Mateos L M, del Real G, Aguilar A, Martín J F
Mol Gen Genet. 1987 Mar;206(3):361-7. doi: 10.1007/BF00428872.
Five DNA fragments carrying the thrB gene (homoserine kinase E.C. 2.7.1.39) of Brevibacterium lactofermentum were cloned by complementation of Escherichia coli thrB mutants using pBR322 as vector. All the cloned fragments contained a common 3.1 kb DNA sequence. The cloned fragments hybridized among themselves and with a 9 kb BamHI fragment of the chromosomal DNA of B. lactofermentum but not with the DNA of E. coli. None of the cloned fragments were able to complement thrA and thrC mutations of E. coli. Plasmids pULTH2, pULTH8 and pULTH11 had the cloned DNA fragments in the same orientation and were very stable. On the contrary, plasmid pULTH18 was very unstable and showed the DNA inserted in the opposite direction. E. coli minicells transformed with plasmids pULTH8 or pULTH11 (both carrying the common 3.1 kb fragment) synthesize a protein with an Mr of 30,000 that is similar in size to the homoserine kinase of E. coli.
以pBR322为载体，通过互补大肠杆菌thrB突变体，克隆了5个携带乳酸发酵短杆菌thrB基因（高丝氨酸激酶，E.C. 2.7.1.39）的DNA片段。所有克隆片段都含有一个共同的3.1 kb DNA序列。这些克隆片段之间以及与乳酸发酵短杆菌染色体DNA的一个9 kb BamHI片段杂交，但不与大肠杆菌的DNA杂交。没有一个克隆片段能够互补大肠杆菌的thrA和thrC突变。质粒pULTH2、pULTH8和pULTH11具有相同方向的克隆DNA片段，并且非常稳定。相反，质粒pULTH18非常不稳定，并且显示DNA以相反方向插入。用质粒pULTH8或pULTH11（两者都携带共同的3.1 kb片段）转化的大肠杆菌微小细胞合成一种Mr为30,000的蛋白质，其大小与大肠杆菌的高丝氨酸激酶相似。
