Thiopurine methyltransferase

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Thiopurine S-methyltransferase
Image:PBB Protein TPMT image.jpg
PDB rendering based on 2bzg.
Available structures:
For the file format that describes the 3D structures of molecules found in the Protein Data Bank, see Protein Data Bank (file format).

The Protein Data Bank (PDB) is a repository for 3-D structural data of proteins and nucleic acids. These data, typically obtained by X-ray crystallography or NMR spectroscopy, are submitted by biologists and biochemists from around the world, are released into the public domain, and can be accessed for free.

History

Founded in 1971 by Drs. Edgar Meyer and Walter Hamilton Brookhaven National Laboratory, management of the Protein Data Bank was transferred in 1998 to members of the Research Collaboratory for Structural Bioinformatics (RCSB).

The Worldwide Protein Data Bank (wwPDB) consists of organizations that act as deposition, data processing and distribution centers for PDB data. The founding members are RCSB PDB (USA), MSD-EBI (Europe) and PDBj (Japan). The BMRB (USA) group joined the wwPDB in 2006. The mission of the wwPDB is to maintain a single Protein Data Bank Archive of macromolecular structural data that is freely and publicly available to the global community.

The PDB is a key resource in structural biology and is critical to more recent work in structural genomics.

Countless derived databases and projects have been developed to integrate and classify the PDB in terms of protein structure, protein function and protein evolution.

Growth

When the PDB was originally founded it contained just 7 protein structures. Since then it has undergone an approximate exponential growth in the number of structures, which does not show any sign of falling off.

The growth rate of the PDB has been the subject of fairly extensive analysis.

Contents

As of 26 September, 2006, the database contained 39,051 released atomic coordinate entries (or "structures"), 35,767 of that proteins, the rest being nucleic acids, nucleic acid-protein complexes, and a few other molecules. About 5,000 new structures are released each year. Data are stored in the mmCIF format specifically developed for the purpose.

Note that the database stores information about the exact location of all atoms in a large biomolecule (although, usually without the hydrogen atoms, as their positions are more of a statistical estimate); if one is only interested in sequence data, i.e. the list of amino acids making up a particular protein or the list of nucleotides making up a particular nucleic acid, the much larger databases from Swiss-Prot and the International Nucleotide Sequence Database Collaboration should be used.

Statistics

As of 11 September, 2007, the "PDB Holdings List" at RCSB reported the following statistics:

Proteins Nucleic Acids Protein/NA complexes Other Total
X-ray diffraction 36223 983 1684 24 38914
NMR 5665 781 134 7 6587
Electron microscopy 105 10 38 0 153
Other 80 4 4 2 90
Total 42073 1778 1860 33 45744

Note that theoretical models are no longer accepted in the PDB.

22461 structures in the PDB have a structure factor file. 3138 structures in the PDB have an NMR restraint file.

The current breakdown of holdings is updated weekly.

File format

Through the years the PDB file format has undergone many, many changes and revisions. Its original format was dictated by the width of computer punch cards.

This legacy format has caused many problems with the format, and consequently there are 'clean-up' projects;

The MMDB uses ASN.1 (and an XML conversion of this format). The wwPDB members RCSB PDB, MSD-EBI, and PDBj are working together to make the data uniform across the archive. Some believe this to be desirable; others argue that, without a universal repository of information (i.e., a common dictionary), it is not possible to draw comparisons.

Each structure published in PDB receives a four-character alphanumeric identifier, its PDB ID. This should not be used as an identifier for biomolecules, since often several structures for the same molecule (in different environments or conformations) are contained in PDB with different PDB IDs.

If a biologist submits structure data for a protein or nucleic acid, wwPDB staff reviews and annotates the entry. The data are then automatically checked for plausibility. The source code for this validation software has been released for free. The main data base accepts only experimentally derived structures, and not theoretically predicted ones (see protein structure prediction).

Various funding agencies and scientific journals now require scientists to submit their structure data to PDB.

