4YT2

Hmd II from Methanocaldococcus jannaschii

4YT2 の概要

• エントリーDOI: 10.2210/pdb4yt2/pdb
• 関連するPDBエントリー: 4TYE 4YT4 4YT5 4YT8
• 分子名称: H(2)-forming methylenetetrahydromethanopterin dehydrogenase-related protein MJ1338, TRIETHYLENE GLYCOL, DI(HYDROXYETHYL)ETHER, ... (4 entities in total)
• 機能のキーワード: metal binding protein, rossmann-fold, oxidoreductase
• 由来する生物種: Methanocaldococcus jannaschii
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 75166.78

構造登録者

Fujishiro, T.,Ermler, U.,Shima, S. (登録日: 2015-03-17, 公開日: 2015-07-01, 最終更新日: 2024-05-01)

主引用文献

Fujishiro, T.,Ataka, K.,Ermler, U.,Shima, S.
Towards a functional identification of catalytically inactive [Fe]-hydrogenase paralogs.
Febs J., 282:3412-3423, 2015

PubMed Abstract: [Fe]-hydrogenase (Hmd), an enzyme of the methanogenic energy metabolism, harbors an iron-guanylylpyridinol (FeGP) cofactor used for H2 cleavage. The generated hydride is transferred to methenyl-tetrahydromethanopterin (methenyl-H4MPT(+)). Most hydrogenotrophic methanogens contain the hmd-related genes hmdII and hmdIII. Their function is still elusive. We were able to reconstitute the HmdII holoenzyme of Methanocaldococcus jannaschii with recombinantly produced apoenzyme and the FeGP cofactor, which is a prerequisite for in vitro functional analysis. Infrared spectroscopic and X-ray structural data clearly indicated binding of the FeGP cofactor. Methylene-H4MPT binding was detectable in the significantly altered infrared spectra of the HmdII holoenzyme and in the HmdII apoenzyme-methylene-H4 MPT complex structure. The related binding mode of the FeGP cofactor and methenyl-H4MPT(+) compared with Hmd and their multiple contacts to the polypeptide highly suggest a biological role in HmdII. However, holo-HmdII did not catalyze the Hmd reaction, not even in a single turnover process, as demonstrated by kinetic measurements. The found inactivity can be rationalized by an increased contact area between the C- and N-terminal folding units in HmdII compared with in Hmd, which impairs the catalytically necessary open-to-close transition, and by an exchange of a crucial histidine to a tyrosine. Mainly based on the presented data, a function of HmdII as Hmd isoenzyme, H2 sensor, FeGP-cofactor storage protein and scaffold protein for FeGP-cofactor biosynthesis could be excluded. Inspired by the recently found binding of HmdII to aminoacyl-tRNA synthetases and tRNA, we tentatively consider HmdII as a regulatory protein for protein synthesis that senses the intracellular methylene-H4 MPT concentration.

PubMed: 26094576
DOI: 10.1111/febs.13351

実験手法

X-RAY DIFFRACTION (1.65 Å)