4quw
Crystal structure of the apo form of cyanobacterial aldehyde-deformylating oxygenase
Structural highlights
FunctionALDEC_SYNE7 Catalyzes the decarbonylation of fatty aldehydes to alkanes. Requires the presence of ferredoxin, ferredoxin reductase and NADPH for in vitro decarbonylase activity (By similarity). Involved in the biosynthesis of alkanes, mainly heptadecane and pentadecane.[HAMAP-Rule:MF_00931][1] Publication Abstract from PubMedThe fatty alk(a/e)ne biosynthesis pathway found in cyanobacteria gained tremendous attention in recent years as a promising alternative approach for biofuel production. Cyanobacterial aldehyde-deformylating oxygenase (cADO), which catalyzes the conversion of Cn fatty aldehyde to its corresponding Cn-1 alk(a/e)ne, is a key enzyme in that pathway. Due to its low activity, alk(a/e)ne production by cADO is an inefficient process. Previous biochemical and structural investigations of cADO have provided some information on its catalytic reaction. However, the details of its catalytic processes remain unclear. Here we report five crystal structures of cADO from the Synechococcus elongates strain PCC7942 in both its iron-free and iron-bound forms, representing different states during its catalytic process. Structural comparisons and functional enzyme assays indicate that Glu144, one of the iron-coordinating residues, plays a vital role in the catalytic reaction of cADO. Moreover, the helix where Glu144 resides exhibits two distinct conformations that correlates with the different binding states of the di-iron center in cADO structures. Therefore, our results provide a structural explanation for the highly labile feature of cADO di-iron center, which we proposed to be related to its low enzymatic activity. On the basis of our structural and biochemical data, a possible catalytic process of cADO was proposed, which could aid the design of cADO with improved activity. Structural insights into the catalytic mechanism of aldehyde-deformylating oxygenases.,Jia C, Li M, Li J, Zhang J, Zhang H, Cao P, Pan X, Lu X, Chang W Protein Cell. 2014 Dec 9. PMID:25482408[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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