Variation in Expression of the Haemophilus Influenzae HMW Adhesins: A Prokaryotic System Reminiscent of Eukaryotes

Expression of a number of eukaryotic genes is regulated by long stretches of tandem repeats located within the 5′untranslated region of the particular gene. In this study, we describe a regulatory system in Haemophilus influenzae with striking similarities to those found in eukaryotes. We show that...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1999-02, Vol.96 (3), p.1077-1082
Main Authors: Dawid, Suzanne, Barenkamp, Stephen J., St. Geme, Joseph W.
Format: Article
Language:English
Subjects:
Adhesins, Bacterial - genetics
Animals
Bacteria
Bacterial Proteins - genetics
Base Sequence
Biological Sciences
Chinchilla - microbiology
Genes
Genetic Variation
Haemophilus influenzae
Haemophilus influenzae - genetics
Haemophilus influenzae - isolation & purification
Humans
Infections
Insect colonies
Messenger RNA
Microbiology
Middle ear
Molecular Sequence Data
Plasmids
Polymerase Chain Reaction
Promoter regions
Promoter Regions, Genetic
Protein synthesis
Repetitive Sequences, Nucleic Acid
Respiratory diseases
RNA
RNA, Bacterial - genetics
RNA, Bacterial - isolation & purification
Sequence Deletion
Tandem repeat sequences
Transcription, Genetic
Untranslated Regions
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Summary:Expression of a number of eukaryotic genes is regulated by long stretches of tandem repeats located within the 5′untranslated region of the particular gene. In this study, we describe a regulatory system in Haemophilus influenzae with striking similarities to those found in eukaryotes. We show that expression of the HMW1 and HMW2 adhesins varies based on the number of 7-bp tandem repeats in the hmw1A and hmw2A promoters. The repeats lie between two separate transcription initiation sites and exert a repressive effect, such that increases in repeat number result in step-wise decreases in level of specific mRNA and protein production and vice versa. The range of expression of HMW1 and HMW2 varies between very weak and very strong, with a series of gradations in between. Variation in the number of repeats in the hmw1A and hmw2A promoters occurs in individual colonies passaged in vitro, in an animal model of infection, and during natural infection in humans. This system of regulation is unique in prokaryotes and likely enhances the pathogenicity of the organism by increasing adaptive potential.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.96.3.1077