Biology Reference
In-Depth Information
Figure 5.3
The disulfide reduction pathways.
Fed: Ferredoxin, FTR: Ferredoxin
dependant thioredoxin reductase, GR: Glutathione reductase, Grx: Glutaredoxin, GSH:
Glutathione (reduced form), GSSG: Glutathione disulfide (oxidized glutathione), NTR:
NADPH-dependant thioredoxin reductase, -S-SG: Protein-glutathione mixed disulfide,
Trx: Thioredoxin.
The four Trxs of
Synechocystis
PCC 6803 belong to four different Trx types
encoded by the genes trxA (m-type; slr0623), trxB (x-type; slr1139), trxC
(sll1057) and trxQ (y-type; slr0233). Both trxA and trxC are essential for
normal photoautotrophic growth (their attempted inactivation invariably
led to a heteroploid strain harbouring both wild-type and mutant copies
of the chromosome, with and without the studied trx genes (
Florencio,
Perez-Perez, Lopez-Maury, Mata-Cabana, & Lindahl, 2006
). By contrast,
fully segregated
trxB
-less and
trxQ
-less mutants were obtained indicating
that both TrxB and TrxQ are dispensable to cell growth. Furthermore, a
strain containing a mutated version of TrxB (TrxB
C34S
) was used to iden-
tify the potential in vivo TrxB targets by a proteomic analysis (
Perez-Perez,
Martin-Figueroa, & Florencio, 2009
). These TrxB targets are involved in
protein synthesis (ribosomal proteins), metabolism of amino acids (gluta-
mine synthase, cysteine synthase) and sugars (fructose bisphosphate aldolase,
