The repeated 36 amino acid motif of Chlamydia trachomatis Hc2 protein binds to the major groove of DNA

Odete Sofia Lopes Gonçalves, Gunna Christiansen, Arne Holm, Bjørn Herrmann, Markus Klintstedt, Steffen B Petersen, Svend Birkelund

Research output: Contribution to journalJournal articleResearchpeer-review


The gram-negative, obligate intracellular human pathogen, Chlamydia trachomatis has a bi-phasic developmental cycle. The histone H1-like C. trachomatis DNA binding protein, Hc2, is produced late during the developmental cycle when the dividing reticulate body transforms into the smaller, metabolically inactive elementary body. Together with Hc1, the two proteins compact the chlamydial chromosome and arrest replication and transcription. Hc2 is heterogeneous in length due to variation in the number of lysine rich pentamers. Six pentamers and one hexamer constitute a 36 amino acid long repetitive unit that, in spite of variations, is unique for Chlamydiaceae. Using synthetic peptides, the DNA-binding capacity of the 36 amino acid peptide and that of a randomized peptide was analyzed. Both peptides bound and compacted plasmid DNA, however, electron microscopy of peptide/DNA complexes showed major differences in the resulting aggregated structures. Fluorescence spectroscopy was used to analyze the binding. After complexing plasmid DNA with each of three different intercalating dyes, increasing amounts of peptides were added and fluorescence spectroscopy performed. The major groove binder, methyl green, was displaced by both peptides at low concentrations, while the minor groove binder, Hoechts, and the intercalating dye, Ethidium Bromide, were displaced only at high concentrations of peptides.

Original languageEnglish
JournalResearch in Microbiology
Issue number6-7
Pages (from-to)256-262
Number of pages7
Publication statusPublished - 1 Sep 2019

Bibliographical note

Copyright © 2019 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.


  • Chlamydia trachomatis
  • DNA packing
  • Fluorescence spectroscopy
  • Hc2
  • Histone H1-like protein
  • Methyl green

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