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Role of the Cytosolic Heat Shock Protein 70 Ssa5 in the Ciliate Protozoan Tetrahymena thermophila
Author(s) -
Fukuda Yasuhiro,
Akematsu Takahiko,
Attiq Rizwan,
Tada Chika,
Nakai Yutaka,
Pearlman Ronald E.
Publication year - 2015
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/jeu.12203
Subject(s) - biology , tetrahymena , pronucleus , heterokaryon , microbiology and biotechnology , somatic cell , ciliate , heat shock protein , hsp70 , zygote , genetics , chaperone (clinical) , macronucleus , gene , embryogenesis , medicine , embryo , pathology , mutant
Heat shock protein 70 (Hsp70) is a member of a family of conserved chaperone proteins whose function is well investigated in many model organisms. Here we focus on an Hsp70 called Ssa5 in the ciliate protozoan Tetrahymena thermophila , and reveal that its translation is heat inducible as for general Hsps. Moreover, the protein is abundantly expressed in the cytoplasm during sexual reproduction (conjugation) as well as in response to heat‐stress. Knocking out of SSA 5 ( Δ SSA 5 ) does not affect the survival of the cell under heat‐stress, likely due to other Hsp70 paralogs compensating for the defect. During conjugation, Δ SSA 5 leads to a fertilization defect in which the two pronuclei are in close proximity but never fuse. The unfertilized pronuclei differentiate, resulting in a heterokaryon with developed haploid germline and somatic nuclei. In addition, degeneration of the parental somatic nucleus is not affected. These results suggest a specific involvement of Ssa5 in pronuclear fusion and fertilization.