| 1. |
- Goncalves, Odete Sofia Lopes, et al.
(författare)
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The repeated 36 amino acid motif of Chlamydia trachomatis Hc2 protein binds to the major groove of DNA
- 2019
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Ingår i: Research in Microbiology. - : ELSEVIER. - 0923-2508 .- 1769-7123. ; 170:6-7, s. 256-262
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Tidskriftsartikel (refereegranskat)abstract
- 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. (C) 2019 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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| 2. |
- Klint, Markus, et al.
(författare)
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Mosaic structure of intragenic repetitive elements in histone H1-like protein Hc2 varies within serovars of Chlamydia trachomatis
- 2010
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Ingår i: BMC Microbiology. - : BioMed Central. - 1471-2180. ; 10, s. 81-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The histone-like protein Hc2 binds DNA in Chlamydia trachomatis and is known to vary in size between 165 and 237 amino acids, which is caused by different numbers of lysine-rich pentamers. A more complex structure was seen in this study when sequences from 378 specimens covering the hctB gene, which encodes Hc2, were compared. RESULTS: This study shows that the size variation is due to different numbers of 36-amino acid long repetitive elements built up of five pentamers and one hexamer. Deletions and amino acid substitutions result in 14 variants of repetitive elements and these elements are combined into 22 configurations. A protein with similar structure has been described in Bordetella but was now also found in other genera, including Burkholderia, Herminiimonas, Minibacterium and Ralstonia.Sequence determination resulted in 41 hctB variants that formed four clades in phylogenetic analysis. Strains causing the eye disease trachoma and strains causing invasive lymphogranuloma venereum infections formed separate clades, while strains from urogenital infections were more heterogeneous. Three cases of recombination were identified. The size variation of Hc2 has previously been attributed to deletions of pentamers but we show that the structure is more complex with both duplication and deletions of 36-amino acid long elements. CONCLUSIONS: The polymorphisms in Hc2 need to be further investigated in experimental studies since DNA binding is essential for the unique biphasic life cycle of the Chlamydiacae. The high sequence variation in the corresponding hctB gene enables phylogenetic analysis and provides a suitable target for the genotyping of C. trachomatis.
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