Expression, purification, crystallization and preliminary X-ray studies of the TAN1 orthologue from Methanothermobacter thermautotrophicus.

MTH909 is the Methanothermobacter thermautotrophicus orthologue of Saccharomyces cerevisiae TAN1, which is required for N(4)-acetylcytidine formation in tRNA. The protein consists of an N-terminal near-ferredoxin-like domain and a C-terminal THUMP domain. Unlike most other proteins containing the THUMP domain, TAN1 lacks any catalytic domains and has been proposed to form a complex with a catalytic protein that is capable of making base modifications. MTH909 has been cloned, overexpressed and purified. The molecule exists as a monomer in solution. X-ray data were collected to 2.85 A resolution from a native crystal belonging to space group P6(1)22 (or P6(5)22), with unit-cell parameters a = 69.9, c = 408.5 A.