Wassenberg D, Wuhrer M, Beaucamp N, Schurig H, Wozny M, Reusch D, Fabry S, Jaenicke R
Institut für Biophysik und Physikalische Biochemie, Universität Regensburg, Germany.
Biol Chem. 2001 Apr;382(4):693-7. doi: 10.1515/BC.2001.082.
The pgk-tpi gene locus of Thermotoga maritima encodes both phosphoglycerate kinase (PGK) and a bienzyme complex consisting of a fusion protein of PGK with triosephosphate isomerase (TIM). No separate tpi gene for TIM is present in T. maritima. A frame-shift at the end of the pgk gene has been previously proposed as a mechanism to regulate the expression of the two protein variants [Schurig et al., EMBO J. 14 (1995), 442-451]. Surprisingly, the complete T. maritima genome was found to contain a pgk-tpi sequence not requiring the proposed frameshift mechanism. To clarify the apparent discrepancy, a variety of DNA sequencing techniques were applied, disclosing an anomalous local variability in the pgk-tpi fusion region. The comparison of different DNA samples and the mass spectrometric analysis of the amino acid sequence of the natural fusion protein from T. maritima MSB8 confirmed the local variability of the DNA variants. Since not all peptide masses could be assigned, further variations are conceivable, suggesting an even higher heterogeneity of the T. maritima MSB8 strain.
海栖热袍菌的pgk-tpi基因座编码磷酸甘油酸激酶（PGK）以及由PGK与磷酸丙糖异构酶（TIM）的融合蛋白组成的双酶复合物。海栖热袍菌中不存在单独的TIM的tpi基因。之前有人提出pgk基因末端的移码是调节这两种蛋白质变体表达的一种机制[Schurig等人，《欧洲分子生物学组织杂志》14（1995年），442 - 451页]。令人惊讶的是，发现海栖热袍菌的完整基因组包含一个不需要上述移码机制的pgk-tpi序列。为了阐明这一明显的差异，应用了多种DNA测序技术，揭示了pgk-tpi融合区域存在异常的局部变异性。对不同DNA样本的比较以及对海栖热袍菌MSB8天然融合蛋白氨基酸序列的质谱分析证实了DNA变体的局部变异性。由于并非所有肽质量都能被确定，所以可以想象还有其他变异，这表明海栖热袍菌MSB8菌株的异质性甚至更高。
