TY - JOUR
T1 - The Crystal Structure of a Bacterial l -Arabinonate Dehydratase Contains a [2Fe-2S] Cluster
AU - Rahman, Mohammad
AU - Andberg, Martina
AU - Thangaraj, Senthil
AU - Parkkinen, Tarja
AU - Penttilä, Merja
AU - Jänis, Janne
AU - Koivula, Anu
AU - Rouvinen, Juha
AU - Hakulinen, Nina
PY - 2017/7/21
Y1 - 2017/7/21
N2 - We present a novel crystal structure of the IlvD/EDD family enzyme, l-arabinonate dehydratase from Rhizobium leguminosarum bv. trifolii (RlArDHT, EC 4.2.1.25), which catalyzes the conversion of l-arabinonate to 2-dehydro-3-deoxy-L-arabinonate. The enzyme is a tetramer consisting of a dimer of dimers, where each monomer is composed of two domains. The active site contains a catalytically important [2Fe-2S] cluster and Mg2+ ion and is buried between two domains, and also at the dimer interface. The active site Lys129 was found to be carbamylated. Ser480 and Thr482 were shown to be essential residues for catalysis, and the S480A mutant structure showed an unexpected open conformation in which the active site was more accessible for the substrate. This structure showed the partial binding of L-arabinonate, which allowed us to suggest that the alkoxide ion form of the Ser480 side chain functions as a base and the [2Fe-2S] cluster functions as a Lewis acid in the elimination reaction.
AB - We present a novel crystal structure of the IlvD/EDD family enzyme, l-arabinonate dehydratase from Rhizobium leguminosarum bv. trifolii (RlArDHT, EC 4.2.1.25), which catalyzes the conversion of l-arabinonate to 2-dehydro-3-deoxy-L-arabinonate. The enzyme is a tetramer consisting of a dimer of dimers, where each monomer is composed of two domains. The active site contains a catalytically important [2Fe-2S] cluster and Mg2+ ion and is buried between two domains, and also at the dimer interface. The active site Lys129 was found to be carbamylated. Ser480 and Thr482 were shown to be essential residues for catalysis, and the S480A mutant structure showed an unexpected open conformation in which the active site was more accessible for the substrate. This structure showed the partial binding of L-arabinonate, which allowed us to suggest that the alkoxide ion form of the Ser480 side chain functions as a base and the [2Fe-2S] cluster functions as a Lewis acid in the elimination reaction.
UR - http://www.scopus.com/inward/record.url?scp=85025159562&partnerID=8YFLogxK
U2 - 10.1021/acschembio.7b00304
DO - 10.1021/acschembio.7b00304
M3 - Article
VL - 12
SP - 1919
EP - 1927
JO - ACS Chemical Biology
JF - ACS Chemical Biology
SN - 1554-8929
IS - 7
ER -