Biology Reference
In-Depth Information
Su
et al
. (2007) conducted a computational prediction analysis of Pho regulons in 19 sequenced
cyanobacterial genomes and found orthologues of SphR (sll0337) of
Synechocystis
sp. strain PCC
6803 in 16 genomes (
A
.
variabilis
ATCC 29413,
Anabaena
sp. strain PCC 7120 ,
G
.
violaceus
PCC 7421,
P
.
marinus
MED4, MIT9312, MIT9313, NATL2A,
S
.
elongatus
PCC 7942,
S
.
elongatus
PCC 6301,
Synechococcus
sp. strain WH8102, CC9605,
Synechococcus
sp. strain JA-3-3-A'b,
Synechococcus
sp. strain
JA-2-3B'a (2-13)
Synechocystis
sp. strain PCC 6803,
T. elonagtus
BF-1 and
T
.
erythraeum
IMS101) and
absent in three of them (
P
.
marinus
CCMP1375,
Synechococcus
sp. strain CC9902 and CC9311). The
sphS
and
sphR
genes are predicted to be present in the same operon (in
A
.
variabilis
ATCC 29413,
Anabaena
sp. strain PCC 7120,
P
.
marinus
MED4, MIT9312, NATL2A and WH8102,
Synechococcus
sp. CC9605,
Synechococcus
sp. strain JA-3-3-A'b,
Synechococcus
sp. strain JA-2-3B'a (2-13),
S
.
elongatus
PCC 7942,
S
.
elongatus
PCC 6301) or split into two separate operons (as in
G
.
violaceus
PCC 7421,
T
.
elongatus
BF-1 and
Synechocystis
sp. strain PCC 6803). In the rest of the two cyanobacterial genomes the
sphS
gene is either not encoded (
T
.
erythraeum
IMS101) or has undergone frame-shift mutation (
P
.
marinus
MIT 9313). The activation of the genes of P
i
-intake by SphR is due to its binding to at least three
tandem repeats of 8 bp, i.e. CTTAACCT collectively designated as Pho-boxes (Suzuki
et al
., 2004).
With the help of the computational program so developed, Su
et al
. (2007) found Pho-boxes for genes
transcribing for ABC-type P
i
Pst transporter complex genes in most of these genomes. The components
of P
i
-transporter identifi ed were a phosphate-binding subunit PstS, the transmembrane subunits PstC
and PstA and the ATP-binding subunit PstB and the respective genes form an operon,
pstS
-
C
-
A
-
B
.
However, in some of them
pstS
gene is present separately (as in
P
.
marinus
strains CCMP1375, MED4,
MIT9312, MIT9313 and
Synechococcus
sp. CC9605). An additional phosphate-binding subunit SphX,
encoded by
sphX
, is present in the Pst transporter complex in case of
A
.
variabilis
ATCC 29413,
Anabaena
sp. strain PCC 7120,
G.
violaceus
PCC 7421,
Synechococcus
sp. strain WH8102,
S
.
elongatus
PCC 6301,
S
.
elongatus
PCC 7942,
Synechocystis
sp. strain PCC 6803,
T
.
elongatus
BF-1 and
T
.
erythraeum
IMS101.
Phosphonate utilizing genes (of
Anabaena
sp. strain PCC 7120,
Synechococcus
sp. strain JA-2-3B'a (2-13)
and T.
erythraeum
IMS101) and phosphatase A (
phoA
) genes (of
A
.
variabilis
ATCC 29413,
Anabaena
sp.
strain PCC 7120,
G
.
violaceus
PCC 7421,
P
.
marinus
MED4, MIT9312, NATL2A,
S
.
elongatus
PCC 6301,
S
.
elongatus
PCC 7942,
Synechococcus
sp. strain WH8102,
Synechococcus
sp. strain JA-3-3-A'b,
Synechococcus
sp. strain JA-2-3B'a (2-13) and
Synechocystis
sp. strain PCC 6803) and extracellular nuclease (
nucH
)
genes that can utilize the P
i
moiety from nucleic acids in the environment (in case of
A
.
variabilis
ATCC
29413,
Anabaena
sp. strain PCC 7120,
S
.
elongatus
PCC 6301 and
S
.
elongatus
PCC 7942) all possess high
scoring SphR-binding sites suggesting that they are under the regulation of SphR.
b) Transcription factors
: Wu
et al
. (2007) created a database (cTF) containing 1288 putative transcription
factors from 21 fully sequenced cyanobacterial genomes. This database enables one to identify
the genes encoding transcription factors from any selected genome and is freely accessible
at http://cegw.com/.
N
.
punctiforme
PCC 73102 genome contains 13 apparent alternative σ
70
subunits in addition to the primary σ
70
subunit. Campbell
et al
. (1998) indicated that it is due to
mutation of only one alternative σ
70
the phenotype of
N
.
punctiforme
PCC 73102 changed to a
higher symbiotic interaction. The substantial capacity of
N
.
punctiforme
PCC 73102 for differential
gene expression in response to a variety of environmental conditions is revealed by the presence
of 57 ancillary transcriptional regulatory proteins. At least 67% of these bear resemblance to
regulatory proteins such as TetR, XylR and ArsA. Besides, there are genes that encode proteins
AraC (6 copies), LysR (8 copies) and MocR (two copies; Meeks
et al
., 2001). Nakamura
et al
. (2002)
allocated 21 genes for transcription factors in
T
.
elongatus
BP-1which are categorized into LuxR
family (4 genes), OmpR family (7 genes), LysR family (3 genes,
rbcR,
ntcB
and
ndhR
), CRP family
