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Structure and Expression of a GroE‐homologous Operon of a Macronucleus‐Specific Symbiont Holospora obtusa of the Ciliate Paramecium caudatum
Author(s) -
Dohra Hideo,
Fujishima Masahiro,
Ishikawa Hajime
Publication year - 1998
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/j.1550-7408.1998.tb05072.x
Subject(s) - groel , biology , macronucleus , groes , paramecium caudatum , paramecium , immunoelectron microscopy , gene , microbiology and biotechnology , escherichia coli , open reading frame , genetics , operon , peptide sequence , antibody
The reproductive form of a macronucleus‐specific symbiont Holospora obtuse , when harbored by the macronucleus of the ciliate Paramecium caudatum , selectively synthesized a 63‐kDa protein which is immunologically related to GroEL, or HSP60, of Escherichia coli. Heat shock treatment of isolated cells of the reproductive and infectious form of the bacterium also induced the synthesis of the GroEL homolog. Immunoblotting showed that the amount of this protein per cell, whether the reproductive or infectious form, is roughly constant. Cloning and sequencing of a gene coding for the GroEL homolog suggested that the protein is 55.2% identical to GroEL of E. coli at the amino acid sequence level, and that the gene is preceded by an open reading frame which encodes a protein 39.6% identical to GroES of E. coli. Northern blot hybridization showed that the GroEL homologous gene is highly expressed in the reproductive form, but only in a trace amount in the intermediate and infectious form. Immunoelectron microscopy revealed that the GroEL homolog is localized in the cytoplasm of the reproductive and infectious form.