3OTC: Crystal Structure Of Human Trnahis Guanylyltransferase (Thg1)- Native Ii

All known DNA and RNA polymerases catalyze the formation of phosphodiester bonds in a 5' to 3' direction, suggesting this property is a fundamental feature of maintaining and dispersing genetic information. The tRNA(His) guanylyltransferase (Thg1) is a member of a unique enzyme family whose members catalyze an unprecedented reaction in biology: 3'-5' addition of nucleotides to nucleic acid substrates. The 2.3-A crystal structure of human THG1 (hTHG1) reported here shows that, despite the lack of sequence similarity, hTHG1 shares unexpected structural homology with canonical 5'-3' DNA polymerases and adenylyl/guanylyl cyclases, two enzyme families known to use a two-metal-ion mechanism for catalysis. The ability of the same structural architecture to catalyze both 5'-3' and 3'-5' reactions raises important questions concerning selection of the 5'-3' mechanism during the evolution of nucleotide polymerases.
PDB ID: 3OTCDownload
MMDB ID: 86306
PDB Deposition Date: 2010/9/11
Updated in MMDB: 2010/12
Experimental Method:
x-ray diffraction
Resolution: 3.01  Å
Source Organism:
Similar Structures:
Biological Unit for 3OTC: tetrameric; determined by author and by software (PISA)
Molecular Components in 3OTC
Label Count Molecule
Proteins (4 molecules)
tRNA(his) Guanylyltransferase(Gene symbol: THG1L)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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