Cloning and DNA sequence of sigB gene of Stigmatella aurantiaca.
Cloning and DNA sequence of sigB gene of Stigmatella aurantiaca.
复制标题
橙色臭霉sigB基因的克隆及DNA序列分析。
作者：
H. Skladny;M. Heidelbach;H. Schairer
橙黄柱头菌属于粘细菌，在环境胁迫下形成种特异性子实体，含有粘孢子。如枯草芽孢杆菌（1）所示，在发育过程中，σ因子的级联可能激活阶段特异性基因。该通讯报告了sigB基因的克隆和测序，该基因编码DNA依赖性RNA聚合酶（RNAP）的σ亚基。通过使用寡核苷酸（5 ′-CAC（GC）GCCT fCATCAGGCCG-AT-3 ′）作为杂交探针，从橙色链霉菌DNA的λ gt 11文库中分离该基因，其对应于真细菌σ因子的高度保守结构域2（2）（氨基酸IGLMKAV）。该结构域被认为参与RNAP核心结合（2），并且也应该存在于次要的σ因子中。通过桑格双脱氧法测定sigB基因的DNA序列。ORF编码296个氨基酸的多肽，预测分子量为33，297。与其他σ序列的比对表明，它属于热休克σ簇（3）。与金黄色链霉菌SigA多肽的同源性约为30%，与黄色粘球菌SigB多肽的同源性约为92%，与大肠杆菌SigB多肽的同源性约为92%。coliRpoH多肽含量约为48%。该蛋白质与其他细菌σ因子共有一些特征，即大量带电氨基酸（SigB中14%的酸性氨基酸和14%的碱性氨基酸）以及对应于各种σ因子的保守区域的结构域。SigB与
Stigmatella aurantiaca belongs to the myxobacteria, which, upon environmental stress, form species-specific fruiting bodies, containing myxospores. As shown in Bacillus subtilis (1), a cascade of sigma factors may activate stage-specific genes during development. This communication reports the cloning and sequencing of the sigB gene, encoding a sigma-subunit of the DNA dependent RNA polymerase (RNAP). The gene was isolated from a lambda gt 1l library of S.aurantiaca DNA by using an oligonucleotide (5'-CAC(GC)GCCTfCATCAGGCCG-AT-3') as a hybridization probe, which corresponds to the highly conserved domain 2 (2) of eubacterial sigma factors (amino acids IGLMKAV). This domain is thought to be involved in RNAP core binding (2) and should be present also in minor sigma factors. The DNA sequence of the sigB gene was determined by the Sanger dideoxy method. The ORF encodes a polypeptide of 296 amino acids with a predicted molecular weight of 33,297. The alignment with other sigma-sequences shows, that it belongs to the heat shock sigma cluster (3). The homology to SigA polypeptide of S.aurantiaca is about 30%, to Myxococcus xanthus SigB polypeptide about 92% and to E. coli RpoH polypeptide about 48 %. The protein shares some features common to other bacterial sigma factors, i.e. a large number of charged amino acids (14% acidic amino acids and 14% basic amino acids in SigB) as well as domains corresponding to conserved regions of various sigma factors. The alignment of SigB with