Viewing the data

The structural data can be used to visualize the biomolecules with appropriate software, such as VMD, RasMol, PyMOL, Jmol, MDL Chime, QuteMol, web browser VRML plugin or any web-based software designed to visualize and analyse the protein structures such as STING. A recent desktop software addition is Sirius. The RCSB PDB website also contains resources for education, structural genomics, and related software.

References

Printed

  • H.M. Berman, K. Henrick, H. Nakamura (2003): Announcing the worldwide Protein Data Bank. Nature Structural Biology 10 (12), p. 980 PMID 14634627.
  • H.M. Berman, J. Westbrook, Z. Feng, G. Gilliland, T.N. Bhat, H. Weissig, I.N. Shindyalov, P.E. Bourne: The Protein Data Bank. Nucleic Acids Research, 28 pp. 235-242 (2000). PMID 10592235
  • Bernstein FC, Koetzle TF, Williams GJ, Meyer Jr EF, Brice MD, Rodgers JR, Kennard O, Shimanouchi T, Tasumi M. The Protein Data Bank: a computer-based archival file for macromolecular structures. J Mol Biol 1977;112:535-542. PMID 875032.
  • E.F. Meyer “The First Years of the Protein Data Bank“, Protein Science 6:1591-1597 (1997)
  • Sussman, JL, Lin, D, Jiang, J, Manning, NO, Prilusky, J, Ritter, O & Abola, EE. Protein data bank (PDB): a database of 3D structural information of biological macromolecules. Acta Cryst 1998; D54:1078-1084. PMID 10089483.

Online

Other external links

Links to enzyme database data

  • [1] The best mapping is provided by Kim Henrick's group at EBI as part of the MSD SIFTS initiative.
  • [2] PDB provide a mapping on their beta site, but it is at the whole PDB level not chain level.
  • [3] Search at BRENDA enzyme database portal.
  • [4] PDBSProtEC:

Molecular graphic visualisation tools

The Protein Data Bank (PDB) is a repository for 3-D structural data of proteins and nucleic acids. These data, typically obtained by X-ray crystallography or NMR spectroscopy, are submitted by biologists and biochemists from around the world, are released into the public domain, and can be accessed for free.

History

Founded in 1971 by Drs. Edgar Meyer and Walter Hamilton Brookhaven National Laboratory, management of the Protein Data Bank was transferred in 1998 to members of the Research Collaboratory for Structural Bioinformatics (RCSB).

The Worldwide Protein Data Bank (wwPDB) consists of organizations that act as deposition, data processing and distribution centers for PDB data. The founding members are RCSB PDB (USA), MSD-EBI (Europe) and PDBj (Japan). The BMRB (USA) group joined the wwPDB in 2006. The mission of the wwPDB is to maintain a single Protein Data Bank Archive of macromolecular structural data that is freely and publicly available to the global community.

The PDB is a key resource in structural biology and is critical to more recent work in structural genomics.

Countless derived databases and projects have been developed to integrate and classify the PDB in terms of protein structure, protein function and protein evolution.

Growth

When the PDB was originally founded it contained just 7 protein structures. Since then it has undergone an approximate exponential growth in the number of structures, which does not show any sign of falling off.

The growth rate of the PDB has been the subject of fairly extensive analysis.

Contents

As of 26 September, 2006, the database contained 39,051 released atomic coordinate entries (or "structures"), 35,767 of that proteins, the rest being nucleic acids, nucleic acid-protein complexes, and a few other molecules. About 5,000 new structures are released each year. Data are stored in the mmCIF format specifically developed for the purpose.

Note that the database stores information about the exact location of all atoms in a large biomolecule (although, usually without the hydrogen atoms, as their positions are more of a statistical estimate); if one is only interested in sequence data, i.e. the list of amino acids making up a particular protein or the list of nucleotides making up a particular nucleic acid, the much larger databases from Swiss-Prot and the International Nucleotide Sequence Database Collaboration should be used.

