Torisky R S, Griffin J D, Yenofsky R L, Polacco J C
Department of Biochemistry, University of Missouri-Columbia, Columbia 65211.
Mol Gen Genet. 1994 Feb;242(4):404-14. doi: 10.1007/BF00281790.
We sought to determine the genetic basis of expression of the ubiquitous (metabolic) urease of soybean. This isozyme is termed the metabolic urease because its loss, in eu4/eu4 mutants, leads to accumulation of urea, whereas loss of the embryo-specific urease isozyme does not. The eu4 lesion eliminated the expression of the ubiquitous urease in vegetative and embryonic tissues. RFLP analysis placed urease clone LC4 near, or within, the Eu4 locus. Sequence comparison of urease proteins (ubiquitous and embryo-specific) and clones (LC4 and LS1) indicated that LC4 and LS1 encode ubiquitous and embryo-specific ureases, respectively. That LC4 is transcribed into poly(A)+ RNA in all tissues was indicated by the amplification of its transcript by an LC4-specific PCR primer. (The LS1-specific primer, on the other hand, amplified poly(A)+ RNA only from developing embryos expressing the embryo-specific urease.) These observations are consistent with Eu4 being the ubiquitous urease structural gene contained in the LC4 clone. In agreement with this notion, the mutant phenotype of eu4/eu4 callus was partially corrected by the LC4 urease gene introduced by particle bombardment.
我们试图确定大豆中普遍存在的（代谢型）脲酶表达的遗传基础。这种同工酶被称为代谢型脲酶，因为在eu4/eu4突变体中其缺失会导致尿素积累，而胚胎特异性脲酶同工酶的缺失则不会。eu4损伤消除了营养组织和胚胎组织中普遍存在的脲酶的表达。限制性片段长度多态性（RFLP）分析将脲酶克隆LC4定位在Eu4基因座附近或内部。脲酶蛋白（普遍存在的和胚胎特异性的）与克隆（LC4和LS1）的序列比较表明，LC4和LS1分别编码普遍存在的和胚胎特异性的脲酶。通过LC4特异性PCR引物对其转录本进行扩增，表明LC4在所有组织中都转录为多聚腺苷酸加尾（poly(A)+）RNA。（另一方面，LS1特异性引物仅从表达胚胎特异性脲酶的发育中的胚胎中扩增出poly(A)+ RNA。）这些观察结果与Eu4是LC4克隆中包含的普遍存在的脲酶结构基因一致。与此观点一致的是，通过粒子轰击导入的LC4脲酶基因部分纠正了eu4/eu4愈伤组织的突变表型。
