Crystal structure of Thermotoga maritima 0065 - a member of the IclR transcriptional factor family
Members of the IclR family of transcription regulators modulate signal-dependent expression of genes involved in carbon metabolism in bacteria and archaea. The Thermotoga maritima TM0065 gene codes for a protein (TM-IclR) that is homologous to the IclR family. We have determined the crystal structure of TM-IclR at 2.2 Angstroms resolution using MAD phasing and synchrotron radiation. The protein is composed of two domains: the N-terminal DNA-binding domain contains the winged helix-turn-helix motif, and the C-terminal presumed regulatory domain is involved in binding signal molecule. In a proposed signal-binding site, a bound Zn2+ ion was found. In the crystal, TM-IclR forms a dimer through interactions between DNA-binding domains. In the dimer, the DNA-binding domains are 2-fold related, but the dimer is asymmetric with respect to the orientation of signal-binding domains. Crystal packing analysis showed that TM-IclR dimers form a tetramer through interactions exclusively by signal-binding domains. A model is proposed for binding of IclR-like factors to DNA, and it suggests that signal-dependent transcription regulation is accomplished by affecting an oligomerization state of IclR and therefore its affinity for DNA target.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- NIH; FOR; SC
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 949514
- Report Number(s):
- ANL/BIO/JA-41656
- Journal Information:
- J. Biol. Chem., Journal Name: J. Biol. Chem. Journal Issue: 21 ; May 24, 2002 Vol. 277; ISSN JBCHA3; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- ENGLISH
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