Statistics

As of 11 September, 2007, the "PDB Holdings List" at RCSB reported the following statistics:

Proteins Nucleic Acids Protein/NA complexes Other Total
X-ray diffraction 36223 983 1684 24 38914
NMR 5665 781 134 7 6587
Electron microscopy 105 10 38 0 153
Other 80 4 4 2 90
Total 42073 1778 1860 33 45744

Note that theoretical models are no longer accepted in the PDB.

22461 structures in the PDB have a structure factor file. 3138 structures in the PDB have an NMR restraint file.

The current breakdown of holdings is updated weekly.

File format

Through the years the PDB file format has undergone many, many changes and revisions. Its original format was dictated by the width of computer punch cards.

This legacy format has caused many problems with the format, and consequently there are 'clean-up' projects;

The MMDB uses ASN.1 (and an XML conversion of this format). The wwPDB members RCSB PDB, MSD-EBI, and PDBj are working together to make the data uniform across the archive. Some believe this to be desirable; others argue that, without a universal repository of information (i.e., a common dictionary), it is not possible to draw comparisons.

Each structure published in PDB receives a four-character alphanumeric identifier, its PDB ID. This should not be used as an identifier for biomolecules, since often several structures for the same molecule (in different environments or conformations) are contained in PDB with different PDB IDs.

If a biologist submits structure data for a protein or nucleic acid, wwPDB staff reviews and annotates the entry. The data are then automatically checked for plausibility. The source code for this validation software has been released for free. The main data base accepts only experimentally derived structures, and not theoretically predicted ones (see protein structure prediction).

Various funding agencies and scientific journals now require scientists to submit their structure data to PDB.

Viewing the data

The structural data can be used to visualize the biomolecules with appropriate software, such as VMD, RasMol, PyMOL, Jmol, MDL Chime, QuteMol, web browser VRML plugin or any web-based software designed to visualize and analyse the protein structures such as STING. A recent desktop software addition is Sirius. The RCSB PDB website also contains resources for education, structural genomics, and related software.

References

Printed

  • H.M. Berman, K. Henrick, H. Nakamura (2003): Announcing the worldwide Protein Data Bank. Nature Structural Biology 10 (12), p. 980 PMID 14634627.
  • H.M. Berman, J. Westbrook, Z. Feng, G. Gilliland, T.N. Bhat, H. Weissig, I.N. Shindyalov, P.E. Bourne: The Protein Data Bank. Nucleic Acids Research, 28 pp. 235-242 (2000). PMID 10592235
  • Bernstein FC, Koetzle TF, Williams GJ, Meyer Jr EF, Brice MD, Rodgers JR, Kennard O, Shimanouchi T, Tasumi M. The Protein Data Bank: a computer-based archival file for macromolecular structures. J Mol Biol 1977;112:535-542. PMID 875032.
  • E.F. Meyer “The First Years of the Protein Data Bank“, Protein Science 6:1591-1597 (1997)
  • Sussman, JL, Lin, D, Jiang, J, Manning, NO, Prilusky, J, Ritter, O & Abola, EE. Protein data bank (PDB): a database of 3D structural information of biological macromolecules. Acta Cryst 1998; D54:1078-1084. PMID 10089483.

Online

Other external links

Links to enzyme database data

  • [5] The best mapping is provided by Kim Henrick's group at EBI as part of the MSD SIFTS initiative.
  • [6] PDB provide a mapping on their beta site, but it is at the whole PDB level not chain level.
  • [7] Search at BRENDA enzyme database portal.
  • [8] PDBSProtEC:

Molecular graphic visualisation tools

Identifiers
Symbol(s) TPMT;
External IDs OMIM: 187680 MGI: 98812 Homologene: 313
RNA expression pattern

Image:PBB GE TPMT 203671 at tn.png

Image:PBB GE TPMT 203672 x at tn.png

More reference expression data

Orthologs
Human Mouse
Entrez 7172 22017
Ensembl ENSG00000137364 ENSMUSG00000021376
Uniprot P51580 O55060
Refseq NM_000367 (mRNA)
NP_000358 (protein) 		NM_016785 (mRNA)
NP_058065 (protein)
Location Chr 6: 18.24 - 18.26 Mb Chr 13: 47.04 - 47.05 Mb
Pubmed search [9] [10]
Image:Thiopurine methyltransferase.png
Thiopurine methyltransferase, drawn from PDB 2BZG.

