DIVERSITY IN THE CHLAMYDIA-TRACHOMATIS HISTONE HOMOLOG HC2

Chlamydia trachomatis elementary bodies contain two developmentally ex pressed histone H1 homologues. An 18-kDa histone homologue, Hcl, is co nserved among C. trachomatis serovars and C. psittaci. The other histo ne homologue, Hc2 (encoded by hctB), varies in size between C. trachom atis serovars but is present in reduced amounts or absent from C. psit taci. The variation in Hc2 size among C. trachomatis serovars was foun d to be due to internal deletions from a region of the hctB gene encod ing lysine- and alanine-rich pentameric repeats.