The crystal structure of the tetrameric DABA-aminotransferase EctB, a rate-limiting enzyme in the ectoine biosynthesis pathway.

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