Davis R, van der Lelie D, Mercenier A, Daly C, Fitzgerald G F
Department of Food Microbiology, University College, Cork, Ireland.
Appl Environ Microbiol. 1993 Mar;59(3):777-85. doi: 10.1128/aem.59.3.777-785.1993.
Two genes from the total genomic DNA of dairy starter culture Lactococcus lactis subsp. cremoris UC503, encoding ScrFI modification enzymes, have been cloned and expressed in Escherichia coli. No homology between the two methylase genes was detected, and inverse polymerase chain reaction of flanking chromosomal DNA indicated that both were linked on the Lactococcus genome. Neither clone encoded the cognate endonuclease. The DNA sequence of one of the methylase genes (encoded by pCI931M) was determined and consisted of an open reading frame 1,170 bp long, which could encode a protein of 389 amino acids (M(r), 44.5). The amino acid sequence contained the highly characteristic motifs of an m5C methylase. Extensive regions of homology were observed with the methylases of NlaX, EcoRII, and Dcm.
来自乳制品发酵剂乳酸乳球菌亚种cremoris UC503的总基因组DNA中的两个基因，编码ScrFI修饰酶，已在大肠杆菌中克隆并表达。未检测到这两个甲基化酶基因之间的同源性，侧翼染色体DNA的反向聚合酶链反应表明它们在乳酸乳球菌基因组上是相连的。两个克隆均未编码同源内切核酸酶。确定了其中一个甲基化酶基因（由pCI931M编码）的DNA序列，其由一个1170 bp长的开放阅读框组成，可编码一个由389个氨基酸组成的蛋白质（M(r)，44.5）。氨基酸序列包含m5C甲基化酶的高度特征性基序。观察到与NlaX、EcoRII和Dcm的甲基化酶有广泛的同源区域。
