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Title: The Repetitive Cytoskeletal Protein H49 of Trypanosoma cruzi Is a Calpain-Like Protein Located at the Flagellum Attachment Zone
Authors: Galetovic, Alexandra [UNIFESP]
Souza, Renata T. [UNIFESP]
Santos, Marcia R. M.
Cordero, Esteban Mauricio [UNIFESP]
Bastos, Izabela M. D.
Santana, Jaime M.
Ruiz, Jeronimo C.
Lima, Fabio M. [UNIFESP]
Marini, Marjorie Mendes [UNIFESP]
Mortara, Renato Arruda [UNIFESP]
Silveira, Jose Franco da [UNIFESP]
Universidade Federal de São Paulo (UNIFESP)
Univ Antofagasta
Univ Bandeirante São Paulo
Universidade de Brasília (UnB)
Fiocruz MS
Issue Date: 11-Nov-2011
Publisher: Public Library Science
Citation: Plos One. San Francisco: Public Library Science, v. 6, n. 11, 12 p., 2011.
Abstract: Background: Trypanosoma cruzi has a single flagellum attached to the cell body by a network of specialized cytoskeletal and membranous connections called the flagellum attachment zone. Previously, we isolated a DNA fragment (clone H49) which encodes tandemly arranged repeats of 68 amino acids associated with a high molecular weight cytoskeletal protein. in the current study, the genomic complexity of H49 and its relationships to the T. cruzi calpain-like cysteine peptidase family, comprising active calpains and calpain-like proteins, is addressed. Immunofluorescence analysis and biochemical fractionation were used to demonstrate the cellular location of H49 proteins.Methods and Findings: All of H49 repeats are associated with calpain-like sequences. Sequence analysis demonstrated that this protein, now termed H49/calpain, consists of an amino-terminal catalytic cysteine protease domain II, followed by a large region of 68-amino acid repeats tandemly arranged and a carboxy-terminal segment carrying the protease domains II and III. the H49/calpains can be classified as calpain-like proteins as the cysteine protease catalytic triad has been partially conserved in these proteins. the H49/calpains repeats share less than 60% identity with other calpain-like proteins in Leishmania and T. brucei, and there is no immunological cross reaction among them. It is suggested that the expansion of H49/calpain repeats only occurred in T. cruzi after separation of a T. cruzi ancestor from other trypanosomatid lineages. Immunofluorescence and immunoblotting experiments demonstrated that H49/calpain is located along the flagellum attachment zone adjacent to the cell body.Conclusions: H49/calpain contains large central region composed of 68-amino acid repeats tandemly arranged. They can be classified as calpain-like proteins as the cysteine protease catalytic triad is partially conserved in these proteins. H49/calpains could have a structural role, namely that of ensuring that the cell body remains attached to the flagellum by connecting the subpellicular microtubule array to it.
ISSN: 1932-6203
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