Characterization of Primitive Formins from Leishmania major

Dileep, Drisya (2016) Characterization of Primitive Formins from Leishmania major. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Leishmania major is a protozoan parasite responsible for a complex group of diverse diseases collectively known as leishmaniases. A dynamic actin cytoskeleton is required for endocytosis, exocytosis and cell division that are essential for its survival and effective pathogenesis. For actin filaments dynamics multiple actin binding proteins are involved. Formins are one of the key actin nucleators that regulate actin dynamic in vivo. Formins are eukaryotic innovation and the first appearance of formins can be seen in this primitive organism. Leishmania major has two putative formins; Formin A and Formin B. In this study, we tried to characterize these primitive formins which will give insight into how primitive formins would have behaved. Our results show that FH2 domain containing c-terminal fragment/region of formin A and Formin B could bind with actin purified from rabbit muscle but could not bundle actin in vitro. Both the formin A and Formin B inhibit actin filament polymerization, and acts as G-actin sequestering protein. Results from further investigation indicated Formin A inhibit elongation of actin filament may act as an actin filaments capping protein, while Formin B did not inhibit nor enhance the actin filament elongation rate. From all these observations we come to the conclusion that both formins act differently; Formin A may be acting as an actin capping protein while Formin B may act as a G-actin-sequestering protein. Interestingly, there is no actin capping protein in Leishmania major so far reported. Further investigation is needed to show that Formin A may serve as actin filament capping protein for Leishmania major.

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