2F99

Crystal structure of the polyketide cyclase AknH with bound substrate and product analogue: implications for catalytic mechanism and product stereoselectivity.

2F99 の概要

• エントリーDOI: 10.2210/pdb2f99/pdb
• 関連するPDBエントリー: 2F98
• 分子名称: Aklanonic Acid methyl Ester Cyclase, AknH, SULFATE ION, {3-[(1R,3S)-1,3-DIHYDROXYPENTYL]-4,5,9,10-TETRAHYDROXY-2-ANTHRYL}ACETATE, ... (4 entities in total)
• 機能のキーワード: anthracycline, polyketide cyclase, stereoselectivity, aklavinone, biosynthetic protein
• 由来する生物種: Streptomyces galilaeus
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 74518.90

構造登録者

Kallio, P.,Sultana, A.,Neimi, J.,Mantsala, P.,Schneider, G. (登録日: 2005-12-05, 公開日: 2006-02-14, 最終更新日: 2023-08-30)

主引用文献

Kallio, P.,Sultana, A.,Niemi, J.,Schneider, G.
Crystal structure of the polyketide cyclase AknH with bound substrate and product analogue: implications for catalytic mechanism and product stereoselectivity.
J.Mol.Biol., 357:210-220, 2006

PubMed Abstract: AknH is a small polyketide cyclase that catalyses the closure of the fourth carbon ring in aclacinomycin biosynthesis in Streptomyces galilaeus, converting aklanonic acid methyl ester to aklaviketone. The crystal structure analysis of this enzyme, in complex with substrate and product analogue, showed that it is closely related in fold and mechanism to the polyketide cyclase SnoaL that catalyses the corresponding reaction in the biosynthesis of nogalamycin. Similarity is also apparent at a functional level as AknH can convert nogalonic acid methyl ester, the natural substrate of SnoaL, to auraviketone in vitro and in constructs in vivo. Despite the conserved structural and mechanistic features between these enzymes, the reaction products of AknH and SnoaL are stereochemically distinct. Supplied with the same substrate, AknH yields a C9-R product, like most members of this family of polyketide cyclases, whereas the product of SnoaL has the opposite C9-S stereochemistry. A comparison of high-resolution crystal structures of the two enzymes combined with in vitro mutagenesis studies revealed two critical amino acid substitutions in the active sites, which contribute to product stereoselectivity in AknH. Replacement of residues Tyr15 and Asn51 of AknH, located in the vicinity of the main catalytic residue Asp121, by their SnoaL counter-parts phenylalanine and leucine, respectively, results in a complete loss of product stereoselectivity.

PubMed: 16414075
DOI: 10.1016/j.jmb.2005.12.064

実験手法

X-RAY DIFFRACTION (1.9 Å)