Thiopurine methyltransferase or thiopurine S-methyltransferase (TPMT) is an enzyme (EC 2.1.1.67) that methylates thiopurine compounds. The methyl donor is S-adenosyl-L-methionine, which is converted to S-adenosyl-L-homocysteine.


This gene encodes the enzyme that metabolizes thiopurine drugs via S-adenosyl-L-methionine as the S-methyl donor and S-adenosyl-L-homocysteine as a byproduct. Thiopurine drugs such as 6-mercaptopurine are used as chemotherapeutic agents. Genetic polymorphisms that affect this enzymatic activity are correlated with variations in sensitivity and toxicity to such drugs within individuals. A pseudogene for this locus is located on chromosome 18q.[1]


Pharmacology

TPMT is best known for its role in the metabolism of the drugs 6-mercaptopurine, azathioprine and 6-thioguanine. TPMT catalyzes the S-methylation of thiopurine drugs, including 6MP. Defects in the TPMT gene leads to decreased methylation and decreased inactivation of 6MP leading to enhanced bone marrow toxicity. [1]

Diagnostic use

Measurement of TPMT activity is encouraged prior to commencing azathioprine or 6-mercaptopurine, as patients with low activity (10% prevalence) or especially absent activity (prevalence 0.3%) are at a heightened risk of drug-induced bone marrow toxicity due to accumulation of the unmetabolised drug. Reuther et al found that about 5% of all thiopurine therapies will fail due to toxicity. This intolerant group could be anticipated by routine measurement of TPMT activity. There appears to be a great deal of variation in TPMT mutation, with ethnic differences in mutation types accounting for variable responses to 6MP[1].

