CRYSTALLIZATION AND PRELIMINARY-X-RAY STUDIES OF I-CREI - A GROUP-I INTRON-ENCODED ENDONUCLEASE FROM CHLAMYDOMONAS-REINHARDTII

Group I intron endonuclease I-CreI is encoded by an open reading frame contained within a self-splicing intron in the Chlamydomonas reinhard tii chloroplast 235 rRNA gene, I-CreI initiates the lateral transfer o r homing of this intron by specifically recognizing and cleaving a pse udopalindromic 19-24 bp homing site in chloroplast 235 rRNA genes that lack the intron. The gene encoding this enzyme has been subcloned, an d the protein product has been purified and crystallized. The crystals belong to space group P321, with unit cell dimensions a = b = 78.2 An gstrom c = 67.4 Angstrom. The crystal unit cell is consistent with an asymmetric unit consisting of the enzyme monomer. The specific volume of this unit cell is 3.3 Angstrom(3)/Da. The crystals diffract to at l east 3.0 Angstrom resolution after flash-cooling, when using a rotatin g anode x-ray source and an RAXIS image plate detector. (C) 1997 Wiley -Liss, Inc.