THE ROLE OF THE FLAGELLUM ATTACHMENT ZONE IN THE ORGANIZATION OF THE MICROTUBULE CYTOSKELETON OF TRYPANOSOMA BRUCEI

Abstract

THE MICROTUBULE CYTOSKELETON FORMS THE MOST PROMINENT STRUCTURAL SYSTEM IN TRYPANOSOMA BRUCEI, UNDERGOING EXTENSIVE MODIFICATIONS DURING THE CELL CYCLE. VISUALIZATION OF TYROSINATED MICROTUBULES LEADS TO A SEMICONSERVATIVE MODE OF INHERITANCE, WHEREAS RECENT STUDIES EMPLOYING MICROTUBULE PLUS END TRACKING PROTEINS HAVE HINTED AT AN ASYMMETRIC INHERITANCE. TO FURTHER THIS KNOWLEDGE, THE DYNAMICS OF THE MICROTUBULE CYTOSKELETON WAS VISUALIZED BY INDUCIBLE YFP-α-TUBULIN EXPRESSION. DURING NEW FLAGELLUM/FLAGELLUM ATTACHMENT ZONE (FAZ) BIOGENESIS AND CELL GROWTH, YFP-α-TUBULIN WAS INCORPORATED MAINLY BETWEEN THE OLD AND NEW FLAGELLUM/FAZ COMPLEXES. CYTOSKELETAL MODIFICATIONS AT THE POSTERIOR END OF THE CELLS WERE OBSERVED WITH EB1, A MICROTUBULE PLUS END BINDING PROTEIN, PARTICULARLY DURING MITOSIS. ADDITIONALLY, THE NEWLY FORMED MICROTUBULES SEGREGATED ASYMMETRICALLY, WITH THE DAUGHTER CELL INHERITING THE NEW FLAGELLUM/FAZ COMPLEX RETAINING MOST OF THE NEW MICROTUBULES. TOGETHER,