Cloning, expression and purification of a glycosylated form of the DNA-binding protein Dps from Salmonella enterica Typhimurium

• Published in: Protein expression and purification Vol. 59; no. 2; pp. 197 - 202
• Main Authors: Hanna, Ebert Seixas, Roque-Barreira, Maria-Cristina, Mendes, Guilherme Martines Teixeira, Soares, Sandro Gomes, Brocchi, Marcelo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-06-2008
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - isolation & purification; Bacterial Proteins - metabolism; Cloning, Molecular; DNA-Binding Proteins - genetics; DNA-Binding Proteins - isolation & purification; DNA-Binding Proteins - metabolism; Genetic Vectors - genetics; Glycosylation; Recombinant Dps; Salmonella; Salmonella enterica typhimurium; Salmonella typhimurium - genetics; Salmonella typhimurium - metabolism; Salmonella; Glycosylation; Recombinant Dps
• ISSN: 1046-5928; 1096-0279
• DOI: 10.1016/j.pep.2008.01.015

Dps, found in many eubacterial and archaebacterial species, appears to protect cells from oxidative stress and/or nutrient-limited environment. Dps has been shown to accumulate during the stationary phase, to bind to DNA non-specifically, and to form a crystalline structure that compacts and protects the chromosome. Our previous results have indicated that Dps is glycosylated at least for a certain period of the bacterial cell physiology and this glycosylation is thought to be orchestrated by some factors not yet understood, explaining our difficulties in standardizing the Dps purification process. In the present work, the open reading frame of the
dps gene, together with all the upstream regulatory elements, were cloned into a PCR cloning vector. As a result, the expression of
dps was also controlled by the plasmid system introduced in the bacterial cell. The gene was then over-expressed regardless of the growth phase of the culture and a glycosylated fraction was purified to homogeneity by lectin-immobilized chromatography assay. Unlike the high level expression of Dps in
Salmonella cells, less than 1% of the recombinant protein was purified by affinity chromatography using jacalin column. Sequencing and mass spectrometry data confirmed the identity of the
dps gene and the protein, respectively. In spite of the low level of purification of the jacalin-binding Dps, this work shall aid further investigations into the mechanism of Dps glycosylation.