Pyrococcus horikoshii была открыта в 1992 году в гидротермальном источнике на глубине 1395 метров в Тихом океане. Pyrococcus horikoshii - это термофильная анаэробная бактерия, обитает при температурах от 85 до 105 градусов, оптимум 98 градусов.
Таксономия:
Империя: Сellulata
Царство: Archaea
Тип: Euryarchaeota
Класс: Thermococci
Отряд: Thermococcales
Семейство Thermococcaceae
Род: Pyrococcus
Вид: Pyrococcus horikoshii
Геном Pyrococcus horikoshii был секвенирован для того, чтобы понять, механизмы, с помощью которых бактерия выживает в столь жестких условиях.
Статья: Mechanistic understanding of Pyrococcus horikoshii Dph2, a [4Fe-4S] enzyme required for diphthamide biosynthesis.
Авторы:Zhu X, Dzikovski B, Su X, Torelli AT, Zhang Y, Ealick SE, Freed JH, Lin H.
Аннотация: Diphthamide, the target of diphtheria toxin, is a unique posttranslational modification on eukaryotic and archaeal translation elongation factor 2 (EF2). The proposed biosynthesis of diphthamide involves three steps and we have recently found that in Pyrococcus horikoshii (P. horikoshii), the first step uses an S-adenosyl-l-methionine (SAM)-dependent [4Fe-4S] enzyme, PhDph2, to catalyze the formation of a C-C bond. Crystal structure shows that PhDph2 is a homodimer and each monomer contains three conserved cysteine residues that can bind a [4Fe-4S] cluster. In the reduced state, the [4Fe-4S] cluster can provide one electron to reductively cleave the bound SAM molecule. However, different from classical radical SAM family of enzymes, biochemical evidence suggest that a 3-amino-3-carboxypropyl radical is generated in PhDph2. Here we present evidence supporting that the 3-amino-3-carboxypropyl radical does not undergo hydrogen abstraction reaction, which is observed for the deoxyadenosyl radical in classical radical SAM enzymes. Instead, the 3-amino-3-carboxypropyl radical is added to the imidazole ring in the pathway towards the formation of the product. Furthermore, our data suggest that the chemistry requires only one [4Fe-4S] cluster to be present in the PhDph2 dimer.
Идентификатор статьи: PMID: 20931132 [PubMed - as supplied by publisher]
Найдена с помощью запроса: Pyrococcus horikoshii [TI]
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