INTERACTION OF THE CHLAMYDIA-TRACHOMATIS HISTONE H1-LIKE PROTEIN (HC1) WITH DNA AND RNA CAUSES REPRESSION OF TRANSCRIPTION AND TRANSLATION IN-VITRO

The 18kDa histone H1-like protein from Chlamydia trachomatis (Hc1) is a RNA-binding protein thought to be involved in condensation of the ch lamydial chromosome during late stages in the chlamydial life cycle. E xpression of Hc1 in Escherichia coil results in an overall relaxation of DNA and severely affects DNA, RNA and protein synthesis. We have an alysed the interaction of Hc1 with single-stranded DNA and RNA by Sout hwestern and Northwestern blotting. Furthermore, we show that purified , recombinant Hc1 dramatically affects transcription and translation i n vitro at physiologically relevant concentrations. These results were found to coincide with the formation of condensed Hc1-DNA and Hc1-RNA complexes as revealed by agarose gel electrophoresis and electron mic roscopy. The implications of these results for possible functions of H c1 in vivo are discussed.