Ravindran Aarti, Sunderrajan Shruthi, Pennathur Gautam
Centre for Biotechnology, Anna University, Chennai, Tamil Nadu, 600 025, India.
Department of Chemical Engineering, Anna University, Chennai, Tamil Nadu, 600 025, India.
Curr Microbiol. 2019 May;76(5):597-606. doi: 10.1007/s00284-019-01665-0. Epub 2019 Mar 16.
Prodigiosin and undecylprodigiosin are tripyrrolic red pigmented antibiotics produced by certain bacteria. Many strains of Serratia and certain other Gammaproteobacteria produce prodigiosin and undecylprodigiosin is produced by certain strains of Streptomyces. This is a multistage process which involves the synthesis of a bipyrrolic compound from L-proline and its subsequent condensation with a mono pyrrole synthesized from 2-octenal in the case of prodigiosin and malonyl-CoA in the case of undecylprodigiosin respectively. We have carried out sequence analysis of the genes involved in the pathway and identified the distribution of the prodigiosin producing genes amongst the various bacteria which have been fully sequenced. The presence of the operon was clearly seen in certain clustered branches suggesting inheritance from a common ancestor. This was further confirmed by the absence of traits observed in horizontally acquired genes like, GC content variation, codon bias or the presence of mobile elements. Multiple sequence alignment of the promoter of the prodigiosin operon in seven fully sequenced Serratia marcescens strains showed excellent homology. Putative regulatory elements in this region were identified by sequence analysis studies and many of them have been found to influence pigment production. The undecylprodigiosin gene cluster on the other hand, shows homology to other gene clusters involved in the production of other pyrrole-containing antibiotics of the genus Streptomyces. This coupled with the presence of ORFs with three different promoters could indicate lateral gene transfer. Hence the evolution of undecylprodigiosin operon could be an example of convergent evolution.
灵菌红素和十一烷基灵菌红素是由某些细菌产生的三吡咯红色色素抗生素。许多粘质沙雷氏菌菌株和某些其他γ-变形菌会产生灵菌红素，而某些链霉菌菌株会产生十一烷基灵菌红素。这是一个多阶段过程，对于灵菌红素而言，该过程涉及从L-脯氨酸合成双吡咯化合物，以及随后该化合物与由2-辛烯醛合成的单吡咯缩合；对于十一烷基灵菌红素而言，则涉及与由丙二酰辅酶A合成的单吡咯缩合。我们对该途径中涉及的基因进行了序列分析，并确定了灵菌红素产生基因在已完成全序列测定的各种细菌中的分布情况。在某些聚类分支中可以清楚地看到该操纵子的存在，这表明其从共同祖先遗传而来。水平获得基因中观察到的特征（如GC含量变化、密码子偏好或移动元件的存在）的缺失进一步证实了这一点。对七个已完成全序列测定的粘质沙雷氏菌菌株中灵菌红素操纵子启动子的多序列比对显示出极好的同源性。通过序列分析研究确定了该区域的推定调控元件，并且发现其中许多元件会影响色素的产生。另一方面，十一烷基灵菌红素基因簇与链霉菌属其他含吡咯抗生素产生所涉及的其他基因簇具有同源性。这与具有三种不同启动子的开放阅读框的存在相结合，可能表明存在横向基因转移。因此，十一烷基灵菌红素操纵子的进化可能是趋同进化的一个例子。
