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Publication Abstract from PubMed

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 A 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 Zn(2+) 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.

Crystal structure of Thermotoga maritima 0065, a member of the IclR transcriptional factor family.,Zhang RG, Kim Y, Skarina T, Beasley S, Laskowski R, Arrowsmith C, Edwards A, Joachimiak A, Savchenko A J Biol Chem. 2002 May 24;277(21):19183-90. Epub 2002 Mar 4. PMID:11877432^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.