English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/24652
Share/Impact:
Statistics
logo share SHARE   Add this article to your Mendeley library MendeleyBASE
Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:

Title

Rat liver betaine-homocysteine S-methyltransferase equilibrium unfolding: insights into intermediate structure through tryptophan substitutions

AuthorsGarrido, Francisco ; Gasset, M. ; Sanz-Aparicio, J. ; Alfonso, Carlos ; Pajares, María A.
KeywordsBetaine–homocysteine methyltransferase folding
Monomeric intermediate
Tetrameric intermediate
Triosephosphate isomerase (TIM) barrel
Tryptophan fluorescence
Issue Date1-Nov-2005
PublisherBiochemical Society
CitationBiochemical Journal 391(3): 589-599 (2005)
AbstractEquilibrium folding of rat liver BHMT (betaine-homocysteine methyltransferase), a TIM (triosephosphate isomerase)-barrel tetrameric protein, has been studied using urea as denaturant. A combination of activity measurements, tryptophan fluorescence, CD and sedimentation-velocity studies suggested a multiphasic process including two intermediates, a tetramer (I4) and a monomer (J). Analysis of denaturation curves for single- and six-tryptophan mutants indicated that the main changes leading to the tetrameric intermediate are related to alterations in the helix alpha4 of the barrel, as well as in the dimerization arm. Further dissociation to intermediate J included changes in the loop connecting the C-terminal alpha-helix of contact between dimers, disruption of helix alpha4, and initial alterations in helix alpha7 of the barrel, as well as in the dimerization arm. Evolution of the monomeric intermediate continued through additional perturbations in helix alpha7 of the barrel and the C-terminal loop. Our data highlight the essential role of the C-terminal helix in dimer-dimer binding through its contribution to the increased stability shown by BHMT as compared with other TIM barrel proteins. The results are discussed in the light of the high sequence conservation shown by betaine-homocysteine methyltransferases and the knowledge available for other TIM-barrel proteins.
Description11 pages, 7 figures, 4 tables.
Publisher version (URL)http://www.biochemj.org/bj/391/0589/bj3910589.htm
URIhttp://hdl.handle.net/10261/24652
ISSN0264-6021
Appears in Collections:(IQFR) Artículos
(IIBM) Artículos
(CIB) Artículos
Files in This Item:
File Description SizeFormat 
accesoRestringido.pdf15,38 kBAdobe PDFThumbnail
View/Open
Show full item record
Review this work
 


WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.