PDBsum entry 1bkp

Methyltransferase

PDB id: 1bkp

Contents

Protein chains

278 a.a. *

Waters ×349

* Residue conservation analysis

PDB id:

1bkp

Name:

Methyltransferase

Title:

Thermostable thymidylate synthase a from bacillus subtilis

Structure:

Thymidylate synthase a. Chain: a, b. Engineered: yes

Source:

Bacillus subtilis. Organism_taxid: 1423. Cell_line: x2913. Gene: thya. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_cell_line: x2913.

Biol. unit:

Dimer (from PQS)

Resolution:

1.70Å R-factor: 0.151 R-free: 0.206

Authors:

T.J.Stout,U.Schellenberger,D.V.Santi,R.M.Stroud

Key ref:

T.J.Stout et al. (1998). Crystal structures of a unique thermal-stable thymidylate synthase from Bacillus subtilis. Biochemistry, 37, 14736-14747. PubMed id: 9778348 DOI: 10.1021/bi981270l

Date:

09-Jul-98 Release date: 02-Feb-99

Protein chains

P0CI79  (TYSY1_BACSU) -  Thymidylate synthase 1 from Bacillus subtilis (strain 168)

Seq: 279 a.a.

Struc: 278 a.a.

Enzyme reactions

• Enzyme class: E.C.2.1.1.45 - thymidylate synthase.
• Pathway: Folate Coenzymes
• Reaction: dUMP + (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate = 7,8-dihydrofolate + dTMP

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1021/bi981270l

Biochemistry 37:14736-14747 (1998)

PubMed id: 9778348

Crystal structures of a unique thermal-stable thymidylate synthase from Bacillus subtilis.

T.J.Stout, U.Schellenberger, D.V.Santi, R.M.Stroud.

ABSTRACT

Unlike all other organisms studied to date, Bacillus subtilis expresses two different thymidylate synthases: bsTS-A and bsTS-B. bsTS-A displays enhanced enzymatic and structural thermal stability uncharacteristic of most TSs. Despite the high level of TS conservation across most species, bsTS-A shares low sequence identity (<40%) with the majority of TSs from other organisms. This TS and the TSs from Lactococcus lactis and phage Phi3T-to which it is most similar-have been of interest for some time since, by structure-based sequence alignment, they appear to lack several key residues shown by mutagenesis to be essential to enzymatic function [Greene, P. J., Yu, P. L., Zhao, J., Schiffer, C. A., and Santi, D. (1994) Protein Sci. 3, 1114-6]. In addition, bsTS-A demonstrates specific activity 2-3-fold higher than TS from Lactobacillus casei or Escherichia coli. We have solved the crystal structure of this unusual TS in four crystal forms to a maximum resolution of 1.7 A. Each of these crystal forms contains either one or two noncrystallographically related dimers. Stabilization of the beta-sheet dimer interface through a dramatic architecture of buttressed internal salt bridges maintains the structural integrity of bsTS-A at elevated temperatures. Melting curves of TSs from L. casei and E. coli are compared to that of TS-A from B. subtilis and correlated with numbers of hydrogen bonds, salt bridges, and the numbers of interactions localized to the dimer interface. Analysis of this structure will shed light on the conservation of function across diversity of sequence, as well as provide insights into the thermal stabilization of a highly conserved enzyme.