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  • 标题:Induced nucleotide specificity in a GTPase
  • 本地全文:下载
  • 作者:Shu-ou Shan ; Peter Walter
  • 期刊名称:Proceedings of the National Academy of Sciences
  • 印刷版ISSN:0027-8424
  • 电子版ISSN:1091-6490
  • 出版年度:2003
  • 卷号:100
  • 期号:8
  • 页码:4480-4485
  • DOI:10.1073/pnas.0737693100
  • 语种:English
  • 出版社:The National Academy of Sciences of the United States of America
  • 摘要:In signal-recognition particle (SRP)-dependent protein targeting to the bacterial plasma membrane, two GTPases, Ffh (a subunit of the bacterial SRP) and FtsY (the bacterial SRP receptor), act as GTPase activating proteins for one another. The molecular mechanism of this reciprocal GTPase activation is poorly understood. In this work, we show that, unlike other GTPases, free FtsY exhibits only low preference for GTP over other nucleotides. On formation of the SRP*FtsY complex, however, the nucleotide specificity of FtsY is enhanced 103-fold. Thus, interactions with SRP must induce conformational changes that directly affect the FtsY GTP-binding site: in response to SRP binding, FtsY switches from a nonspecific "open" state to a "closed" state that provides discrimination between cognate and noncognate nucleotides. We propose that this conformational change leads to more accurate positioning of the nucleotide and thus could contribute to activation of FtsY's GTPase activity by a novel mechanism.
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