Gao Weixia, Xie Yaya, Zuo Meng, Zhang Guangtong, Liu Hao
MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457 People's Republic of China.
Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science and Technology, Tianjin, 300457 People's Republic of China.
3 Biotech. 2022 Sep;12(9):192. doi: 10.1007/s13205-022-03227-x. Epub 2022 Jul 26.
, group C Streptococci, is currently used for the industrial production of hyaluronic acid (HA). However, genetic manipulation of is severely limited by its low transformation efficiency, which might be in part due to the Restriction-Modification (R-M) systems. The complete genome sequence of ATCC39920 revealed the presence of two putative R-M systems, type I and type II. The putative type I R-M system is encoded by three closely linked genes: (), , (), and the putative type II R-M system consists of two closely linked genes: and (). Inactivation of encoding the restriction endonuclease (REase) of the type I R-M system, showed no apparent effects on transformation efficiency, implying that disarmament of the type I R-M system alone is not sufficient for increasing transformation efficiency. However, inactivation of , encoding the REase of the type II R-M system, improved transformation efficiency by 4.97 folds, indicating that type II R-M system is the major barrier that restricts genetic transformation in . Furthermore, strains lacking either of the two R-M systems are phenotypically indistinguishable from the wild-type in terms of cell growth and HA production. In summary, our study revealed that the type II R-M system is the main barrier to genetic transformation in ATCC39920, and that the deletion of the type II R-M system renders more transformable, thus facilitating metabolic engineering of this industrially important microorganism.
The online version contains supplementary material available at 10.1007/s13205-022-03227-x.
C 组链球菌目前用于透明质酸（HA）的工业生产。然而，其低转化效率严重限制了对其的基因操作，这可能部分归因于限制修饰（R-M）系统。ATCC39920 的全基因组序列揭示了存在两种推定的 R-M 系统，I 型和 II 型。推定的 I 型 R-M 系统由三个紧密连锁的基因编码：（）、（）、（），推定的 II 型 R-M 系统由两个紧密连锁的基因组成：（）和（）。编码 I 型 R-M 系统限制内切酶（REase）的（）失活对转化效率没有明显影响，这意味着仅消除 I 型 R-M 系统不足以提高转化效率。然而，编码 II 型 R-M 系统 REase 的（）失活使转化效率提高了 4.97 倍，表明 II 型 R-M 系统是限制（）中基因转化的主要障碍。此外，缺乏这两种 R-M 系统之一的（）菌株在细胞生长和 HA 生产方面与野生型在表型上没有区别。总之，我们的研究表明 II 型 R-M 系统是 ATCC39920 中基因转化的主要障碍，并且删除 II 型 R-M 系统使（）更易于转化，从而促进了这种工业上重要微生物的代谢工程。
在线版本包含可在 10.1007/s13205-022-03227-x 获得的补充材料。
