A novel chromatin-forming histone H1 homologue is encoded by a dispensable and growth-regulated gene in Bordetella pertussis.
We report the identification of a protein homologous to a histone H1 in Bordetella pertussis. The B. pertussis histone homologue, BpH1, varies in size in different strains from 182 to 206 amino acids. The variability of the size of the protein is due to gene variability by insertion or deletion of DNA modules. Insertion of a kanamycin cassette into the bpH1 gene generates a BpH1 null mutant with phenotypic properties and growth rate similar to those of the wild-type strain, showing that this gene is dispensable. In vitro, the BpH1 protein prevents chromosomal DNA degradation from DNase I and constrains supercoiled DNA. Transcription of the bpH1 gene is activated during exponential growth of the bacteria, whereas it is repressed during the stationary phase of growth. It is proposed that BpH1 plays a role in chromatin formation and condensation during DNA replication and that repression of transcription depends upon a reduced rate of DNA replication.
Scarlato
V
V
Immunobiological Research Institute Siena (IRIS), Siena, Italy.
Aricò
B
B
Goyard
S
S
Ricci
S
S
Manetti
R
R
Prugnola
A
A
Manetti
R
R
Polverino-De-Laureto
P
P
Ullmann
A
A
Rappuoli
R
R
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D005075:Biological Evolution; D001886:Bordetella pertussis / Q000235:genetics* / Q000254:growth & development; D002843:Chromatin / Q000378:metabolism*; D016384:Consensus Sequence; D004269:DNA, Bacterial / Q000378:metabolism; D004278:DNA, Superhelical / Q000235:genetics; D003850:Deoxyribonuclease I / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D006657:Histones / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D007612:Kanamycin / Q000494:pharmacology; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D012045:Regulatory Sequences, Nucleic Acid; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D002843:Chromatin; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D006657:Histones; D009687:Nuclear Proteins; C094332:bpH1 protein, Bordetella pertussis; D007612:Kanamycin; D003850:Deoxyribonuclease I; D015719:Single-Strand Specific DNA and RNA Endonucleases