Phylogenetic analysis, genomic organization, and expression analysis of multi-copper oxidases in the ectomycorrhizal basidiomycete Laccaria bicolor.

• In forest soils, ectomycorrhizal and saprotrophic Agaricales differ in their strategies for carbon acquisition, but share common gene families encoding multi-copper oxidases (MCOs). These enzymes are involved in the oxidation of a variety of soil organic compounds. • The MCO gene family of the ectomycorrhizal fungus Laccaria bicolor is composed of 11 genes divided into two distinct subfamilies corresponding to laccases ( lcc) sensu stricto ( lcc1 to lcc9), sharing a high sequence homology with the coprophilic Coprinopsis cinerea laccase genes, and to ferroxidases ( lcc10 and lcc11) that are not present in C. cinerea. The fet3-like ferroxidase genes lcc10 and lcc11 in L. bicolor are each arranged in a mirrored tandem orientation with an ftr gene coding for an iron permease. Unlike C. cinerea, L. bicolor has no sid1/ sidA gene for siderophore biosynthesis. • Transcript profiling using whole-genome expression arrays and quantitative reverse transcriptase–polymerase chain reaction (qRT-PCR) revealed that some transcripts were very abundant in ectomycorrhizas ( lcc3 and lcc8), in fruiting bodies ( lcc7) or in the free-living mycelium grown on agar medium ( lcc9 and lcc10), suggesting a specific function of these MCOs. • The amino acid composition of the MCO substrate binding sites suggests that L. bicolor MCOs interact with substrates different from those of saprotrophic fungi. [ABSTRACT FROM AUTHOR]