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A more recent version of this article appeared on August 1, 2004
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Submitted on April 16, 2004
Revised on May 28, 2004
Accepted on June 1, 2004
-Glucanase Agn1p in Fission-Yeast Cell Separation

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*Department of Biochemistry, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
Bijvoet Center, Department of Bio-Organic Chemistry, Section of Glycoscience and Biocatalysis, Utrecht University, 3584 CH Utrecht, The Netherlands
Monitoring Editor: John Pringle
Cell division in the fission yeast Schizosaccharomyces pombe yields two equal-sized daughter cells. Medial fission is achieved by deposition of a primary septum flanked by two secondary septa within the dividing cell. During the final step of cell division, cell separation, the primary septum is hydrolyzed by an endo-(1,3)-
-glucanase, Eng1p. We reasoned that the cell-wall material surrounding the septum, referred to here as the septum edging, must also be hydrolyzed before full separation of the daughter cells can occur. As the septum edging contains (1,3)-
-glucan, we investigated the cellular functions of the putative (1,3)-
-glucanases Agn1p and Agn2p. While agn2 deletion results in a defect in endolysis of the ascus wall, deletion of agn1 leads to clumped cells that remained attached to each other by septum-edging material. Purified Agn1p hydrolyzes (1,3)-
-glucan predominantly into pentasaccharides, indicating an endo-catalytic mode of hydrolysis. Furthermore, we show that the transcription factors Sep1p and Ace2p regulate both eng1 and agn1 expression in a cell-cycle-dependent manner. We propose that Agn1p acts in concert with Eng1p to achieve efficient cell separation, thereby exposing the secondary septa as the new ends of the daughter cells.
Present address: Department of Molecular Cell Biology and Immunology, Vrije Universiteit Medical Center Amsterdam, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
Corresponding author. E-mail: f.hochstenbach{at}amc.uva.nl