ID | 7 |
Eprint ID | 7
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FullText URL | |
Title Alternative | ATP-citrate Lyase: The key enzyme of the reductive TCA cycle
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Author | |
Abstract | Almost all organic compounds which construct life are derived from carbon dioxide (CO2) assimilated by autotrrophic organisms.The reductive tricarboxylic acid (RTCA) cycle functions as a carbon dioxide fixation pathway, distinct from Calvin cycle, in a green sulfur bacterium Chlorobium limicola. ATP-citrate lyase (ACL) is one of the key enzymes of this cycle. The enzyme of C. limicola (Cl-ACL) was encoded in two adjacent open reading frames, aclB(1197bp) and aclA(1827bp), whose products showed signficant similarity to the N- and C-terminal regions of the human enzyme, respectively. Heterologous expression of these genes in Escherichia coli proved that both gene products were essential for ACL activity. Kinetic examination of the enzyme revealed that the enzyme displayed typical Michaelis-Monten kinetics toward ATP with an apparent Km value of 0.19mM. However, strong negative cooperativity was observed with respect to citrate binding. ADP was a competitive inhibitor of ATP with a Kj value of 0.036mM. Together with the feature that the enzyme catalyzed the reaction only in the direction of citrate cleavage, these kinetic properties indicated that Cl-ACL can regulate both the direction and carbon flux of the RTCA cycle in C. limicola.
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Keywords | CO2 fixation
Reductive TCA cycle
ATP-citrate lyase
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Published Date | 2005-02-01
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Publication Title |
岡山大学農学部学術報告
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Publication Title Alternative | Scientific reports of the Faculty of Agriculture, Okayama University
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Volume | volume94
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Issue | issue1
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Publisher | 岡山大学農学部
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Publisher Alternative | Faculty of Agriculture,Okayama University
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Start Page | 39
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End Page | 45
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ISSN | 0474-0254
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NCID | AN00033029
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Content Type |
Departmental Bulletin Paper
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language |
Japanese
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File Version | publisher
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Refereed |
False
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Eprints Journal Name | srfa
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