Publications

• An evolutionary conserved d-galacturonic acid metabolic pathway operates across filamentous fungi capable of pectin degradation.

  Martens-Uzunova E.S., Schaap P.J.

  Transcriptome analysis of Aspergillus niger transfer cultures grown on galacturonic acid media identified a highly correlating cluster of four strongly induced hypothetical genes linked with a subset set of genes encoding pectin degrading enzymes. Three of the encoded hypothetical proteins now des ... >> More

  Transcriptome analysis of Aspergillus niger transfer cultures grown on galacturonic acid media identified a highly correlating cluster of four strongly induced hypothetical genes linked with a subset set of genes encoding pectin degrading enzymes. Three of the encoded hypothetical proteins now designated GAAA to GAAC are directly involved in further galacturonic acid catabolism. Functional and biochemical analysis revealed that GAAA is a novel d-galacturonic acid reductase. Two non-allelic Aspergillus nidulans strains unable to utilize galacturonic acid are mutated in orthologs of gaaA and gaaB, respectively. The A. niger gaaA and gaaC genes share a common promoter region. This feature appears to be strictly conserved in the genomes of plant cell wall degrading fungi from subphylum Pezizomycotina. Combined with the presence of homologs of the gaaB gene in the same set of fungi, these strongly suggest that a common d-galacturonic acid utilization pathway is operative in these species. << Less

  Fungal Genet. Biol. 45:1449-1457(2008) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• The missing link in the fungal D-galacturonate pathway: identification of the L-threo-3-deoxy-hexulosonate aldolase.

  Hilditch S., Berghall S., Kalkkinen N., Penttila M., Richard P.

  The fungal path for the catabolism of D-galacturonate is only partially known. It is however distinctly different to the well-known bacterial path. The known elements of the fungal path are D-galacturonate reductase converting D-galacturonate to L-galactonate and L-galactonate dehydratase converti ... >> More

  The fungal path for the catabolism of D-galacturonate is only partially known. It is however distinctly different to the well-known bacterial path. The known elements of the fungal path are D-galacturonate reductase converting D-galacturonate to L-galactonate and L-galactonate dehydratase converting L-galactonate to L-threo-3-deoxy-hexulosonate (2-keto-3-deoxy-L-galactonate). Here we describe the missing link in this pathway, an aldolase converting L-threo-3-deoxy-hexulosonate to pyruvate and L-glyceraldehyde. Fungal enzymes converting L-glyceraldehyde to glycerol have been described previously. The L-threo-3-deoxy-hexulosonate aldolase activity was induced in the mold Hypocrea jecorina (Trichoderma reesei) during growth on D-galacturonate. The enzyme was purified from this mold and a partial amino acid sequence obtained. This sequence was then used to identify the corresponding gene from the H. jecorina genome. The deletion of the gene resulted in a strain unable to grow on d-galacturonate and accumulating L-threo-3-deoxy-hexulosonate. The open reading frame was cloned from cDNA and functionally expressed in the yeast Saccharomyces cerevisiae. A histidine-tagged protein was expressed, purified, and characterized. The enzyme catalyzed reaction was reversible. With L-threo-3-deoxy-hexulosonate as substrate the K(m) was 3.5 mM and with pyruvate and L-glyceraldehyde the K(m) were 0.5 and 1.2 mM, respectively. << Less

  J. Biol. Chem. 282:26195-26201(2007) [PubMed] [EuropePMC]