Yan Xiao-hua, Liu Gang, Tan Hua-rong
Center for Microbial Genetics and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China.
Wei Sheng Wu Xue Bao. 2007 Feb;47(1):17-21.
In Bacilli, gerM is a very conservative gene. Primers were designed according to the gerM gene sequence of Bacillus cereus, and a 640bp DNA fragment was obtained from Bacillus thuringiensis subsp. kustaki 1. 175 by PCR. Using this fragment as a probe, a 4.5kb DNA fragment was cloned from the partial DNA library of Bacillus thuringiensis subsp. kustaki 1.175. Sequence analysis showed that the fragment contains one complete open reading frame (ORF) that encodes a 349-amino acid (aa) protein, which has high homology with GerM protein from Bacillus subtilis. This gene was designated gerM (GenBank Accession No. DQ537381 ) . RT-PCR analysis showed that gerM gene was only expressed in the process of sporulation, suggesting gerM is not required for the vegetative growth. The function of the gerM gene was studied by a strategy of gene disruption, and the resulting gerM disruption mutant did show normal growth and sporulation. However, gerM disruption mutant spores germinate slower than wild-type spores when triggered by L-alanine or inosine, indicating that gerM is required for the spore normal germination initiated by L-alanine or inosine in Bacillus thuringiensis.
在芽孢杆菌中，gerM是一个非常保守的基因。根据蜡样芽孢杆菌的gerM基因序列设计引物，通过PCR从苏云金芽孢杆菌库斯塔克亚种1.175中获得了一个640bp的DNA片段。以该片段为探针，从苏云金芽孢杆菌库斯塔克亚种1.175的部分DNA文库中克隆到一个4.5kb的DNA片段。序列分析表明，该片段包含一个完整的开放阅读框（ORF），编码一个349个氨基酸的蛋白质，与枯草芽孢杆菌的GerM蛋白具有高度同源性。该基因被命名为gerM（GenBank登录号：DQ537381）。RT-PCR分析表明，gerM基因仅在芽孢形成过程中表达，提示gerM对营养生长不是必需的。通过基因破坏策略研究了gerM基因的功能，所得的gerM破坏突变体确实表现出正常的生长和芽孢形成。然而，当由L-丙氨酸或肌苷触发时，gerM破坏突变体的孢子比野生型孢子萌发得慢，表明gerM是苏云金芽孢杆菌中由L-丙氨酸或肌苷引发的孢子正常萌发所必需的。
