We purified a 5.4 kDa peptide which is present in the intermediate and infectious form, but not in the reproductive form of a symbiotic bacterium Holospora obtusa of the ciliate Paramecium caudatum. Sequencing of its gene revealed that it encodes a peptide composed of 49 amino acids, and that the peptide is preceded by a putative signal peptide of 19 amino acids. We determined the transcription start point for the gene by primer extension analysis, indicating that the transcription starts with a G nucleotide located 33 nucleotides upstream from the translational initiation codon. Northern blot hybridization showed that the gene is highly expressed in the intermediate form, a transitional stage from the reproductive to infectious form of the bacterium. Immunoelectron microscopy with anti-5.4 kDa peptide antiserum revealed that the 5.4 kDa peptide is localized in the periplasm of the infectious form.
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1 February 1997
Cloning and Sequencing of Gene Coding for a Periplasmic 5.4 kDa Peptide of the Macronucleus-Specific Symbiont Holospom obtusa of the Ciliate Paramecium caudatum
Hideo Dohra,
Kazuo Yamamoto,
Masahiro Fujishima,
Hajime Ishikawa