Oguiza J A, Marcos A T, Malumbres M, Martín J F
Department of Ecology, Genetics and Microbiology, Faculty of Biology, University of León, Spain.
Gene. 1996 Oct 24;177(1-2):103-7. doi: 10.1016/0378-1119(96)00283-1.
The galE gene of Brevibacterium lactofermentum, encoding UDP-galactose 4-epimerase (EC 5.1.3.2), has been identified by DNA sequencing downstream from the orf1-sigB-dmdR region. The arrangement of the sigB-dtxR-galE cluster is also conserved in Corynebacterium diphtheriae. The deduced galE product was a protein of 329 aa residues (35.4 kDa) that shared a high degree of identity to known UDP-galactose 4-epimerase proteins from Gram-positive microorganisms (Streptomyces lividans and Streptococcus thermophilus). Transcriptional analysis of the dmdR and galE genes in nutrient-rich medium showed that these genes are part of an operon, that is actively transcribed as a bicistronic mRNA during the exponential growth phase, but transcription of the operon is decreased during the stationary growth phase. In addition, the dmdR gene was also expressed as a monocistronic 0.7-kb transcript during the active growth phase.
通过对orf1-sigB-dmdR区域下游进行DNA测序，已鉴定出乳酸发酵短杆菌的galE基因，该基因编码UDP-半乳糖4-差向异构酶（EC 5.1.3.2）。sigB-dtxR-galE基因簇的排列在白喉棒状杆菌中也保守。推导的galE产物是一个由329个氨基酸残基组成的蛋白质（35.4 kDa），与革兰氏阳性微生物（淡紫链霉菌和嗜热链球菌）中已知的UDP-半乳糖4-差向异构酶蛋白具有高度同源性。在营养丰富的培养基中对dmdR和galE基因进行转录分析表明，这些基因是一个操纵子的一部分，在指数生长期作为双顺反子mRNA被积极转录，但在稳定生长期操纵子的转录减少。此外，dmdR基因在活跃生长期也作为一个0.7 kb的单顺反子转录本表达。
