2VMT

Crystal structure of Y60AbsSHMT L-Ser external aldimine

Summary for 2VMT

• Entry DOI: 10.2210/pdb2vmt/pdb
• Related: 1KKJ 1KKP 1KL1 1KL2 1YJS 1YJY 1YJZ 2VGS 2VGT 2VGU 2VGV 2VGW 2VI8 2VI9 2VIA 2VIB 2VMN 2VMO 2VMP 2VMQ 2VMR 2VMS 2VMU 2VMV 2VMW 2VMX 2VMY 2VMZ
• Descriptor: SERINE HYDROXYMETHYLTRANSFERASE, SERINE, PYRIDOXAL-5'-PHOSPHATE, ... (6 entities in total)
• Functional Keywords: plp-dependent enzymes, y60a, transferase, folate binding, pyridoxal phosphate, one-carbon metabolism
• Biological source: BACILLUS STEAROTHERMOPHILUS
• Total number of polymer chains: 1
• Total formula weight: 44747.47

Authors

Rajaram, V.,Pai, V.R.,Bisht, S.,Bhavani, B.S.,Appaji Rao, N.,Savithri, H.S.,Murthy, M.R.N. (deposition date: 2008-01-29, release date: 2008-12-16, Last modification date: 2023-12-13)

Primary citation

Pai, V.R.,Rajaram, V.,Bisht, S.,Bhavani, B.S.,Rao, N.A.,Murthy, M.R.N.,Savithri, H.S.
Structural and Functional Studies of Bacillus Stearothermophilus Serine Hydroxymethyltransferase: The Role of Asn(341), Tyr(60) and Phe(351) in Tetrahydrofolate Binding.
Biochem.J., 418:635-, 2009

PubMed Abstract: SHMT (serine hydoxymethyltransferase), a type I pyridoxal 5'-phosphate-dependent enzyme, catalyses the conversion of L-serine and THF (tetrahydrofolate) into glycine and 5,10-methylene THF. SHMT also catalyses several THF-independent side reactions such as cleavage of beta-hydroxy amino acids, transamination, racemization and decarboxylation. In the present study, the residues Asn(341), Tyr(60) and Phe(351), which are likely to influence THF binding, were mutated to alanine, alanine and glycine respectively, to elucidate the role of these residues in THF-dependent and -independent reactions catalysed by SHMT. The N341A and Y60A bsSHMT (Bacillus stearothermophilus SHMT) mutants were inactive for the THF-dependent activity, while the mutations had no effect on THF-independent activity. However, mutation of Phe(351) to glycine did not have any effect on either of the activities. The crystal structures of the glycine binary complexes of the mutants showed that N341A bsSHMT forms an external aldimine as in bsSHMT, whereas Y60A and F351G bsSHMTs exist as a mixture of internal/external aldimine and gem-diamine forms. Crystal structures of all of the three mutants obtained in the presence of L-allo-threonine were similar to the respective glycine binary complexes. The structure of the ternary complex of F351G bsSHMT with glycine and FTHF (5-formyl THF) showed that the monoglutamate side chain of FTHF is ordered in both the subunits of the asymmetric unit, unlike in the wild-type bsSHMT. The present studies demonstrate that the residues Asn(341) and Tyr(60) are pivotal for the binding of THF/FTHF, whereas Phe(351) is responsible for the asymmetric binding of FTHF in the two subunits of the dimer.

PubMed: 19046138
DOI: 10.1042/BJ20081739

Experimental method

X-RAY DIFFRACTION (1.72 Å)