Information Technology Reference
In-Depth Information
Table 6.1 Structures of pheromones and inhibitors.
Pheromon/inhibitor
Peptide structure
cPD1
H-Phe-Leu-Val-Met-Phe-Leu-Ser-Gly-OH
iPD1
H-Ala-Leu-Ile-Leu-Thr-Leu-Val-Ser-OH
cAD1
H-Leu-Phe-Ser-Leu-Val-Leu-Ala-Gly-OH
iAD1
H-Leu-Phe-Val-Val-Thr-Leu-Val-Gly-OH
cCF10
H-Leu-Val-Thr-Leu-Val-Phe-Val-OH
iCF10
H-Ala-Ile-Thr-Leu-Ile-Phe-Ile-OH
cAM373
H-Ala-Ile-Phe-Ile-Leu-Ala-Ser-OH
iAM373
H-Ser-Ile-Phe-Thr-Leu-Val-Ala-OH
cOB1
H-Val-Ala-Val-Leu-Val-Leu-Gly-Ala-OH
iOB1
H-Ser-Leu-Thr-Leu-Ile-Leu-Ser-Ala-OH
Conjugative Plasmids, Pheromones, and Inhibitors
Many conjugative plasmids are found in various
E. faecalis
strains (Table 6.2).
These plasmids are classified by phenotype in terms of the type of pheromone
to which they can respond. A plasmid is responsive only to its corresponding
class of pheromone.
In the free-living state,
E. faecalis
constantly produce pheromones of every
class, unless they carry a conjugative plasmid. When they do carry a conjugative
plasmid, corresponding pheromone production is reduced by the specific regu-
latory mechanism directed by the genes on the conjugative plasmid (
pheromone
shutdown
).
In addition,
E. faecalis
that carry a conjugative plasmid produce a pheromone
inhibitor. The inhibitor gene is located on the plasmid. Pheromone inhibitors
are all seven- or eight-residue amino peptides. The amino acid sequences of in-
hibitors are partially homologous to that of pheromones of the same class (Table
6.1). Pheromone inhibitors competitively bind the pheromone receptor and in-
hibit the downstream pathway of cell activation induced by the pheromone.
IMPLEMENTATION OF THE INFORMATION GATE
The conjugation system of
E. faecalis
is applicable to building information
processors for cellular computing. Pheromones serve as signals, and the infor-
mation written in plasmids is transferred from one cell to another.
E. faecalis
Information Gate
Using combined inhibitors, we designed a logically controlled DNA transporter
(Figure 6.2). Pheromone
C
i
and inhibitor
I
i
are used as gate signals. Depending
