Fusidic and Helvolic Acid Inhibition of Elongation Factor 2 from the Archaeon Sulfolobus solfataricus

详细信息    查看全文

• 作者：Emmanuele De Vendittis ; Barbara de Paola ; Maria Angela Gogliettino ; Bianca Stella Adinolfi ; Antonio Fiengo ; Tore Duvold ; and Vincenzo Bocchini
• 刊名：Biochemistry
• 出版年：2002
• 出版时间：December 17, 2002
• 年：2002
• 卷：41
• 期：50
• 页码：14879 - 14884
• 全文大小：71K
• 年卷期：v.41,no.50(December 17, 2002)
• ISSN：1520-4995

文摘

Fusidic acid (FA) and helvolic acid (HA) belong to a small family of naturally occurringsteroidal antibiotics known as fusidanes. FA was studied for its ability to alter the biochemical propertiessupported by elongation factor 2 isolated from the archaeon Sulfolobus solfataricus (SsEF-2). Both poly(Phe) synthesis and ribosome-dependent GTPase (GTPase^r) were progressively impaired by increasingconcentrations of FA up to 1 mM, whereas no effect was measured in the intrinsic GTPase of SsEF-2triggered by ethylene glycol in the presence of barium chloride (GTPase^g). The highest antibioticconcentration caused inhibition of either poly(Phe) synthesis or GTPase^r only slightly above 50%. Agreater response of SsEF-2 was observed when HA was used instead of FA. HA caused even a weakimpairment of GTPase^g. A mutated form of SsEF-2 carrying the L452R substitution exhibited an increasedsensitivity to fusidane inhibition in either poly(Phe) synthesis or GTPase^r. Furthermore, both FA and HAwere able to cause impairment of GTPase^g. The antibiotic concentrations leading to 50% inhibition (IC₅₀)indicate that increased fusidane responsiveness due to the use of HA or the L452R amino acid replacementis mutually independent. However, their combined effect decreased the IC₅₀ up to 0.1 mM. Despite thedifficulties in reaching complete inhibition of the translocation process in S. solfataricus, these findingssuggest that fusidane sensibility is partially maintained in the archaeon S. solfataricus. Therefore, it islikely that SsEF-2 harbors the structural requirements for forming complexes with fusidane antibiotics.This hypothesis is further evidenced by the observed low level of impairment of GTPase^g, a findingsuggesting a weak direct interaction between the archaeal factor and fusidanes even in the absence of theribosome. However, the ribosome remains essential for the sensitivity of SsEF-2 toward fusidane antibiotics.