References

Further reading

  • Reuther LO, Vainer B, Sonne J, Larsen NE. Thiopurine methyltransferase (TPMT) genotype distribution in azathioprine-tolerant and -intolerant patients with various disorders. The impact of TPMT genotyping in predicting toxicity. Eur J Clin Pharmacol 2004;59:797-801. PMID 14634700.
  • Krynetski EY, Tai HL, Yates CR, et al. (1997). "Genetic polymorphism of thiopurine S-methyltransferase: clinical importance and molecular mechanisms.". Pharmacogenetics 6 (4): 279-90. PMID 8873214.
  • Krynetski E, Evans WE (2003). "Drug methylation in cancer therapy: lessons from the TPMT polymorphism.". Oncogene 22 (47): 7403-13. doi:10.1038/sj.onc.1206944. PMID 14576848.
  • Corominas H, Baiget M (2004). "Clinical utility of thiopurine S-methyltransferase genotyping.". American journal of pharmacogenomics : genomics-related research in drug development and clinical practice 4 (1): 1-8. PMID 14987117.
  • Krynetskiy EY, Evans WE (2005). "Closing the gap between science and clinical practice: the thiopurine S-methyltransferase polymorphism moves forward.". Pharmacogenetics 14 (7): 395-6. PMID 15226671.
  • Coulthard SA, Matheson EC, Hall AG, Hogarth LA (2005). "The clinical impact of thiopurine methyltransferase polymorphisms on thiopurine treatment.". Nucleosides Nucleotides Nucleic Acids 23 (8-9): 1385-91. PMID 15571264.
  • Lee W, Lockhart AC, Kim RB, Rothenberg ML (2005). "Cancer pharmacogenomics: powerful tools in cancer chemotherapy and drug development.". Oncologist 10 (2): 104-11. doi:10.1634/theoncologist.10-2-104. PMID 15709212.
  • Pierik M, Rutgeerts P, Vlietinck R, Vermeire S (2006). "Pharmacogenetics in inflammatory bowel disease.". World J. Gastroenterol. 12 (23): 3657-67. PMID 16773681.
  • Lee D, Szumlanski C, Houtman J, et al. (1995). "Thiopurine methyltransferase pharmacogenetics. Cloning of human liver cDNA and a processed pseudogene on human chromosome 18q21.1.". Drug Metab. Dispos. 23 (3): 398-405. PMID 7628307.
  • Krynetski EY, Schuetz JD, Galpin AJ, et al. (1995). "A single point mutation leading to loss of catalytic activity in human thiopurine S-methyltransferase.". Proc. Natl. Acad. Sci. U.S.A. 92 (4): 949-53. PMID 7862671.
  • Honchel R, Aksoy IA, Szumlanski C, et al. (1993). "Human thiopurine methyltransferase: molecular cloning and expression of T84 colon carcinoma cell cDNA.". Mol. Pharmacol. 43 (6): 878-87. PMID 8316220.
  • Glauser TA, Nelson AN, Zembower DE, et al. (1993). "Diethyldithiocarbamate S-methylation: evidence for catalysis by human liver thiol methyltransferase and thiopurine methyltransferase.". J. Pharmacol. Exp. Ther. 266 (1): 23-32. PMID 8392551.
  • Szumlanski C, Otterness D, Her C, et al. (1996). "Thiopurine methyltransferase pharmacogenetics: human gene cloning and characterization of a common polymorphism.". DNA Cell Biol. 15 (1): 17-30. PMID 8561894.
  • Tai HL, Krynetski EY, Yates CR, et al. (1996). "Thiopurine S-methyltransferase deficiency: two nucleotide transitions define the most prevalent mutant allele associated with loss of catalytic activity in Caucasians.". Am. J. Hum. Genet. 58 (4): 694-702. PMID 8644731.
  • Yates CR, Krynetski EY, Loennechen T, et al. (1997). "Molecular diagnosis of thiopurine S-methyltransferase deficiency: genetic basis for azathioprine and mercaptopurine intolerance.". Ann. Intern. Med. 126 (8): 608-14. PMID 9103127.
  • Tai HL, Krynetski EY, Schuetz EG, et al. (1997). "Enhanced proteolysis of thiopurine S-methyltransferase (TPMT) encoded by mutant alleles in humans (TPMT*3A, TPMT*2): mechanisms for the genetic polymorphism of TPMT activity.". Proc. Natl. Acad. Sci. U.S.A. 94 (12): 6444-9. PMID 9177237.
  • Otterness D, Szumlanski C, Lennard L, et al. (1997). "Human thiopurine methyltransferase pharmacogenetics: gene sequence polymorphisms.". Clin. Pharmacol. Ther. 62 (1): 60-73. doi:10.1016/S0009-9236(97)90152-1. PMID 9246020.
  • Leipold G, Schütz E, Haas JP, Oellerich M (1997). "Azathioprine-induced severe pancytopenia due to a homozygous two-point mutation of the thiopurine methyltransferase gene in a patient with juvenile HLA-B27-associated spondylarthritis.". Arthritis Rheum. 40 (10): 1896-8. doi:<1896::AID-ART26>3.0.CO;2-A 10.1002/1529-0131(199710)40:10<1896::AID-ART26>3.0.CO;2-A. PMID 9336428.
  • Krynetski EY, Fessing MY, Yates CR, et al. (1998). "Promoter and intronic sequences of the human thiopurine S-methyltransferase (TPMT) gene isolated from a human PAC1 genomic library.". Pharm. Res. 14 (12): 1672-8. PMID 9453052.
  • Spire-Vayron de la Moureyre C, Debuysère H, Sabbagh N, et al. (1998). "Detection of known and new mutations in the thiopurine S-methyltransferase gene by single-strand conformation polymorphism analysis.". Hum. Mutat. 12 (3): 177-85. doi:<177::AID-HUMU5>3.0.CO;2-E 10.1002/(SICI)1098-1004(1998)12:3<177::AID-HUMU5>3.0.CO;2-E. PMID 9711875.


External links


Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .

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