Structural and biochemical characterization of the bilin lyase CpcS from Thermosynechococcus elongatus.
Cyanobacterial phycobiliproteins have evolved to capture light energy over most of the visible spectrum due to their bilin chromophores, which are linear tetrapyrroles that have been covalently attached by enzymes called bilin lyases. We report here the crystal structure of a bilin lyase of the CpcS family from Thermosynechococcus elongatus (TeCpcS-III). TeCpcS-III is a 10-stranded β barrel with two alpha helices and belongs to the lipocalin structural family. TeCpcS-III catalyzes both cognate as well as noncognate bilin attachment to a variety of phycobiliprotein subunits. TeCpcS-III ligates phycocyanobilin, phycoerythrobilin, and phytochromobilin to the alpha and beta subunits of allophycocyanin and to the beta subunit of phycocyanin at the Cys82-equivalent position in all cases. The active form of TeCpcS-III is a dimer, which is consistent with the structure observed in the crystal. With the use of the UnaG protein and its association with bilirubin as a guide, a model for the association between the native substrate, phycocyanobilin, and TeCpcS was produced.
Department of Biological Sciences, University of New Orleans , New Orleans, LA 70148, United States.
Christina M
CM
Kronfel
Alexandre P
AP
Kuzin
Farhad
F
Forouhar
Avijit
A
Biswas
Min
M
Su
Scott
S
Lew
Jayaraman
J
Seetharaman
Rong
R
Xiao
John K
JK
Everett
Li-Chung
LC
Ma
Thomas B
TB
Acton
Gaetano T
GT
Montelione
John F
JF
Hunt
Corry E C
CE
Paul
Tierna M
TM
Dragomani
M Nazim
MN
Boutaghou
Richard B
RB
Cole
Christian
C
Riml
Richard M
RM
Alvey
Donald A
DA
Bryant
Wendy M
WM
Schluchter
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D000458:Cyanobacteria / Q000201:enzymology*; D008190:Lyases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D052979:Phycobiliproteins / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D013057:Spectrum Analysis
D001426:Bacterial Proteins; D052979:Phycobiliproteins; D008190:Lyases