Abstract
Two DNA-binding proteins with similarity to eukaryotic histone H1 have been described in Chlamydia trachomatis. In addition to the 18-kDa histone H1 homolog Hc1, elementary bodies of C. trachomatis possess an antigenically related histone H1 homolog, which we have termed Hc2, that varies in apparent molecular mass among strains. We report the molecular cloning, expression, and nucleotide sequence of the hctB gene encoding Hc2 and present evidence for in vivo DNA-binding activity of the expressed product. Expression of Hc2 in Escherichia coli induces a compaction of bacterial chromatin that is distinct from that observed upon Hc1 expression. Moreover, isolated nucleoids from Hc2-expressing E. coli exhibit markedly reduced sensitivity to DNase I. These properties of Hc2 are consistent with a postulated role in establishing the nucleoid structure of elementary bodies.
MeSH terms
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Amino Acid Sequence
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Bacterial Proteins*
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Base Sequence
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Blotting, Southern
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Chlamydia trachomatis / genetics*
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Chlamydia trachomatis / metabolism*
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Cloning, Molecular / methods
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DNA, Bacterial / genetics
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DNA-Binding Proteins / biosynthesis
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / isolation & purification
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Deoxyribonuclease I
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Escherichia coli / genetics
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Escherichia coli / ultrastructure
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Gene Expression*
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Genes, Bacterial*
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Genetic Variation
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Genomic Library
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HeLa Cells
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Histones / biosynthesis
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Histones / genetics*
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Histones / isolation & purification
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Humans
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Microscopy, Electron
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Molecular Sequence Data
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Oligodeoxyribonucleotides
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RNA, Bacterial / isolation & purification
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RNA, Bacterial / metabolism
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Restriction Mapping
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Sequence Deletion
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Sequence Homology, Amino Acid
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Transcription, Genetic
Substances
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Bacterial Proteins
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DNA, Bacterial
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DNA-Binding Proteins
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HctB protein, Chlamydia trachomatis
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Histones
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Oligodeoxyribonucleotides
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RNA, Bacterial
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Deoxyribonuclease I