Microorganisms experience a wide variety of
fluctuating conditions caused by changes in
their surroundings or by shifting metabolic
demands. Cells must be able to quantify these
changes and concordantly alter expression
of gene subsets in a measured manner. A
great variety of mechanisms for controlling
expression in response to extracellular and
intracellular conditions have been identified
(66).Mostwell-characterized among these are
the numerous proteins that exert regulatory
control over transcription initiation (9). The
large-scale sequencing of bacterial genomes
has led to the identification of hundreds of