4bhd | pdb_00004bhd
Methanococcus jannaschii serine hydroxymethyl-transferase, apo form
Structural highlights
Function[GLYA_METJA] Catalyzes the reversible interconversion of serine and glycine with tetrahydromethanopterin (H4MPT) serving as the one-carbon carrier. The use of tetrahydrofolate (THF or H4PteGlu) as the pteridine substrate is 450-fold less efficient than that of H4MPT. Also exhibits a pteridine-independent aldolase activity toward beta-hydroxyamino acids, producing glycine and aldehydes, via a retro-aldol mechanism. Thus, is able to catalyze the cleavage of L-allo-threonine and L-threo-beta-phenylserine.[1] Publication Abstract from PubMedSerine hydroxymethyltransferases (SHMTs) play an essential role in one-carbon unit metabolism and are employed in biomimetic reactions. We determined the crystal structure of free (apo) and PLP-bound (holo) SHMT from Methanocaldococcus jannaschii, the first from a hyperthermophile, from the archaea domain of life and that uses H4 MPT as a cofactor, at 2.83 and 3.0 A resolution, respectively. Idiosyncratic features were observed that are likely to contribute to structure stabilization. At the dimer interface, the C-terminal region folds in a unique fashion with respect to SHMTs from eubacteria and eukarya. At the active site, the conserved tyrosine does not make a cation-pi interaction with an arginine like that observed in all other SHMT structures, but establishes an amide-aromatic interaction with Asn257, at a different sequence position. This asparagine residue is conserved and occurs almost exclusively in (hyper)thermophile SHMTs. This led us to formulate the hypothesis that removal of frustrated interactions (such as the Arg-Tyr cation-pi interaction occurring in mesophile SHMTs) is an additional strategy of adaptation to high temperature. Both peculiar features may be tested by designing enzyme variants potentially endowed with improved stability for applications in biomimetic processes. (c) Proteins 2014;. (c) 2014 Wiley Periodicals, Inc. The crystal structure of archaeal serine hydroxymethyltransferase reveals idiosyncratic features likely required to withstand high temperatures.,Angelucci F, Morea V, Angelaccio S, Saccoccia F, Contestabile R, Ilari A Proteins. 2014 Sep 26. doi: 10.1002/prot.24697. PMID:25257552[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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