Biologia, Bratislava, 57/Suppl. 11: 109-118, 2002.

ISSN 0006-3088 (Biologia).


Full Paper

A structural model for the N-terminal N1 module of E. coli glycogen branching enzyme.


Leila Lo Leggio1*, Heidi A. Ernst1, Ida Hilden2 & Sine Larsen1

1 Centre for Crystallographic Studies, Chemistry Institute, Universitetsparken 5, DK-2100 Copenhagen N, Denmark; tel.: ++ 45 35320295, fax: ++ 45 35320299, e-mail:

2 Danisco Cultor Innovation, Langebrogade 1, DK-1001 Copenhagen K, Denmark (current address: M&E Biotech, Kogle Alle 6, DK-2970 Hørsholm, Denmark)

* corresponding author

Received: November 2, 2001 / Accepted: February 12, 2002



Prokaryotic branching enzymes can be divided into Group 1, with long N-domains, and Group 2, with short N-domains. Sequence analysis and fold-recognition approaches suggest that in Group 1 enzymes the N-domain has originated from duplication of a module with an immunoglobulin-type fold, similar in fold to the N-domain found in some other family 13 enzymes. These modules are here referred to as N1 and N2. Group 2 enzymes only have one such module. A three-dimensional model of the N1 module of E. coli GBE, a Group 1 branching enzyme, has been constructed based on secondary structure alignment to the N-domains of Pseudomonas amyloderamosa isoamylase and Sulfolobus solfataricus glycosyltrehalose trehalohydrolase.


Key words: glycogen branching enzyme, N-domain, a-amylase family, domain duplication, homology model, structure.