Biology Reference
In-Depth Information
data that a small number of transcripts and a few proteins originated from
Synechocystis
genes in CB. These observations, together with the absence of a guest RNA polymerase,
imply that ribosomes play central roles for robust cellular gene networks. Results from
exchange of ribosomal RNA
23
suggest that chimera ribosomes are allowed only between
closely related species. The only way for CB to survive seems to avoid conflict interference
with and be in accordance with the host
B. subtilis
gene regulatory networks that are
essential for growth in
B. subtilis
medium. Transcriptome and proteome analyses for all the
intermediate strains should give remarkable clues, but remain to be done. These scenarios
might be examined by adopting guest genomes already synthesized, for example those
reported in
4
6
in the BGM host.
3
Lastly on the ribosomal RNA issues, there is a priori consensus for current molecular
phylogenic analyses consistent with the apparent lack of multiple
rrn
species carriers.
Exclusivity of distantly related ribosomal RNA species observed in CB gave the first
experimental basis on and coordinated with the present molecular phylogenic trees for
eubacteria.
STRUCTURAL CONSTRAINTS ON THE HOST GENOME
Bacterial genomes have to be replicated to produce offspring. Many circular bacterial
genomes possess particular sequences, called
oriC
and
terC
, where a new round of DNA
replication starts and two replication machineries meet.
24
Consensus molecular mechanisms
are drawn by a number of studies that two DNA replication machineries initiated at
oriC
divergently traverse half of a circular genome. Consequently, the right and left length
around the
oriC
terC
axis have to be similar in length, typically as shown for
E. coli
and
B. subtilis
. Logically, guest genomes megacloned at a single locus of the
B. subtilis
genome
increase the one replication length, causing significant imbalance around the original
oriC
terC
axis, as illustrated in
Figure 12.3C
. The degree of imbalance had not been known
232
I or II
oriC
oriC
terC
BGM
oriC
kb
terC
oriC
2200 kbp
2000 kbp
1100
CyanoBacillus
900
700
500
III or IV
terC
terC
oriC
200
III'
oriC
terC
terC
FIGURE 12.3C
Flexible size distribution of B. subtilis genome around the oriCterC axis. Symmetry around the oriCterC axis is obstinate to ensure growth. Growth
reduction by large DNA insertion (i.e. megacloning: top center) is compensated by DNA insertion into the opposite half to restore symmetry. Right: BGM
clones corresponding to I, II, III, and IV in
Figure 12.3A
were analyzed. Apparent deletion indicated by an arrow is observed from III
'
s, 1138 kbp. It was
concluded that guest genome part
,
1000 kbp displays stable, disregarding the right or left side of BGM. See text.
