Biology Reference
In-Depth Information
Figure 7.4
Physical map of the putative genes involved in the polymerization, chain
length control, and export of the EPS in the three morphological distinct types of cya-
nobacteria. The deduced protein sequences encoded by these genes were submitted
to an
in silico
analysis in order to identify the conserved motifs of interest. This analysis
was performed using the following bioinformatic tools: Blastp, cDART (at NCBI -
http://
www.ncbi.nlm.nih.gov/
), and SMART (at EMBL -
http://smart.embl-heidelberg.de/
)
. In
general, several copies of a specific gene could be identified in a single cyanobacte-
rial strain. In a given organism, the copy that has the highest probability to be related
to the EPS production is designated by
1
(taking into account both the percentage of
identity with the corresponding sequences in other organisms, and the position of the
gene in relation to others involved in the same process), the other copies are numbered
subsequently. In
Lyngbya
sp. and
Nostoc punctiforme
the genome region containing all
wz_
, except
wzb
, is underlined with a dashed line. ? indicates that the gene
wzy2
from
Lyngbya
is the one having the lowest homology to the available
wzy
sequences. Gen-
Bank accession numbers: AAXW00000000 (
Cyanothece
sp. CCY 0110), AAVU00000000
(
Lyngbya
sp. PCC 8106), and CP001037 (
Nostoc punctiforme
ATCC 29133).
(Retrieved from
Pereira et al. (2009)
).
Whitfield & Larue, 2008
). Using this information, a working model for the
assembly and export of cyanobacterial EPS following the general steps of the
Wzy-dependent pathway was proposed (
Pereira et al., 2009
).
Despite these first insights on the mechanisms underlying EPS pro-
duction in cyanobacteria, it is still necessary to understand, from a biologi-
cal perspective, the existence of the multiple copies of EPS-related genes,
as well as their organization and regulation within the cyanobacterial
