Tenney K, Hunt I, Sweigard J, Pounder J I, McClain C, Bowman E J, Bowman B J
Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA.
Fungal Genet Biol. 2000 Dec;31(3):205-17. doi: 10.1006/fgbi.2000.1230.
We have identified a gene, named hex-1, that encodes the major protein in the hexagonal crystals, or Woronin bodies, of Neurospora crassa. Analysis of a strain with a null mutation in the hex-1 gene showed that the septal pores in this organism were not plugged when hyphae were damaged, leading to extensive loss of cytoplasm. When grown on agar plates containing sorbose, the hex-1(-) strain showed extensive lysis of hyphal tips. The HEX-1 protein was predicted to be 19,125 Da. Analysis of the N-terminus of the purified protein indicated that 16 residues are cleaved, yielding a protein of 17,377 Da. A polyclonal antibody raised to the HEX-1 protein recognized multiple forms of the protein, apparently dimers and tetramers that were resistant to solubilization by sodium dodecyl sulfate and reducing reagents. Treatment of the protein with phosphatase caused dissociation of these oligomers. Preparations enriched in Woronin bodies contained catalase activity, which was not detected in comparable fractions from the hex-1(-) mutant strain. These results support the hypothesis that the Woronin body is a specialized peroxisome that functions as a plug for septal pores.
我们已经鉴定出一个名为hex-1的基因，它编码粗糙脉孢菌六角形晶体（即沃罗宁体）中的主要蛋白质。对hex-1基因发生无效突变的菌株进行分析表明，当菌丝受损时，该生物体中的隔膜孔未被堵塞，导致细胞质大量流失。当在含有山梨糖的琼脂平板上生长时，hex-1（-）菌株显示出菌丝尖端的广泛裂解。预测HEX-1蛋白的分子量为19,125道尔顿。对纯化蛋白N端的分析表明，有16个氨基酸残基被切割，产生了一个分子量为17,377道尔顿的蛋白。针对HEX-1蛋白产生的多克隆抗体识别该蛋白的多种形式，显然是对十二烷基硫酸钠和还原剂溶解有抗性的二聚体和四聚体。用磷酸酶处理该蛋白会导致这些寡聚体解离。富含沃罗宁体的制剂含有过氧化氢酶活性，而在hex-1（-）突变菌株的可比组分中未检测到该活性。这些结果支持了沃罗宁体是一种专门的过氧化物酶体，其功能是作为隔膜孔的堵塞物这一假说。
