- Pt-barrel
The PT-barrel, is a new protein fold.
The PT-Barrel Fold
It consists of a closed β-sheet comprising ten anti-parallel β-strands arranged around a central β-barrel core, itself surrounded by a ring of α-helices forming the outer, solvent exposed surface of the barrel.
The secondary connectivity nearly conforms to an (ααββ)5 classification, but is more specifically described using the (ααββ)4-(αββ)−α nomenclature, where helices 6 and 8, both involved in inter-protein contacts in the crystal lattice, display a helical “kink”. The most hydrophobic section of the PT-barrel is the region residing between the outer surface of the cylindrical β-barrel and the belt of surrounding α-helices. Additionally, a number of hydrophobic residues located inside the barrel accommodate the prenyl tail of the Geranyl-diPhosphate (GPP) and GSPP molecules, while the diphosphate or the thio-diphosphate head groups of substrate and substrate analogs, respectively, point toward the “upper”, more polar end of the barrel where a Mg2+ ion is coordinated. Finally, the bottom of the barrel is capped by a short C-terminal helix (α11).
References
* Kuzuyama T, Noel JP, Richard SB. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15959519&query_hl=1 Structural basis for the promiscuous biosynthetic prenylation of aromatic natural products] . Nature. 2005 Jun 16;435(7044):983-7.
* Koehl P. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16408001&query_hl=5&itool=pubmed_docsum Relaxed specificity in aromatic prenyltransferases] . Nat Chem Biol. 2005 Jul;1(2):71-2.
* Botta B, Delle Monache G, Menendez P, Boffi A. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16229901&query_hl=5&itool=pubmed_docsum Novel prenyltransferase enzymes as a tool for flavonoid prenylation] . Trends Pharmacol Sci. 2005 Dec;26(12):606-8. Epub 2005 Oct 17.Online Resources
[http://chembio.salk.edu/~richard/ptbarrel/ The PT-Barrel Ressource] is under construction
Press Releases
[http://www.salk.edu/news/releases/details.php?id=135 Promiscuous Catalytic Activity Possessed by Novel Enzyme Structure, June 15, 2005]
[http://www-ssrl.slac.stanford.edu/research/highlights_archive/orf2.html SSRL Science Highlight July 2005]
[http://www.lightsources.org/cms/?pid=1000618 LightSource.org Press Release Number: PR-SSRL-05-3]
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