Affiliation:
1. Department of Life Science and Basic Science Institute for Cell Damage Control, Sogang University, Seoul 121-742, South Korea
Abstract
ABSTRACT
The photosynthetic growth of
Synechocystis
sp. strain PCC 6803 is hampered by exogenously added bacteriochlorophyllide
a
(Bchlide
a
) in a dose-dependent manner. The growth inhibition caused by Bchlide
a
, however, is relieved by an increased level of exogenously added chlorophyllide
a
(Chlide
a
). The results are explained by the competitive inhibition of chlorophyll synthase by Bchlide
a
, with inhibition constants (
K
I
s) of 0.3 mM and 1.14 mM in the presence of sufficient geranylgeranyl pyrophosphate (GGPP) and phytyl pyrophosphate (PPP), respectively. Surprisingly, the bacteriochlorophyll synthase of
Rhodobacter sphaeroides
is inhibited competitively by Chlide
a
, with
K
I
s of 0.54 mM and 0.77 mM in the presence of sufficient GGPP and PPP, respectively. Consistently, exogenously added Chlide
a
inhibits the metabolic conversion of exogenously added Bchlide
a
to bacteriochlorophyll
a
by an
R. sphaeroides bchFNB-bchZ
mutant that neither synthesizes nor metabolizes Chlide
a
. The metabolic inhibition by Chlide
a
, however, is relieved by the elevated level of Bchlide
a
. Thus, the chlorophyll synthase of
Synechocystis
sp. PCC 6803 and the bacteriochlorophyll synthase of
R. sphaeroides
, both of which perform ping-pong-type reactions, are inhibited by Bchlide
a
and Chlide
a
, respectively. Although neither inhibitor is catalyzed by the target enzyme, inhibitions in the competitive mode suggest a structural similarity between their active sites.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Reference33 articles.
1. Physical Mapping and Functional Assignment of the Geranylgeranyl-Bacteriochlorophyll Reductase Gene,
bchP
, of
Rhodobacter sphaeroides
2. Addlesee, H. A., L. C. Gibson, P. E. Jensen, and C. N. Hunter. 1996. Cloning, sequencing and functional assignment of the chlorophyll biosynthesis gene, chlP, of Synechocystis sp. PCC6803. FEBS Lett. 389 : 126-130.
3. Physical Mapping of
bchG
,
orf427
, and
orf177
in the Photosynthesis Gene Cluster of
Rhodobacter sphaeroides
: Functional Assignment of the Bacteriochlorophyll Synthetase Gene
4. Allen, M. M. 1968. Simple conditions for growth of unicellular blue-green algae on plates. J. Phycol. 4 : 1-4.
5. Beale, S. I. 1993. Biosynthesis of cyanobacterial tetrapyrrole pigments: hemes, chlorophylls and phycobilins, p. 519-558. In D. A. Bryant (ed.), The molecular biology of cyanobacteria. Kluwer Academic Publishers, Dordrecht, the Netherlands.
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