Biology Reference
In-Depth Information
ABBREVIATIONS
Bhr-DGC
haemerythrin-coupled diguanylate cyclase
c-di-GMP
cyclic dimeric - (3
0
-5
0
)-GMP
CooA
carbon monoxide oxidation activator
DGC
diguanylate cyclase
Dos
direct oxygen sensor
FixL
nitrogen fixation gene expression regulator
GcHK
globin-coupled histidine kinase
GCS
globin-coupled sensor
GReg
globin-coupled regulator
HemAT
haem-based aerotaxis transducer
HemDGC
haem-containing diguanylate cyclase
HNOB
haem NO-binding domain
mPER2
mammalian Period protein 2
MtR
non-haem-coupled regulator from
Moorella thermoacetica
NPAS2
neuronal PAS domain protein 2
PAS
Per-Arnt-Sim domain
PDE
phosphodiesterase
PDEA1
haem-containing phosphodiesterase A1
pXO1-118 and pXO2-61
non-haem-coupled sporulation inhibitory proteins from
Bacillus
anthracis
RcoM
CO-responsive transcription regulator
RNAP
RNA polymerase
RsbR
nonhaem-coupled
s
B regulator
SwMb Sperm whale
myoglobin
tGCS
truncated globin-coupled sensor
1. INTRODUCTION AND BACKGROUND: WHY
HAEM-BASED SENSORS?
The haem-based sensors represent a class of chimeric multi-domain
proteins in which a haem-binding sensor domain perceives changes in
the intracellular or extracellular environment and converts them into a signal
that activates or inactivates the fused transmitter domain.
There is evidence to demonstrate how modularity of proteins is funda-
mental for efficient transduction pathways involved in gene transcription
(
McAdams & Shapiro, 2003
), biochemical reactions (
Papin, Reed, &
Palsson, 2004
), and protein-protein interactions (
Reichmann et al.,
2005
). In this view, the haem-based sensors represent an example of highly
specialized modular proteins evolved in nature to provide adequate answers
to changing conditions, for example, oscillation of the nature and concen-
tration of environmental gases.
The haem-binding domain is a highly efficient and sensitive sensor.
Indeed, the haem-iron atom is chemically very reactive. It can change its
