2b0j
From Proteopedia
The crystal structure of the apoenzyme of the iron-sulfur-cluster-free hydrogenase (Hmd)
Overview
The iron-sulphur cluster-free hydrogenase (Hmd, EC 1.12.98.2) from methanogenic archaea is a novel type of hydrogenase that tightly binds an iron-containing cofactor. The iron is coordinated by two CO molecules, one sulphur and a pyridone derivative, which is linked via a phosphodiester bond to a guanosine base. We report here on the crystal structure of the Hmd apoenzyme from Methanocaldococcus jannaschii at 1.75 A and from Methanopyrus kandleri at 2.4 A resolution. Homodimeric Hmd reveals a unique architecture composed of one central and two identical peripheral globular units. The central unit is composed of the intertwined C-terminal segments of both subunits, forming a novel intersubunit fold. The two peripheral units consist of the N-terminal domain of each subunit. The Rossmann fold-like structure of the N-terminal domain contains a mononucleotide-binding site, which could harbour the GMP moiety of the cofactor. Another binding site for the iron-containing cofactor is most probably Cys176, which is located at the bottom of a deep intersubunit cleft and which has been shown to be essential for enzyme activity. Adjacent to the iron of the cofactor modelled as a ligand to Cys176, an extended U-shaped extra electron density, interpreted as a polyethyleneglycol fragment, suggests a binding site for the substrate methenyltetrahydromethanopterin.
About this Structure
2B0J is a Single protein structure of sequence from Methanocaldococcus jannaschii. Full crystallographic information is available from OCA.
Reference
The crystal structure of the apoenzyme of the iron-sulphur cluster-free hydrogenase., Pilak O, Mamat B, Vogt S, Hagemeier CH, Thauer RK, Shima S, Vonrhein C, Warkentin E, Ermler U, J Mol Biol. 2006 May 5;358(3):798-809. Epub 2006 Mar 2. PMID:16540118 Page seeded by OCA on Sat May 3 19:42:05 2008
