Genomic DNA analysis of genes encoding (hemi-)cellulolytic enzymes of the anaerobic fungus Piromyces sp. E2.
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.
Harhangi
Harry R
HR
Department of Microbiology, Faculty of Science, University of Nijmegen, Toernooiveld 1, NL-6525 ED, Nijmegen, The Netherlands.
Akhmanova
Anna
A
Steenbakkers
Peter J M
PJ
Jetten
Mike S M
MS
van der Drift
Chris
C
Op den Camp
Huub J M
HJ
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
D004271:DNA, Fungal; D005656:Fungal Proteins; D002480:Cellulase