4I45

Crystal Structure of Orf6 protein from Photobacterium profundum, Mg2+-bound form

4I45 の概要

• エントリーDOI: 10.2210/pdb4i45/pdb
• 関連するPDBエントリー: 3R87
• 分子名称: ORF6 thioesterase, MAGNESIUM ION (3 entities in total)
• 機能のキーワード: thioesterase, polyketide synthase, polyunsaturated fatty acid, hot dog, hydrolase
• 由来する生物種: Photobacterium profundum
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 15587.00

構造登録者

Rodriguez-Guilbe, M.M.,Baerga-Ortiz, A.,Schreiter, E.R. (登録日: 2012-11-27, 公開日: 2013-02-27, 最終更新日: 2023-09-20)

主引用文献

Rodriguez-Guilbe, M.,Oyola-Robles, D.,Schreiter, E.R.,Baerga-Ortiz, A.
Structure, Activity, and Substrate Selectivity of the Orf6 Thioesterase from Photobacterium profundum.
J.Biol.Chem., 288:10841-10848, 2013

PubMed Abstract: Thioesterase activity is typically required for the release of products from polyketide synthase enzymes, but no such enzyme has been characterized in deep-sea bacteria associated with the production of polyunsaturated fatty acids. In this work, we have expressed and purified the Orf6 thioesterase from Photobacterium profundum. Enzyme assays revealed that Orf6 has a higher specific activity toward long-chain fatty acyl-CoA substrates (palmitoyl-CoA and eicosapentaenoyl-CoA) than toward short-chain or aromatic acyl-CoA substrates. We determined a high resolution (1.05 Å) structure of Orf6 that reveals a hotdog hydrolase fold arranged as a dimer of dimers. The putative active site of this structure is occupied by additional electron density not accounted for by the protein sequence, consistent with the presence of an elongated compound. A second crystal structure (1.40 Å) was obtained from a crystal that was grown in the presence of Mg(2+), which reveals the presence of a binding site for divalent cations at a crystal contact. The Mg(2+)-bound structure shows localized conformational changes (root mean square deviation of 1.63 Å), and its active site is unoccupied, suggesting a mechanism to open the active site for substrate entry or product release. These findings reveal a new thioesterase enzyme with a preference for long-chain CoA substrates in a deep-sea bacterium whose potential range of applications includes bioremediation and the production of biofuels.

PubMed: 23430744
DOI: 10.1074/jbc.M112.446765

実験手法

X-RAY DIFFRACTION (1.4 Å)