Zinc Release from Xenopus Transcription Factor IIIA Induced by Chemical Modifications

Zhigang Shang*, You Di Liao, Felicia Y.H. Wu, Cheng-Wen Wu Lee

*此作品的通信作者

研究成果: Article同行評審

38 引文 斯高帕斯(Scopus)

摘要

Xenopus transcription factor IIIA (TFIIIA) contains two tightly bound intrinsic Zn2+ ions that are released through treatment with either p-(hydroxymercuri)benzenesulfonate (PMPS) or diethyl pyrocarbonate (DEP) as monitored by the metallochromic indicator 4-(2-pyridylazo)resorcinol (PAR). The inactivation of TFIIIA by DEP as detected by an in vitro 5S RNA gene transcription assay was correlated with the extent of modification of histidine residues and Zn2+ release. Following reaction with PMPS, the 7S particle was dissociated into free TFIIIA and 5S RNA. This dissociation could be correlated with the extent of modification of cysteine residues as well as the Zn2+ release. The dissociation of the 7S particle was reversed by the addition of excess thiol reagent. However, the reversibility could be inhibited by EDTA, suggesting that Zn2+ was required for the binding of TFIIIA to 5S RNA. In the presence of PMPS- or DEP modified TFIIIA or Zn2+-depleted TFIIIA, the fluorescence emission maximum of the hydrophobic probe, 8-anilinonaphthalenesulfonate, was blue-shifted by 30 nm, while only less than a 10-nm blue shift was observed in the presence of either the 7S particle or TFIIIA. These results indicate that the two Zn2+ ions in TFIIIA are coordinated with the cysteine and histidine residues and are required for maintenance of the proper conformation of TFIIIA.

原文English
頁(從 - 到)9790-9795
頁數6
期刊Biochemistry
28
發行號25
DOIs
出版狀態Published - 1 1月 1989

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