title: Cloning and Genomic Organization of a Rhamnogalacturonase Gene from Locally Isolated Strain of Aspergillus niger.
abstract: The rhg gene encoding a rhamnogalacturonase was isolated from the novel strain A1 of Aspergillus niger. It consists of an ORF of 1.505 kb encoding a putative protein of 446 amino acids with a predicted molecular mass of 47 kDa, belonging to the family 28 of glycosyl hydrolases. The nature and position of amino acids comprising the active site as well as the three-dimensional structure were well conserved between the A. niger CTM10548 and fungal rhamnogalacturonases. The coding region of the rhg gene is interrupted by three short introns of 56 (introns 1 and 3) and 52 (intron 2) bp in length. The comparison of the peptide sequence with A. niger rhg sequences revealed that the A1 rhg should be an endo-rhamnogalacturonases, more homologous to rhg A than rhg B A. niger known enzymes. The comparison of rhg nucleotide sequence from A. niger A1 with rhg A from A. niger shows several base changes. Most of these changes (59 %) are located at the third base of codons suggesting maintaining the same enzyme function. We used the rhamnogalacturonase A from Aspergillus aculeatus as a template to build a structural model of rhg A1 that adopted a right-handed parallel β-helix.
authors.affiliation: Laboratoire de Valorisation de la Biomasse et Production de Protéines chez les EucaryotesCentre de Biotechnologie de Sfax, University of Sfax, Route Sidi Mansour, BP 1177, 3018, Sfax, Tunisia.
authors.forename: Naourez
authors.initials: N
authors.lastname: Damak
authors.forename: Salma
authors.initials: S
authors.lastname: Abdeljalil
authors.forename: Noomen Hadj
authors.initials: NH
authors.lastname: Taeib
authors.forename: Ali
authors.initials: A
authors.lastname: Gargouri
mesh_terms: D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D005800:Genes, Fungal; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007438:Introns / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D017433:Protein Structure, Secondary; D016415:Sequence Alignment
chemical_list: D006026:Glycoside Hydrolases; C067959:rhamnogalacturonase A