Biology Reference
In-Depth Information
ntcA
Gene expressed from three consecutive promoters: a proximal promoter (TSP -49) preceded by
a putative −10 determinant and an NtcA-binding site centred at position −54.5 with regard
to the TSP, which is activated at intermediate stages of heterocyst differentiation, is the major
promoter used in mature heterocysts and, when isolated from other promoters, shows activity
in all the cells of the filament, although expression increases in proheterocysts dependent on
NtcA and HetR; a vegetative-type promoter (TSP -136) preceded by a putative −10 element
and a poor −35 element, with an NtcA-binding site (centred at −143.5) that overlaps the
−10 box and could have a repressor role on this promoter; and a distal promoter (TSP -180)
activated transiently at intermediate stages of heterocyst differentiation, dependent on NtcA
and HetR, upstream of which only an imperfect −10 box can be recognized.
Muro-Pastor
et al., 2002
;
Olmedo-Verd
et al., 2006
,
2008
;
Rama-
subramanian,
Wei, Oldham, &
Golden, 1996
patA
Gene expressed from a proximal promoter (TSP -305) that is activated upon N stepdown in
all cells of the filament in a HetR-dependent manner and is negatively autoregulated, and
from distal promoters (TSP -614 and TSP -645) whose combined expression increases early
principally in the differentiating cells. Two putative NtcA-binding sites (centred at positions
−110 and −249) have been implicated in
patA
activation. However, because of their location
downstream from the reported TSPs, a direct activator role of NtcA bound to these sites on
transcription from those TSPs is difficult to envision.
Bastet et al., 2010
;
Young-Robbins
et al., 2010
patS
Gene transcribed from a weak promoter in vegetative cells (TSP -314) and a strong inducible
one (TSP -39) in differentiating cells.
Yoon & Golden,
2001
petH
Gene expressed from a constitutive promoter (TSP -63) and an NtcA-dependent inducible
promoter (TSP -188) that is functional in mature heterocysts. Both of them present recogniz-
able −10 determinants.
Valladares, Muro-
Pastor, Fillat,
Herrero, &
Flores, 1999
pipX
Gene expressed from three promoters: a Class II NtcA-activated promoter (TSP -436), a vegeta-
tive promoter (TSP -107) with consensus −10 and −35 boxes, and an NtcA- and HetR-
dependent promoter (TSP -388) with a recognizable −10 box.
Valladares et al.,
2011
Gene expressed from at least two promoters, of which one (TSP -328) is constitutive and
another (TSP -868) is active with and without combined nitrogen, but its activity increases
under N deprivation. Both promoters are preceded by good −10 and −35 hexamers.
Brahamsha &
Haselkorn, 1991
sigA
