Physiology and molecular biology of the lignin peroxidases of Phanerochaete chrysosporium

Abstract

The white-rot basidiomycete Phanerochaete chrysosporium produces lignin peroxidases (LiPs), a family of extracellular glycosylated heme proteins, as major components of its lignin-degrading system. Up to 15 LiP isozymes, ranging in M(r) values from 38,000 to 43,000, are produced depending on culture conditions and strains employed. Manganese-dependent peroxidases (MnPs) are a second family of extracellular heme proteins produced by P. chrysosporium that are also believed to be important in lignin degradation by this organism. LiP and MnP production is seen during secondary metabolism and is completely suppressed under conditions of excess nitrogen and carbon. Excess Mn(II) in the medium, on the other hand, suppresses LiP production but enhances MnP production. Nitrogen regulation of LiP and MnP production is independent of carbon and Mn(II) regulation. LiP activity is also affected by idiophasic extracellular proteases. Intracellular cAMP levels appear to be important in regulating the production of LiPs and MnPs, although LiP production is affected more than MnP production. Studies on the sequencing and characterization of lip cDNAs and genes of P. chrysosporium have shown that the major LiP isozymes are each encoded by a separate gene. Each lip gene encodes a mature protein that is 343-344 amino acids long, contains 1 putative N-glycosylation site, a number of putative O-glycosylation sites, and is preceded by a 27-28-amino acid leader peptide ending in a Lys-Arg cleavage site. The coding region of each lip gene is interrupted by 8-9 introns (50-63 bp), and the positions of the last two introns appear to be highly conserved. There are substantial differences in the temporal transcription patterns of the major lip genes. The sequence data suggest the presence of three lip gene subfamilies. The genomic DNA of P. chrysosporium strain BKMF-1767 was resolved into 10 chromosomes (genome size of 29 Mb), and that of strain ME-446 into 11 chromosomes (genome size of 32 Mb). The lip genes have been localized to five chromosomes in BKMF-1767 and to four chromosomes in ME-446. DNA transformation studies have reported both integrative and non-integrative transformation in P. chrysosporium.

Elevation of Intracellular cAMP Levels by Dominant Active Heterotrimeric G Protein Alpha SubunitsScGP-AandScGP-Cin Homobasidiomycete,Schizophyllum commune

“…The 3 0 region of primer R6 was constructed so as to overhang the intron in order to prevent the contaminated genomic DNA from amplifying. The 20 (15) clones that harbored pSc3-RAS (Q61L) (RAS wild type) in their genomes transcribed genes (data not shown). To confirm that the transformed RAS (Q61L) gene and RAS wild type gene (containing introns) were processed correctly, each RT-PCR product was sequenced.…”

“…Fax: +81-24-593-2155; E-mail: yamagisi@affrc.go.jp Abbreviations: RAS, Schizophyllum RAS gene; ScGP-A, Schizophyllum commune G protein alpha subunit A; ScGP-C, Schizophyllum commune G protein alpha subunit C and bioremediation. [13][14][15] Although the mechanism regulating the cAMP level in homobasidiomycete has not yet been explained, the putative components that are supposed to activate adenylyl cyclase have been reported. The homobasidiomycete RAS gene was first identified from Lentinus edodes (LeRas), which could functionally replace its homolog genes (ScRAS1 and ScRAS2) in S. cerevisiae.…”

Extracellular Ligninolytic Enzymes in Bjerkandera adusta and Lentinus squarrosulus

“…From an ecophysiological point of view, mushrooms can be broadly classified into wood-decaying, mycorrhiza-forming, and litter-decomposing fungi. The most important and potent wooddestroying organisms are white-and brown-rot fungi, which attack various components of the wood cell wall [5]. Whiterot fungi (WRF) play an essential role in the decomposition of dead trees, especially in the degradation of lignin.…”

Heterologous expression of the msp2 gene from Marasmius scorodonius

“…These enzymes were purified to apparent homogeneity, sequenced using ESI-MS/MS and MALDI-TOF-MS, and their cDNAs were cloned (Scheibner et al 2008). Homology searches displayed sequence similarities of both MsP1 Such low expression levels of peroxidases are typical of fungal species in their natural environment (Conesa et al 2002;Reddy and D'Souza 1994). This impedes their extraction, characterization, and technical application.…”