Argininosuccinate synthetase and argininosuccinate lyase: two ornithine cycle enzymes from Agaricus bisporus.
Accumulation of high quantities of urea in fruiting bodies is a known feature of larger basidiomycetes. Argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL) are two ornithine cycle enzymes catalysing the last two steps in the arginine biosynthetic pathway. Arginine is the main precursor for urea formation. In this work the nucleotide sequences of the genes and corresponding cDNAs encoding argininosuccinate synthetase (ass) and argininosuccinate lyase (asl) from Agaricus bisporus were determined. Eight and six introns were present in the ass and asl gene, respectively. The location of four introns in the asl gene were conserved among vertebrate asl genes. Deduced amino acid sequences, representing the first homobasidiomycete ASS and ASL protein sequences, were analysed and compared with their counterparts in other organisms. The ass ORF encoded for a protein of 425 amino acids with a calculated molecular mass of 47266Da. An alignment with ASS proteins from other organisms revealed high similarity with fungal and mammalian ASS proteins, 61-63% and 51-55% identity, respectively. The asl open reading frame (ORF) encoded a protein of 464 amino acids with an calculated mass of 52337Da and similar to ASS shared the highest similarity with fungal ASL proteins, 59-60% identity. Northern analyses of ass and asl during fruiting body formation and post-harvest development revealed that expression was significantly up-regulated from developmental stage 3 on for all the tissues studied. The expression reached a maximum at the later stages of fruiting body growth, stages 6 and 7. Both ass and asl genes were up-regulated within 3h after harvest showing that the induction mechanism is very sensitive to the harvest event and emphasizes the importance of the arginine biosynthetic pathway/ornithine cycle in post-harvest physiology.
Wagemaker
Matthijs J M
MJ
Department of Microbiology, IWWR, Radboud University Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen, The Netherlands.
Eastwood
Daniel C
DC
van der Drift
Chris
C
Jetten
Mike S M
MS
Burton
Kerry
K
Van Griensven
Leo J L D
LJ
Op den Camp
Huub J M
HJ
D000364:Agaricus / Q000201:enzymology* / Q000254:growth & development; D000595:Amino Acid Sequence; D001123:Argininosuccinate Lyase / Q000235:genetics* / Q000378:metabolism; D001124:Argininosuccinate Synthase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009952:Ornithine / Q000378:metabolism*; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015854:Up-Regulation
D005656:Fungal Proteins; D009952:Ornithine; D001123:Argininosuccinate Lyase; D001124:Argininosuccinate Synthase