and specific pathogenicity functions. Within the mammalian host, Leishmania is an intracellular parasite that infects the macrophage and adopts an amastigote morphology, with a small rounded cell body and a flagellum that barely extends beyond the cell body. In both the promastigote and amastigote forms, there is an invagination of the plasma membrane at the base of the flagellum called the flagellar pocket (FP) [3].

Methods

Results

Conclusion