Disease relevance of PUT1

• Sequence analysis of an Arabidopsis cDNA clone, ERD5 (for early responsive to dehydration stress), isolated from plants dehydrated for 1 hr, revealed that it encodes a protein with identity to products of the yeast PUT1 (for proline utilization) gene (23.6% over 364 amino acids) and the Drosophila sluggish-A gene (34.5% over 255 amino acids) [1].
• The B. japonicum gene codes for a bifunctional protein with proline dehydrogenase and pyrroline-5-carboxylate (P5C) dehydrogenase activities, as it does in Escherichia coli and Salmonella typhimurium [2].
• We report here the cloning and sequencing of the gene for proline dehydrogenase (putA) of Bradyrhizobium japonicum [2].
• Overexpression of Put1p results in low proline levels and hypersensitivity to oxidants, such as hydrogen peroxide and paraquat [3].

High impact information on PUT1

• The Arabidopsis thaliana proline dehydrogenase (ProDH) is catalysing the first step in proline degradation [4].
• Put3p is constitutively bound to the promoters of its target genes, PUT1 and PUT2, under all conditions studied but activates transcription to the maximum extent only in the absence of rich nitrogen sources and in the presence of proline (i.e., when proline serves as the sole source of nitrogen) [5].
• The PUT1 and PUT2 genes encoding the enzymes of the proline utilization pathway of Saccharomyces cerevisiae are induced by proline and activated by the product of the PUT3 gene [6].
• Deletion analysis of the two PUT1 UASs showed that they were functionally independent and additive in producing maximal levels of gene expression [6].
• By using a PUT1-lacZ gene fusion that makes a cytoplasmic beta-galactosidase, the regulation of the PUT1 gene was studied [7].

Biological context of PUT1

• The PUT1 gene was mapped distal to the GAL2 gene on chromosome XII by tetrad analysis [8].
• Comparison of PUT gene expression in cells grown in repressing or derepressing nitrogen sources, in the absence of the inducer proline, indicated that both PUT1 and PUT2 are regulated by nitrogen repression, although the effect on PUT2 is comparatively small [9].
• The PUT1 DNA was present in a single copy in the yeast genome and encoded a transcript of ca. 1.5 kb [8].
• The PUT1 gene of Saccharomyces cerevisiae, believed to encode proline oxidase, has been completely sequenced and contains an open reading frame capable of encoding a polypeptide of 476 amino acids in length [7].
• Plasmids containing the PUT1 gene restored regulated levels of proline oxidase activity to put1 recipient strains [8].

Associations of PUT1 with chemical compounds

• Although these strains were Put- and made no detectable proline oxidase activity, PUT1 message was detected under inducing conditions [8].
• In Saccharomyces cerevisiae, the PUT1-encoded proline oxidase and the PUT2-encoded delta1-pyrroline-5-carboxylate dehydrogenase are required to convert proline to glutamate [10].
• Reciprocal regulation of delta 1-pyrroline-5-carboxylate synthetase and proline dehydrogenase genes controls proline levels during and after osmotic stress in plants [11].
• The central part of P. putida PutA showed homology to the proline dehydrogenase of Saccharomyces cerevisiae and Drosophila melanogaster, whereas the C-terminal end was homologous to the pyrroline-5-carboxylate dehydrogenase of S. cerevisiae and a number of aldehyde dehydrogenases [12].

Other interactions of PUT1

• Recessive mutations in URE2 elevated expression of the PUT1 and PUT2 genes 5- to 10-fold when cells were grown on a nitrogen-repressing medium [9].
• A yeast strain carrying the previously identified put3 regulatory mutation that caused constitutive levels of proline oxidase activity was found to have sevenfold elevated PUT1 mRNA levels under noninducing conditions [8].
• We found that Nil1p and Put3p, but not Gln3p, play major roles in rapamycin-induced PUT1 expression [13].
• Molecular and genetic mapping positioned the cha4 locus 17 cM centromere proximal to put1 on chromosome XII [14].
• We constructed a novel sake yeast strain by disrupting the PUT1 gene, which is required for L-proline utilization, and replacing the wild-type PRO1 allele with the pro1(D154N) allele [15].

Analytical, diagnostic and therapeutic context of PUT1

• When cultured in liquid minimal medium, the proline-nonutilizing mutant containing the put1 mutation (proline oxidase-deficient) produced more intracellular proline, and increased the cell survival rate as compared to the wild-type strain after freezing and desiccation [16].

References