ABSTRACT
Penicillium chrysogenum is widely used as an industrial antibiotic producer, in particular in the synthesis of ß-lactam antibiotics such as penicillins and cephalosporins. In industrial processes, oxalic acid formation leads to reduced product yields. Moreover, precipitation of calcium oxalate complicates product recovery. We observed oxalate production in glucose-limited chemostat cultures of P. chrysogenum grown with or without addition of adipic acid, side-chain of the cephalosporin precursor adipoyl-6-aminopenicillinic acid (ad-6-APA). Oxalate accounted for up to 5% of the consumed carbon source. In filamentous fungi, oxaloacetate hydrolase (OAH; EC3.7.1.1) is generally responsible for oxalate production. The P. chrysogenum genome harbours four orthologs of the A. niger oahA gene. Chemostat-based transcriptome analyses revealed a significant correlation between extracellular oxalate titers and expression level of the genes Pc18g05100 and Pc22g24830. To assess their possible involvement in oxalate production, both genes were cloned in Saccharomyces cerevisiae, yeast that does not produce oxalate. Only the expression of Pc22g24830 led to production of oxalic acid in S. cerevisiae. Subsequent deletion of Pc22g28430 in P. chrysogenum led to complete elimination of oxalate production, whilst improving yields of the cephalosporin precursor ad-6-APA.
Subject(s)
Hydrolases/genetics , Hydrolases/metabolism , Oxalates/metabolism , Penicillium chrysogenum/metabolism , beta-Lactams/metabolism , Culture Media , Fungal Proteins/genetics , Fungal Proteins/metabolism , Gene Expression Profiling , Genetic Engineering/methods , Industrial Microbiology/methods , Penicillium chrysogenum/enzymology , Penicillium chrysogenum/genetics , Penicillium chrysogenum/growth & developmentABSTRACT
HLA-B*52:21 differs from the closest, HLA-B*52:01:02, by two nucleotides (CTG â TGG), leading to an amino acid substitution from Leu to Trp at codon 156.
Subject(s)
Alleles , Amino Acid Substitution , Codon/genetics , HLA-B Antigens/genetics , Base Sequence , Brazil , Humans , Molecular Sequence DataABSTRACT
Human leucocyte antigen (HLA)-B*4509 differs from the closest HLA-B*4502 by three nucleotides that lead to changes of Tyr113His, Asn114Asp and Phe116Ser. HLA-B*5212 differs from HLA-B*520101 by a single nucleotide substitution, leading to a change of Asn114Asp.
