title: Structure of putrescine aminotransferase from Escherichia coli provides insights into the substrate specificity among class III aminotransferases.
abstract: YgjG is a putrescine aminotransferase enzyme that transfers amino groups from compounds with terminal primary amines to compounds with an aldehyde group using pyridoxal-5'-phosphate (PLP) as a cofactor. Previous biochemical data show that the enzyme prefers primary diamines, such as putrescine, over ornithine as a substrate. To better understand the enzyme's substrate specificity, crystal structures of YgjG from Escherichia coli were determined at 2.3 and 2.1 Å resolutions for the free and putrescine-bound enzymes, respectively. Sequence and structural analyses revealed that YgjG forms a dimer that adopts a class III PLP-dependent aminotransferase fold. A structural comparison between YgjG and other class III aminotransferases revealed that their structures are similar. However, YgjG has an additional N-terminal helical structure that partially contributes to a dimeric interaction with the other subunit via a helix-helix interaction. Interestingly, the YgjG substrate-binding site entrance size and charge distribution are smaller and more hydrophobic than other class III aminotransferases, which suggest that YgjG has a unique substrate binding site that could accommodate primary aliphatic diamine substrates, including putrescine. The YgjG crystal structures provide structural clues to putrescine aminotransferase substrate specificity and binding.
authors.affiliation: Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Korea.
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Cha
authors.affiliation: Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Korea.
authors.forename: Jae-Hee
authors.initials: JH
authors.lastname: Jeong
authors.affiliation: Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Korea.
authors.forename: Catleya
authors.initials: C
authors.lastname: Rojviriya
authors.affiliation: Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Korea.
authors.forename: Yeon-Gil
authors.initials: YG
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011489:Protein Denaturation; D011700:Putrescine / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D000637:Transaminases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D011732:Pyridoxal Phosphate; D000637:Transaminases; D011700:Putrescine