An alternative, arginase‐independent pathway for arginine metabolism in K luyveromyces lactis involves guanidinobutyrase as a key enzyme

摘要: Most available knowledge on fungal arginine metabolism is derived from studies Saccharomyces cerevisiae, in which catabolism initiated by releasing urea via the arginase reaction. Orthologues of S. cerevisiae genes encoding first three enzymes pathway were cloned Kluyveromyces lactis and shown to functionally complement corresponding deletion cerevisiae. Surprisingly, single K. gene KlCAR1 did not completely abolish growth as nitrogen source. Growth rate mutant strongly increased during serial transfer shake-flask cultures. A combination RNAseq-based transcriptome analysis 13C-15N-based flux was used elucidate arginase-independent pathway. Isotopic 13C15N-enrichment γ-aminobutyrate revealed succinate entry point TCA cycle alternative Transcript combined with enzyme activity measurements indicated expression Klcar1Δ a guanidinobutyrase (EC.3.5.3.7), key new for degradation. Expression KLLA0F27995g (renamed KlGBU1) enabled use guanidinobutyrate sole source its almost this Phylogenetic suggests that widespread fungi.