Structure of the Escherichia coli Response Regulator NarL
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- 作者：Igor Baikalov ; Imke Schrö ; der ; Maria Kaczor-Grzeskowiak ; Kazimierz Grzeskowiak ; Robert P. Gunsalus ; and Richard E. Dickerson
- 刊名：Biochemistry
- 出版年：1996
- 出版时间：August 27, 1996
- 年：1996
- 卷：35
- 期：34
- 页码：11053 - 11061
- 全文大小：667K
- 年卷期：v.35,no.34(August 27, 1996)
- ISSN：1520-4995
文摘
The crystal structure analysis of the NarL protein provides afirst look at interactions betweenreceiver and effector domains of a full-length bacterial responseregulator. The N-terminal receiver domain,with 131 amino acids, is folded into a 5-strand 
sheet flanked by 5
helices, as seen in CheY and in theN-terminal domain of NTRC. The C-terminal DNA-binding domain, with62 amino acids, is a compactbundle of 4 helices, of which the middle 2 form ahelix-turn-helix motif closely related to that ofDrosophila paired protein and other H-T-HDNA-binding proteins. The 2 domains are connected byan helix of 10 amino acids and a 13-residue flexible tether that isnot visible and presumably disorderedin the X-ray structure. In this unphosphorylated form of NarL, theC-terminal domain is turned againstthe receiver domain in a manner that would preclude DNA binding.Activation of NarL via phosphorylationof Asp59 must involve transfer of information to the interdomaininterface and either rotation ordisplacement of the DNA-binding C-terminal domain. Docking of aB-DNA duplex against the isolatedC-terminal domain in the manner observed in paired proteinand other H-T-H proteins suggests astereochemical basis for DNA sequence preference: T-R-C-C-Y (highaffinity) or T-R-C-T-N (low affinity),which is close to the experimentally observed consensus sequence:T-A-C-Y-N. The NarL structure isa model for other members of the FixJ or LuxR family of bacterialtranscriptional activators, and possiblyto the more distant OmpR and NtrC families as well.
sheet flanked by 5 helices, as seen in CheY and in theN-terminal domain of NTRC. The C-terminal DNA-binding domain, with62 amino acids, is a compactbundle of 4 helices, of which the middle 2 form ahelix-turn-helix motif closely related to that ofDrosophila paired protein and other H-T-HDNA-binding proteins. The 2 domains are connected byan helix of 10 amino acids and a 13-residue flexible tether that isnot visible and presumably disorderedin the X-ray structure. In this unphosphorylated form of NarL, theC-terminal domain is turned againstthe receiver domain in a manner that would preclude DNA binding.Activation of NarL via phosphorylationof Asp59 must involve transfer of information to the interdomaininterface and either rotation ordisplacement of the DNA-binding C-terminal domain. Docking of aB-DNA duplex against the isolatedC-terminal domain in the manner observed in paired proteinand other H-T-H proteins suggests astereochemical basis for DNA sequence preference: T-R-C-C-Y (highaffinity) or T-R-C-T-N (low affinity),which is close to the experimentally observed consensus sequence:T-A-C-Y-N. The NarL structure isa model for other members of the FixJ or LuxR family of bacterialtranscriptional activators, and possiblyto the more distant OmpR and NtrC families as well.