Studies on Protein Synthesis in Kappa Particles

Abstract

~~~ ~~ ~~ ~ ~ Further evidence that kappa endosymbionts of stock 7 Paramecium biaurelia [ Caedibacter varicaedens] are bacteria is given by the discovery of a prokaryotic translational system in these particles. Kappa proteins incorporate 35S in in vivo experiments. However, there is no evidence that the translational systems of the host paramecia and the symbionts are shared. On the contrary, experiments with symbiont-bearing and symbiont-free strains strongly indicate that all major proteins found in kappa are synthesized in kappa. In this respect, kappa clearly differs from cell organelles. Protein synthesis in kappa is not inhibited by cycloheximide and the aminoglycoside G418, which do inhibit, although not completely, protein synthesis of the host cells. On the other hand, chloramphenicol quantitatively blocks translation in kappa without any obvious effects on the translational system of the paramecium cytoplasm.Stock 7 kappa was isolated and purified using a filter paper column. The purity of kappa preparations thus obtained was significantly improved by adding a preliminary deciliation step.