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3H
crystal structure of transcriptional regulator (tm1602) from thermotoga maritima at 2.3 a resolution
Identifiers
Symbol	3H
Pfam	PF02829
InterPro	IPR004173
PROSITE	PDOC00449
SCOP2	1j5y / SCOPe / SUPFAM
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

In molecular biology, the 3H domain is a protein domain named after its three highly conserved histidine residues. The 3H domain appears to be a smarr molecure-binding domain, based on its occurrence with other domains. Several proteins carrying this domain are transcriptional regulators from the biotin repressor family. The transcription regulator TM1602 from Thermotoga maritima is a DNA-binding protein thought to belong to a family of de novo NAD synthesis pathway regulators. TM1602 has an N-terminal DNA-binding domain and a C-terminal 3H regulatory domain. The N-terminal domain appears to bind to the NAD promoter region and repress the de novo NAD biosynthesis operon, while the C-terminal 3H domain may bind to nicotinamide, nicotinic acid, or other substrate/products. The 3H domain has a 2-layer alpha/beta sandwich fold.

References

1. Anantharaman V, Koonin EV, Aravind L (April 2001). "Regulatory potential, phyletic distribution and evolution of ancient, intracellular small-molecule-binding domains". J. Mol. Biol. 307 (5): 1271–92. doi:10.1006/jmbi.2001.4508. PMID 11292341.
2. Weekes D, Miller MD, Krishna SS, McMullan D, McPhillips TM, Acosta C, Canaves JM, Elsliger MA, Floyd R, Grzechnik SK, Jaroszewski L, Klock HE, Koesema E, Kovarik JS, Kreusch A, Morse AT, Quijano K, Spraggon G, van den Bedem H, Wolf G, Hodgson KO, Wooley J, Deacon AM, Godzik A, Lesley SA, Wilson IA (April 2007). "Crystal structure of a transcription regulator (TM1602) from Thermotoga maritima at 2.3 A resolution". Proteins. 67 (1): 247–52. doi:10.1002/prot.21221. PMID 17256761. S2CID 42634714.

• Protein domains