Biology Reference
In-Depth Information
these proteins accumulated a significant amount of changes leading to a con-
siderable phylogenetic distance. With few exceptions, the PCP homologues
from the same strain were present in different clusters, while the orthologues
from different organisms cluster together. These results suggest that they are
not the outcome of gene duplication events within each strain's genome, but
rather result of an earlier duplication/HGT event that occurred in a common
ancestral organism. For unicellular cyanobacteria, only three orthologues were
grouped in a cluster supported by a strong bootstrap value (cluster 1), together
with a short number of sequences from filamentous strains. Regarding other
cyanobacteria, a monophyletic cluster (cluster 2) comprising PCP orthologues
from filamentous strains was defined, whereas three different consistent clus-
ters comprising sequences from heterocystous strains could be observed (clus-
ters 9-11). Clusters 9 and 10 are supported by a bootstrap value of 99% each.
The synteny analysis of the genes encoding the PCP proteins from cluster 9
revealed that, with the exception of the
Nostoc
sp. PCC 7120 orthologue, these
genes are contiguous to those encoding a SpoIID domain-containing protein.
SpoIID are autolysins that hydrolyse the cell wall and drive membrane move-
ment during sporulation (
Meyer, Gutierrez, Pogliano, & Dworkin, 2010
). In
cyanobacteria, the role of these proteins is not clear although they do not seem
to be essential for cell division in the unicellular cyanobacterium
Synechocystis
50% are indicated in the tree branches. Three representatives from each of the groups
(A-F) defined in the study conducted by
Cuthbertson et al. (2009)
were selected as refer-
ence groups. Proteins from Gram-negative (Gram−) and Gram-positive bacteria are also
indicated (Gram+). Bootstrapped supporter clusters are indicated in each tree (Arabic
and Roman numbers). Grey background areas indicate putative PCP proteins identified
by BLAST homology searches that are phylogenetically distant from other cyanobacte-
rial homologues. Unicellular cyanobacteria:
Cyanothece
sp. CCY 0110 (
Cyanothece
CCY);
Cyanothece
sp. ATCC 51142 (
Cyanothece
ATCC);
Cyanothece
sp. PCC 7822 (
Cyanothece
PCC);
Microcystis aeruginosa
NIES-843 (
Microcystis aeruginosa
);
Prochlorococcus marinus
subsp.
marinus
str. CCMP 1375 (
P. marinus
CCMP);
Synechococcus elongatus
PCC 6301
(
S. elongatus
);
Thermosynechococcus elongatus
BP-1 (
T. elongatus
);
Synechocystis
sp. PCC
6803 (
Synechocystis
PCC);
Cyanobacterium
UCYN-A (
Cyanobacterium
UCYN_A);
Gloeo-
bacter violaceus
PCC 7421 (
G. violaceus
). Filamentous cyanobacteria:
Arthrospira platensis
NIES-39 (
A. platensis
);
Arthrospira maxima
CS-328 (
A. maxima
);
Lyngbya
sp. PCC 8106 (
Lyn-
gbya
PCC);
Oscillatoria
sp. PCC 6506 (
Oscillatoria
PCC);
Trichodesmium erythraeum
IMS101
(
Trichodesmium erythraeum)
;
Microcoleus chthonoplastes
PCC 7420 (
M. chthonoplastes
);
Microcoleus vaginatus
FGP-2 (
M. vaginatus
). Heterocystous cyanobacteria:
Nostoc azollae
0708 (
Nostoc azollae
);
Anabaena variabilis
ATCC 29413 (
Anabaena variabilis
);
Nodularia
spumigena
CCY 9414 (
N. spumigena
);
Nostoc punctiforme
PCC 73102 (
Nostoc punctiforme
);
Nostoc
sp. PCC 7120 (
Nostoc
PCC);
Cylindrospermopsis raciborskii
CS-505 (
C. raciborskii
).
