Variability of chromosome structure in pathogenic fungi--of 'ends and odds'.
Chromatin structure can affect the organization and maintenance of chromosomes. Recent discoveries in several filamentous fungi suggest mechanisms for the clustering and co-regulation of secondary metabolite genes or pathogenicity islands. An extreme case of this may be fungal 'accessory', 'conditionally dispensable', or 'supernumerary' chromosomes that often confer beneficial traits. Fungal supernumerary chromosomes may be derived by similar mechanisms as animal or plant B chromosomes, and we thus propose that this term should be reconsidered to capture the wide variety of fungal accessory chromosomes. In some fungi, both the 'ends' of chromosomes and these 'odd B chromosomes are enriched with a silencing histone modification, H3 lysine 27 trimethylation (H3K27me3), suggesting parallel mechanisms in evolving subtelomeric or B-chromosomal pathogenicity islands and secondary metabolite clusters (SMCs).
Department of Biochemistry and Biophysics, Center of Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, United States.
Jonathan M
JM
Galazka
Department of Biochemistry and Biophysics, Center of Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, United States. Electronic address: freitagm@cgrb.oregonstate.edu.
Michael
M
Freitag
D002843:Chromatin / Q000378:metabolism; D022004:Chromosome Structures; D015825:Chromosomes, Fungal; D005658:Fungi / Q000166:cytology* / Q000378:metabolism / Q000502:physiology*; D006657:Histones / Q000378:metabolism
D002843:Chromatin; D006657:Histones