Surface proteins of the gram-negative bacterium Holospora obtusa bind to macronuclear proteins of its host Paramecium caudatum

Abstract

Summary Holospora obtusa is a gram-negative bacterium living inside the macronucleus of the ciliate Paramecium caudatum . The bacteria leave the food vacuole after having been ingested, are transported through the cytoplasm, enter the nucleus, and start dividing. In order to analyze protein-protein interactions in the infection process, bacterial and macronuclear proteins were isolated. Binding of labeled macronuclear proteins was observed on semi-thin sections of bacteria. Using an overlay technique, blotted bacterial proteins were incubated with labeled host proteins and two bacterial proteins were found binding to nuclear proteins.