Site-Specific Nickase from Bacillus Species Strain D6

L. A. Zheleznaya¹, T. A. Perevyazova¹, D. V. Alzhanova², and N. I. Matvienko^2*

¹Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia; fax: (0967) 790-553

²Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia; fax: (095) 924-0493; E-mail: nikmatv@vega.protres.ru

^* To whom correspondence should be addressed.

Received January 11, 2001; Revision received April 2, 2001

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Three site-specific endonucleases were found in thermophilic strain Bacillus species D6. One of them, BspD6II, is an isoschizomer of Eco57I. The second, BspD6III, is present in the strain in very small amount; therefore, it has not been characterized. This paper is devoted to the third, BspD6I, which recognizes pentanucleotide site 5´-GAGTC-3´ and cleaves only one DNA strand at a distance of 4 nucleotides from the site in the 3´-direction in the chain with the GAGTC sequence, i.e., it behaves as a site-specific nickase. Nickase N.BspD6I cleaves one DNA strand only in double-stranded DNA and does not cleave single-stranded DNA. Site-specific methylase SscL1I (an isohypectomer of M*HinfI) that methylates adenine in the sequence 5´-GANTC-3´ prevents DNA hydrolysis by nickase BspD6I.

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KEY WORDS: site-specific endonucleases, site-specific nickases, DNA methyltransferases

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