文献类型： 外文期刊

作者： Zhu, Derui ¹ ; Liu, Jian ¹ ; Han, Rui ³ ; Shen, Guoping ² ; Long, Qifu ² ; Wei, Xiaoxing ² ; Liu, Deli ¹ ;

作者机构： 1.Cent China Normal Univ, Coll Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China

2.Qinghai Univ, Res Ctr Basic Med Sci, Coll Med, Xining 810016, Peoples R China

3.Qinghai Univ, Qinghai Acad Agr Forestry Sci, Xining 810016, Peoples R China

关键词： Halomonas;compatible solutes;ectoine;ectABC gene cluster;cloning and expression

期刊名称：JOURNAL OF MICROBIOLOGY （ 影响因子：3.422； 五年影响因子：3.28 ）

ISSN： 1225-8873

年卷期： 2014 年 52 卷 2 期

页码：

收录情况： SCI

摘要： The moderately halophilic bacterium Halomonas sp. QHL1 was identified as a member of the genus Halomonas by 16S rRNA gene sequencing. HPLC analysis showed that strain QHL1 synthesizes ectoine in its cytoplasm. The genes involved in the ectoine biosynthesis pathway were identified on the chromosome in the order ectABC. Subsequently, the ectB gene from this strain was amplified by PCR, and the entire ectABC gene cluster (3,580 bp) was cloned using genome walking. Analysis showed that the ectA (579 bp), ectB (1269 bp), and ectC (390 bp) genes were organized in a single transcriptional unit and were predicted to encode three peptides of 21.2 kDa, 46.4 kDa, and 14.7 kDa, respectively. Two putative promoters, a delta(70)-dependent promoter and a delta(38)-controlled promoter, as well as several conserved motifs with unknown function were identified. Individual ectA, ectB, and ectC genes, and the entire ectABC gene cluster were inserted into the expression plasmid pET-28a(+) to generate the recombinant plasmids pET-28a(+)-ectA, pET-28a(+)-ectB, pET-28a(+)-ectC and pET-28a(+)-ectABC, respectively. Heterologous expression of these proteins in Escherichia coli BL21 (DE3) was confirmed by SDS-PAGE. The recombinant E. coli strain BL21 (pET-28a (+)-ectABC) displayed a higher salt tolerance than native E. coli cells but produced far less ectoine than the wild-type QHL1 strain.