Abstract
The X-ray crystal structure of the substrate-free form of phycocyanobilin (PCB)-ferredoxin oxidoreductase (PcyA; EC 1.3.7.5) from the cyanobacterium Nostoc sp. PCC7120 has been solved at 2.5 A resolution. A comparative analysis of this structure with those recently reported for substrate-bound and substrate-free forms of PcyA from the cyanobacterium Synechocystis sp. PCC6803 (Hagiwara et al. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 27-32; Hagiwara et al. (2006) FEBS Lett. 580, 3823-3828) provides a compelling picture of substrate-induced changes in the PcyA enzyme and the chemical basis of PcyA's catalytic activity. On the basis of these structures and the biochemical analysis of site-directed mutants of Nostoc PcyA, including mutants reported in recent studies (Tu et al. (2006) J. Biol. Chem. 281, 3127-3136) as well as mutants described in this study, a revised mechanism for the PcyA-mediated four-electron reduction of biliverdin IXα to 3E/3Z-phycocyanobilin via enzyme-bound bilin radical intermediates is proposed. The mechanistic insight of these studies, along with homology modeling, have provided new insight into the catalytic mechanisms of other members of the ferredoxin-dependent bilin reductase family that are widespread in oxygenic photosynthetic organisms.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1484-1494 |
| Number of pages | 11 |
| Journal | Biochemistry |
| Volume | 46 |
| Issue number | 6 |
| DOIs | |
| State | Published - Feb 13 2007 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Insight into the radical mechanism of phycocyanobilin-ferredoxin oxidoreductase (PcyA) revealed by X-ray crystallography and biochemical measurements. / Tu, Shih Long; Rockwell, Nathan C.; Lagarias, J. Clark; Fisher, Andrew J.
In: Biochemistry, Vol. 46, No. 6, 13.02.2007, p. 1484-1494.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Insight into the radical mechanism of phycocyanobilin-ferredoxin oxidoreductase (PcyA) revealed by X-ray crystallography and biochemical measurements
AU - Tu, Shih Long
AU - Rockwell, Nathan C.
AU - Lagarias, J. Clark
AU - Fisher, Andrew J
PY - 2007/2/13
Y1 - 2007/2/13
N2 - The X-ray crystal structure of the substrate-free form of phycocyanobilin (PCB)-ferredoxin oxidoreductase (PcyA; EC 1.3.7.5) from the cyanobacterium Nostoc sp. PCC7120 has been solved at 2.5 A resolution. A comparative analysis of this structure with those recently reported for substrate-bound and substrate-free forms of PcyA from the cyanobacterium Synechocystis sp. PCC6803 (Hagiwara et al. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 27-32; Hagiwara et al. (2006) FEBS Lett. 580, 3823-3828) provides a compelling picture of substrate-induced changes in the PcyA enzyme and the chemical basis of PcyA's catalytic activity. On the basis of these structures and the biochemical analysis of site-directed mutants of Nostoc PcyA, including mutants reported in recent studies (Tu et al. (2006) J. Biol. Chem. 281, 3127-3136) as well as mutants described in this study, a revised mechanism for the PcyA-mediated four-electron reduction of biliverdin IXα to 3E/3Z-phycocyanobilin via enzyme-bound bilin radical intermediates is proposed. The mechanistic insight of these studies, along with homology modeling, have provided new insight into the catalytic mechanisms of other members of the ferredoxin-dependent bilin reductase family that are widespread in oxygenic photosynthetic organisms.
AB - The X-ray crystal structure of the substrate-free form of phycocyanobilin (PCB)-ferredoxin oxidoreductase (PcyA; EC 1.3.7.5) from the cyanobacterium Nostoc sp. PCC7120 has been solved at 2.5 A resolution. A comparative analysis of this structure with those recently reported for substrate-bound and substrate-free forms of PcyA from the cyanobacterium Synechocystis sp. PCC6803 (Hagiwara et al. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 27-32; Hagiwara et al. (2006) FEBS Lett. 580, 3823-3828) provides a compelling picture of substrate-induced changes in the PcyA enzyme and the chemical basis of PcyA's catalytic activity. On the basis of these structures and the biochemical analysis of site-directed mutants of Nostoc PcyA, including mutants reported in recent studies (Tu et al. (2006) J. Biol. Chem. 281, 3127-3136) as well as mutants described in this study, a revised mechanism for the PcyA-mediated four-electron reduction of biliverdin IXα to 3E/3Z-phycocyanobilin via enzyme-bound bilin radical intermediates is proposed. The mechanistic insight of these studies, along with homology modeling, have provided new insight into the catalytic mechanisms of other members of the ferredoxin-dependent bilin reductase family that are widespread in oxygenic photosynthetic organisms.
UR - http://www.scopus.com/inward/record.url?scp=33846985274&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33846985274&partnerID=8YFLogxK
U2 - 10.1021/bi062038f
DO - 10.1021/bi062038f
M3 - Article
C2 - 17279614
AN - SCOPUS:33846985274
VL - 46
SP - 1484
EP - 1494
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 6
ER -