title: Genomic DNA analysis of genes encoding (hemi-)cellulolytic enzymes of the anaerobic fungus Piromyces sp. E2.
abstract: Anaerobic fungi contain more than one copy of genes encoding (hemi-)cellulases in their genome. The arrangement of these genes on the chromosomes was not known. A genomic DNA (gDNA) library of Piromyces sp. E2 was screened with different probes specific for (hemi-)cellulolytic enzymes. This screening resulted in three gDNA clones with genes encoding glycoside hydrolase enzymes of families 1 (beta-glucosidase), 6 (exoglucanase) and 26 (mannanase). Each clone contained two or more genes of the same family. Comparison of the gene copies on a clone revealed that they were highly homologous, and in addition, 54-75% of the substitutions was synonymous. One of the mannanase genes contained an intron. PCR with selected primers resulted in a gDNA clone with a new representative (cel9B) of glycoside hydrolase family 9 (endoglucanase). Comparison with cel9A revealed that cel9B had 67% homology on the nucleotide level. Furthermore, three introns were present. All results of this paper taken together provided evidence for duplications of (hemi-)cellulolytic genes, which resulted in clusters of almost identical genes arranged head-to-tail on the genome. In contrast to other eukaryotes, this phenomenon appears frequently in anaerobic fungi.
authors.affiliation: Department of Microbiology, Faculty of Science, University of Nijmegen, Toernooiveld 1, NL-6525 ED, Nijmegen, The Netherlands.
authors.forename: Harry R
authors.initials: HR
authors.lastname: Harhangi
authors.forename: Anna
authors.initials: A
authors.lastname: Akhmanova
authors.forename: Peter J M
authors.initials: PJ
authors.lastname: Steenbakkers
authors.forename: Mike S M
authors.initials: MS
authors.lastname: Jetten
authors.forename: Chris
authors.initials: C
authors.lastname: van der Drift
authors.forename: Huub J M
authors.initials: HJ
authors.lastname: Op den Camp
mesh_terms: D024509:3' Flanking Region / Q000235:genetics; D015139:Blotting, Southern; D002480:Cellulase / Q000235:genetics*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D005656:Fungal Proteins / Q000235:genetics; D018628:Gene Dosage; D008969:Molecular Sequence Data; D020089:Piromyces / Q000201:enzymology / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D002480:Cellulase