title: Contribution of arginase to manganese metabolism of Aspergillus niger.
abstract: Aspects of manganese metabolism during normal and acidogenic growth of Aspergillus niger were explored. Arginase from this fungus was a Mn[II]-enzyme. The contribution of the arginase protein towards A. niger manganese metabolism was investigated using arginase knockout (D-42) and arginase over-expressing (ΔXCA-29) strains of A. niger NCIM 565. The Mn[II] contents of various mycelial fractions were found in the order: D-42 strain < parent strain < ΔXCA-29 strain. While the soluble fraction forms 60% of the total mycelial Mn[II] content, arginase accounted for a significant fraction of this soluble Mn[II] pool. Changes in the arginase levels affected the absolute mycelial Mn[II] content but not its distribution in the various mycelial fractions. The A. niger mycelia harvested from acidogenic growth media contain substantially less Mn[II] as compared to those from normal growth media. Nevertheless, acidogenic mycelia harbor considerable Mn[II] levels and a functional arginase. Altered levels of mycelial arginase protein did not significantly influence citric acid production. The relevance of arginase to cellular Mn[II] pool and homeostasis was evaluated and the results suggest that arginase regulation could occur via manganese availability.
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
authors.forename: Sarita
authors.initials: S
authors.lastname: Keni
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India. nsp@iitb.ac.in.
authors.forename: Narayan S
authors.initials: NS
authors.lastname: Punekar
mesh_terms: D001119:Arginase / Q000235:genetics / Q000378:metabolism*; D001234:Aspergillus niger / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D019343:Citric Acid / Q000378:metabolism; D003470:Culture Media; D055786:Gene Knockout Techniques; D007477:Ions / Q000378:metabolism; D008345:Manganese / Q000378:metabolism*; D025282:Mycelium / Q000254:growth & development / Q000378:metabolism
chemical_list: D003470:Culture Media; D007477:Ions; D019343:Citric Acid; D008345:Manganese; D001119:Arginase
keywords: Acidogenic growth; Arginase; Aspergillus niger; Manganese metabolism