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Journal of Bacteriology, January 2009, p. 249-260, Vol. 191, No. 1
0021-9193/09/$08.00+0     doi:10.1128/JB.01259-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

An Essential DnaB Helicase of Bacillus anthracis: Identification, Characterization, and Mechanism of Action{triangledown}

Esther E. Biswas,1,2 Marjorie H. Barnes,3 Donald T. Moir,3 and Subhasis B. Biswas1*

Department of Molecular Biology, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084,1 Program in Biotechnology, Department of Bioscience Technologies, Thomas Jefferson University, Philadelphia, Pennsylvania 19107,2 Microbiotix, Inc., Worcester, Massachusetts 016053

Received 8 September 2008/ Accepted 6 October 2008

We have described a novel essential replicative DNA helicase from Bacillus anthracis, the identification of its gene, and the elucidation of its enzymatic characteristics. Anthrax DnaB helicase (DnaBBA) is a 453-amino-acid, 50-kDa polypeptide with ATPase and DNA helicase activities. DnaBBA displayed distinct enzymatic and kinetic properties. DnaBBA has low single-stranded DNA (ssDNA)-dependent ATPase activity but possesses a strong 5'->3' DNA helicase activity. The stimulation of ATPase activity appeared to be a function of the length of the ssDNA template rather than of ssDNA binding alone. The highest specific activity was observed with M13mp19 ssDNA. The results presented here indicated that the ATPase activity of DnaBBA was coupled to its migration on an ssDNA template rather than to DNA binding alone. It did not require nucleotide to bind ssDNA. DnaBBA demonstrated a strong DNA helicase activity that required ATP or dATP. Therefore, DnaBBA has an attenuated ATPase activity and a highly active DNA helicase activity. Based on the ratio of DNA helicase and ATPase activities, DnaBBA is highly efficient in DNA unwinding and its coupling to ATP consumption.

* Corresponding author. Mailing address: Department of Molecular Biology, UMDNJ-SOM, 2 Medical Center Dr., Stratford, NJ 08084. Phone: (856) 566-6270. Fax: (856) 424-1558. E-mail: subhasis.biswas{at}umdnj.edu

{triangledown} Published ahead of print on 17 October 2008.

Journal of Bacteriology, January 2009, p. 249-260, Vol. 191, No. 1
0021-9193/09/$08.00+0     doi:10.1128/JB.01259-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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