6RL5

The first crystal structure of the DABA aminotransferase EctB in the ectoine biosynthesis pathway of the model organism Chromohalobacter salexigens DSM 3034

6RL5 の概要

• エントリーDOI: 10.2210/pdb6rl5/pdb
• 分子名称: Diaminobutyrate--2-oxoglutarate transaminase, PYRIDOXAL-5'-PHOSPHATE (3 entities in total)
• 機能のキーワード: ectoine, daba aminotransferase, osmoadaptation, transferase
• 由来する生物種: Chromohalobacter salexigens (strain DSM 3043 / ATCC BAA-138 / NCIMB 13768)
• タンパク質・核酸の鎖数: 8
• 化学式量合計: 378666.14

構造登録者

Hillier, H.T.,Altermark, B.,Leiros, I. (登録日: 2019-05-01, 公開日: 2020-03-11, 最終更新日: 2024-01-24)

主引用文献

Hillier, H.T.,Altermark, B.,Leiros, I.
The crystal structure of the tetrameric DABA-aminotransferase EctB, a rate-limiting enzyme in the ectoine biosynthesis pathway.
Febs J., 287:4641-4658, 2020

PubMed Abstract: l-2,4-diaminobutyric acid (DABA) aminotransferases can catalyze the formation of amines at the distal ω-position of substrates, and is the intial and rate-limiting enzyme in the biosynthesis pathway of the cytoprotecting molecule (S)-2-methyl-1,4,5,6-tetrahydro-4-pyrimidine carboxylic acid (ectoine). Although there is an industrial interest in the biosynthesis of ectoine, the DABA aminotransferases remain poorly characterized. Herein, we present the crystal structure of EctB (2.45 Å), a DABA aminotransferase from Chromohalobacter salexigens DSM 3043, a well-studied organism with respect to osmoadaptation by ectoine biosynthesis. We investigate the enzyme's oligomeric state to show that EctB from C. salexigens is a tetramer of two functional dimers, and suggest conserved recognition sites for dimerization that also includes the characteristic gating loop that helps shape the active site of the neighboring monomer. Although ω-transaminases are known to have two binding pockets to accommodate for their dual substrate specificity, we herein provide the first description of two binding pockets in the active site that may account for the catalytic character of DABA aminotransferases. Furthermore, our biochemical data reveal that the EctB enzyme from C. salexigens is a thermostable, halotolerant enzyme with a broad pH tolerance which may be linked to its tetrameric state. Put together, this study creates a solid foundation for a deeper structural understanding of DABA aminotransferases and opening up for future downstream studies of EctB's catalytic character and its redesign as a better catalyst for ectoine biosynthesis. In summary, we believe that the EctB enzyme from C. salexigens can serve as a benchmark enzyme for characterization of DABA aminotransferases. DATABASE: Structural data are available in PDB database under the accession number 6RL5.

PubMed: 32112674
DOI: 10.1111/febs.15265

実験手法

X-RAY DIFFRACTION (2.45 Å)