中文摘要：

在发菜耐旱差异蛋白质组学研究中,发现假定蛋白（Hypothetical protein NXL-01）在干旱胁迫条件下表达量逐渐增加。根据已知氨基酸序列设计简并引物克隆NXL-01基因,长度为327bp（GenBank登录号为HM854288）。生物信息学分析表明,该基因具有较高保守性,蛋白质二级结构主要由α螺旋和随机卷曲构成,是亲水性的膜外蛋白,有5个Ser磷酸化位点,1个Thr磷酸化位点。将NXL-01基因在大肠杆菌中表达,获得预期大小的重组蛋白（12.4kD）。RT-PCR分析表明,NXL-01mRNA在干旱胁迫条件下表达量逐渐增加,与NXL-01蛋白的表达趋势一致。

英文摘要：

Nostoc flagelliforme is a kind of terrestrial nitrogen-fixing cyanobacteria being strong drought ecologieal adaptability. An unknown protein related to drought-tolerant, named hypothetical protein NXL- 01,has been discovered by the proteornic analysis under drought stress. NXL-O1 gene was cloned by designed degeneracy primers based on identified amino acid sequences. A full length of 327 bp DNA was obtained（GenBank access number： HM854288）. Bioinformatics analysis showed that the NXL-01 gene was highly conservative. The secondary structure of NXL-01 was made up of a helix and random eoil. It was a hydrophilic outside membrane protein with five Ser phosphorylation sites and one Thr phosphorylation site. NXL-O1 was expressed in E. coli,and a 12.4 kD heterologous protein was observed. RT-PCR showed that mRNA level of NXL-01 gradually increased, consistent with the expression trend of NXL-01 in N. flagelliforme under drought stress.