De Vendittis Emmanuele, De Paola Barbara, Gogliettino Maria Angela, Adinolfi Bianca Stella, Fiengo Antonio, Duvold Tore, Bocchini Vincenzo
Dipartimento di Biochimica e Biotecnologie Mediche, Università di Napoli Federico II, via S. Pansini, 5, Italy.
Biochemistry. 2002 Dec 17;41(50):14879-84. doi: 10.1021/bi026743+.
Fusidic acid (FA) and helvolic acid (HA) belong to a small family of naturally occurring steroidal antibiotics known as fusidanes. FA was studied for its ability to alter the biochemical properties supported 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 increasing concentrations of FA up to 1 mM, whereas no effect was measured in the intrinsic GTPase of SsEF-2 triggered by ethylene glycol in the presence of barium chloride (GTPase(g)). The highest antibiotic concentration caused inhibition of either poly(Phe) synthesis or GTPase(r) only slightly above 50%. A greater response of SsEF-2 was observed when HA was used instead of FA. HA caused even a weak impairment of GTPase(g). A mutated form of SsEF-2 carrying the L452R substitution exhibited an increased sensitivity to fusidane inhibition in either poly(Phe) synthesis or GTPase(r). Furthermore, both FA and HA were able to cause impairment of GTPase(g). The antibiotic concentrations leading to 50% inhibition (IC(50)) indicate that increased fusidane responsiveness due to the use of HA or the L452R amino acid replacement is mutually independent. However, their combined effect decreased the IC(50) up to 0.1 mM. Despite the difficulties in reaching complete inhibition of the translocation process in S. solfataricus, these findings suggest that fusidane sensibility is partially maintained in the archaeon S. solfataricus. Therefore, it is likely 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 finding suggesting a weak direct interaction between the archaeal factor and fusidanes even in the absence of the ribosome. However, the ribosome remains essential for the sensitivity of SsEF-2 toward fusidane antibiotics.
夫西地酸（FA）和黄青霉素（HA）属于一类名为夫西地烷的天然甾体抗生素小家族。研究了FA改变从古生菌嗜热栖热菌（SsEF - 2）分离的延伸因子2所支持的生化特性的能力。高达1 mM的FA浓度增加会使多聚（苯丙氨酸）合成和核糖体依赖性GTP酶（GTPase(r)）逐渐受损，而在氯化钡存在下由乙二醇触发的SsEF - 2内在GTP酶（GTPase(g)）未检测到影响。最高抗生素浓度导致多聚（苯丙氨酸）合成或GTPase(r)的抑制仅略高于50%。当使用HA代替FA时，观察到SsEF - 2有更大的反应。HA甚至对GTPase(g)有轻微损害。携带L452R替代的SsEF - 2突变形式在多聚（苯丙氨酸）合成或GTPase(r)中对夫西地烷抑制表现出更高的敏感性。此外，FA和HA都能够导致GTPase(g)受损导致50%抑制的抗生素浓度（IC(50)）表明，由于使用HA或L452R氨基酸替代导致的夫西地烷反应性增加是相互独立的。然而，它们的联合作用使IC(50)降低至0.1 mM。尽管在嗜热栖热菌中完全抑制转位过程存在困难，但这些发现表明嗜热栖热菌中部分维持了对夫西地烷的敏感性。因此，SsEF - 2可能具有与夫西地烷抗生素形成复合物的结构要求。GTPase(g)受损程度较低这一观察结果进一步证明了这一假设，这一发现表明即使在没有核糖体的情况下，古生因子与夫西地烷之间也存在微弱的直接相互作用。然而，核糖体对于SsEF - 2对夫西地烷抗生素的敏感性仍然至关重要。
