S. Dawid et al., Variation in expression of the Haemophilus influenzae HMW adhesins: A prokaryotic system reminiscent of eukaryotes, P NAS US, 96(3), 1999, pp. 1077-1082
Citations number
39
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Expression of a number of eukaryotic genes is regulated by long stretches o
f tandem repeats located within the 5' untranslated region of the particula
r gene. In this study, we describe a regulatory system in Haemophilus influ
enzae 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-b
p 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
s of specific mRNA and protein production and vice versa. The range of expr
ession of HMW1 and HMW2 varies between very weak and very strong, with a se
ries of gradations in between. Variation in the number of repeats in the hm
w1A 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 path
ogenicity of the organism by increasing adaptive potential.