The crystal structure of the apoenzyme of the iron-sulphur cluster-free hydrogenase |
| |
Authors: | Pilak Oliver Mamat Björn Vogt Sonja Hagemeier Christoph H Thauer Rudolf K Shima Seigo Vonrhein Clemens Warkentin Eberhard Ermler Ulrich |
| |
Affiliation: | Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universit?t, Marburg, Karl-von-Frisch Strasse D-35043 Marburg, Germany. |
| |
Abstract: | 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. |
| |
Keywords: | hydrogenases iron-containing cofactor tetrahydromethanopterin crystal structure Rossmann fold |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|