Crystal structure of transaldolase B from Escherichia coli suggests a circular permutation of the alpha/beta barrel within the class I aldolase family.
Structure
; 4(6): 715-24, 1996 Jun 15.
Article
en En
| MEDLINE
| ID: mdl-8805555
ABSTRACT
BACKGROUND:
Transaldolase is one of the enzymes in the non-oxidative branch of the pentose phosphate pathway. It transfers a C3 ketol fragment from a ketose donor to an aldose acceptor. Transaldolase, together with transketolase, creates a reversible link between the pentose phosphate pathway and glycolysis. The enzyme is of considerable interest as a catalyst in stereospecific organic synthesis and the aim of this work was to reveal the molecular architecture of transaldolase and provide insights into the structural basis of the enzymatic mechanism.RESULTS:
The three-dimensional (3D) structure of recombinant transaldolase B from E. coli was determined at 1.87 A resolution. The enzyme subunit consists of a single eight-stranded alpha/beta-barrel domain. Two subunits form a dimer related by a twofold symmetry axis. The active-site residue Lys132 which forms a Schiff base with the substrate is located at the bottom of the active-site cleft.CONCLUSIONS:
The 3D structure of transaldolase is similar to structures of other enzymes in the class I aldolase family. Comparison of these structures suggests that a circular permutation of the protein sequence might have occurred in transaldolase, which nevertheless results in a similar 3D structure. This observation provides evidence for a naturally occurring circular permutation in an alpha/beta-barrel protein. It appears that such genetic permutations occur more frequently during evolution than was previously thought.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Transaldolasa
/
Estructura Secundaria de Proteína
/
Escherichia coli
Idioma:
En
Revista:
Structure
Asunto de la revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
/
BIOTECNOLOGIA
Año:
1996
Tipo del documento:
Article
País de afiliación:
Suecia