English
 
User Manual Privacy Policy Disclaimer Contact us
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  On the structural basis of the catalytic mechanism and the regulation of the alpha subunit of tryptophan synthase from Salmonella typhimurium and BX1 from maize, two evolutionarily related enzymes

Kulik, V., Hartmann, E., Weyand, M., Frey, M., Gierl, A., Niks, D., et al. (2005). On the structural basis of the catalytic mechanism and the regulation of the alpha subunit of tryptophan synthase from Salmonella typhimurium and BX1 from maize, two evolutionarily related enzymes. Journal of Molecular Biology (London), 352(3), 608-620. doi:10.1016/j.jmb.2005.07.014.

Item is

Basic

show hide
Item Permalink: http://hdl.handle.net/11858/00-001M-0000-002A-C30A-5 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-002A-C30B-3
Genre: Journal Article
Alternative Title : On the structural basis of the catalytic mechanism and the regulation of the alpha subunit of tryptophan synthase from Salmonella typhimurium and BX1 from maize, two evolutionarily related enzymes

Files

show Files
hide Files
:
JMolBiol_352_2005_352.pdf (Any fulltext), 546KB
 
File Permalink:
-
Name:
JMolBiol_352_2005_352.pdf
Description:
-
Visibility:
Restricted (Max Planck Institute for Medical Research, MHMF; )
MIME-Type / Checksum:
application/pdf
Technical Metadata:
Copyright Date:
-
Copyright Info:
-
License:
-

Creators

show
hide
 Creators:
Kulik, Victor1, Author              
Hartmann, Elisabeth1, Author              
Weyand, Michael, Author
Frey, Marco2, Author              
Gierl, Alfons, Author
Niks, Dimitri, Author
Dunn, Michael F., Author
Schlichting, Ilme1, Author              
Affiliations:
1Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Max Planck Society, ou_1497700              
2Department of Molecular Neurobiology, Max Planck Institute for Medical Research, Max Planck Society, ou_1497704              

Content

show
hide
Free keywords: crystal structure; enzymatic mechanism; transition state analogue; sstructure-function-relationship; TIM barrel
 Abstract: Indole is a reaction intermediate in at least two biosynthetic pathways in maize seedlings. In the primary metabolism, the alpha-subunit (TSA) of the bifunctional tryptophan synthase (TRPS) catalyzes the cleavage of indole 3-glycerol phosphate (IGP) to indole and d-glyceraldehyde 3-phosphate (G3P). Subsequently, indole diffuses through the connecting tunnel to the beta-active site where it is condensed with serine to form tryptophan and water. The maize enzyme, BX1, a homolog of TSA, also cleaves IGP to G3P and indole, and the indole is further converted to 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one, a secondary plant metabolite. BX1 cleaves IGP significantly faster to G3P and indole than does TSA. In line with their different biological functions, these two evolutionary related enzymes differ significantly in their regulatory aspects while catalyzing the same chemistry. Here, the mechanism of IGP cleavage by TSA was analyzed using a novel transition state analogue generated in situ by reaction of 2-aminophenol and G3P. The crystal structure of the complex shows an sp3-hybridized atom corresponding to the C3 position of IGP. The catalytic alphaGlu49 rotates to interact with the sp3-hybridized atom and the 3' hydroxyl group suggesting that it serves both as proton donor and acceptor in the alpha-reaction. The second catalytic residue, alphaAsp60 interacts with the atom corresponding to the indolyl nitrogen, and the catalytically important loop alphaL6 is in the closed, high activity conformation. Comparison of the TSA and TSA-transition state analogue structures with the crystal structure of BX1 suggests that the faster catalytic rate of BX1 may be due to a stabilization of the active conformation: loop alphaL6 is closed and the catalytic glutamate is in the active conformation. The latter is caused by a substitution of the residues that stabilize the inactive conformation in TRPS.

Details

show
hide
Language(s): eng - English
 Dates: 2005-07-032005-05-132005-07-062005-08-022005-09-23
 Publication Status: Published in print
 Pages: 13
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Journal of Molecular Biology (London)
  Other : J Mol Biol
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: London : Academic Press
Pages: - Volume / Issue: 352 (3) Sequence Number: - Start / End Page: 608 - 620 Identifier: ISSN: 0022-2836
CoNE: https://pure.mpg.de/cone/journals/resource/954922646042