Purification of overexpressed hexahistidine-tagged BLM N431 as oligomeric complexes

Sergey F. Beresten, Rodica Stan, Anja J. Van Brabant, Tian Ye, Saule Naureckiene, Nathan A. Ellis

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


BLM is a DNA helicase encoded by a gene which is mutated in persons with Bloom's syndrome. The protein is a member of the RecQ subfamily of helicases and contains a central domain constituted by the seven motifs conserved in all helicases. In contrast, the N-terminal portion of BLM lacks similarity to any other known proteins or motifs. We have expressed the first 431 amino acids of this domain as a fusion to a hexahistidine tag (BLM N431) in Escherichia coli. A method of purification was developed which involves elution from Ni-NTA resin in imidazole and EDTA, followed by treatment with DTT and gel filtration on Sephacryl-300. The treatment with EDTA and DTT prevents and disrupts aggregation of BLM N431. The purified protein appears to form hexamers and dodecamers, suggesting that the N-terminal domain of BLM is involved in the organization of the quaternary structure of BLM.

Original languageEnglish (US)
Pages (from-to)239-248
Number of pages10
JournalProtein Expression and Purification
Issue number2
StatePublished - Nov 1999

ASJC Scopus subject areas

  • Biotechnology


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