Brandriss M C, Magasanik B
J Bacteriol. 1979 Nov;140(2):498-503. doi: 10.1128/jb.140.2.498-503.1979.
Proline is converted to glutamate in the yeast Saccharomyces cerevisiae by the sequential action of two enzymes, proline oxidase and delta 1-pyrroline-5-carboxylate (P5C) dehydrogenase. The levels of these enzymes appear to be controlled by the amount of proline in the cell. The capacity to transport proline is greatest when the cell is grown on poor nitrogen sources, such as proline or urea. Mutants have been isolated which can no longer utilize proline as the sole source of nitrogen. Mutants in put1 are deficient in proline oxidase, and those in put2 lack P5C dehydrogenase. The put1 and put2 mutations are recessive, segregate 2:2 in tetrads, and appear to be unlinked to one another. Proline induces both proline oxidase and P5C dehydrogenase. The arginine-degradative pathway intersects the proline-degradative pathway at P5C. The P5C formed from the breakdown of arginine or ornithine can induce both proline-degradative enzymes by virtue of its conversion to proline.
在酿酒酵母中，脯氨酸通过脯氨酸氧化酶和δ1-吡咯啉-5-羧酸（P5C）脱氢酶的相继作用转化为谷氨酸。这些酶的水平似乎受细胞内脯氨酸含量的控制。当细胞在贫氮源（如脯氨酸或尿素）上生长时，脯氨酸的转运能力最强。已分离出不再能将脯氨酸用作唯一氮源的突变体。put1突变体缺乏脯氨酸氧化酶，put2突变体缺乏P5C脱氢酶。put1和put2突变是隐性的，并在四分体中以2:2分离，且彼此似乎不连锁。脯氨酸可诱导脯氨酸氧化酶和P5C脱氢酶。精氨酸降解途径与脯氨酸降解途径在P5C处相交。由精氨酸或鸟氨酸分解产生的P5C可因其转化为脯氨酸而诱导两种脯氨酸降解酶。
