Biology Reference
In-Depth Information
Figure 11:
(A) Physical map of the extended hyp-operon, covering a region of almost 14 kb, in
Anabaena
sp. strain PCC 7120. Apart
from the
hyp
-genes (depicted in black) the region also includes fi ve genes upstream of
hypF
(depicted in grey), the two genes
downstream of
hypB
(depicted in grey), and
asr0697
(between
hypD
and
hypE
, depicted in grey). The overlapping cDNA of the
region are marked a-i. Identifi ed transcriptional start points, TSP, of the extended
hyp
-operon located upstream of
asr0689
,
hypF
and
hypC
are marked with arrows. Number R1-R6 represents the intergenic regions where conserved sequences were found in
the extended
hyp
-operon. (B) Agarose gel showing the overlapping amplifi ed PCR products, 1-22, of the RT-PCR experiments, a-i.
(C) Primer pairs (1-22) used in the mapping of the extended
hyp
-operon consisting of overlapping cDNA (a-i). The size indicates
the expected length of the PCR-product of the forward primer together with the reverse tag-primer. With the kind permission
of P. Lindblad, Department of Photochemistry and Molecular Science, Uppsala University, P.O. Box 523, S 75120, Uppsala,
Sweden [Agervald
et al.
(2008)
BMC Microbiology
8
:69; doi:10.1186/1471-2180-8-69].
The arrangement of genes for the small and large subunit of uptake hydrogenases in most
of the cyanobacteria examined is almost contiguous with the
hupS
being present upstream of the
hupL
gene. The 10.5 kb element present in
hupL
gene is excised during heterocyst differentiation
in
Anabaena
sp. strain PCC 7120 which has already been described under section dealing with
Genome Rearrangement. The intergenic region of
hupSL
in heterocystous cyanobacteria is variable
(such as 75 bp in
A
.
variabilis
ATCC 29413, 68 bp in
Anabaena
sp. strain PCC 7120, and
N
.
muscorum
CCAP 1453/12, 144 bp in
Nostoc
sp. strain PCC 7422 and 192 bp
N
.
punctiforme
ATCC 29133) with
prominent feature being the presence of short tandemly repeated repetitive sequences (Tamagnini
et al
., 2002, 2007). Carrasco
et al
. (1995) fi rst demonstrated that the
hupSL
transcripts appear during
