Site-Specific Endonuclease AbaI from Azospirillum brasilense UQ 1796 is an Isoschizomer of Endonuclease BclI

E. V. Zabaznaya,¹ V. V. Nikiforov,¹ L. A. Zheleznaya,² and N. I. Matvienko^3,4

¹Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, pr. Entuziastov 13, Saratov, 410015 Russia; E-mail: root@ibppm.saratov.su

²Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (7-095) 135-62-19.

³Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (7-095) 924-04-93; E-mail: protres@sovam.com

⁴To whom correspondence should be addressed.

Submitted November 22, 1996; revision submitted December 22, 1996.

The site-specific endonuclease AbaI was isolated and purified to functional purity from the soil nitrogen-fixing bacterium Azospirillum brasilense UQ 1796. Purification included successive chromatography on columns with phosphocellulose, heparin-Sepharose, and hydroxyapatite. The purified enzyme recognizes the palindromic DNA sequence 5´-T***GATCA-3´ and cleaves it as shown by the arrow. The isolated enzyme belongs to class II restriction endonucleases and is an isoschizomer of endonuclease BclI. The enzyme AbaI is active at 26-56°C. The optimal temperature is 48°C and the optimal buffer is LRB.

KEY WORDS: site-specific endonuclease, isoschizomer, phosphocellulose, heparin-Sepharose, hydroxyapatite.

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