The telomere-linked helicase (TLH) gene family in Magnaporthe oryzae: revised gene structure reveals a novel TLH-specific protein motif

Curr Genet. 2009 Jun;55(3):253-62. doi: 10.1007/s00294-009-0240-3. Epub 2009 Apr 10.

Abstract

Telomere-linked RecQ helicase (TLH) genes have been identified in several fungi, where they occur as small gene families with each member copy residing within ~10 kb of a telomere. Here we describe the characterization of all 11 TLH gene copies in the reference strain of the fungus Magnaporthe oryzae. A consensus gene prediction revealed that the previously reported TLH1 gene is actually a mutated copy, and the full-length gene is almost two times longer. Only four full-length TLH genes were present in the strain that was analyzed, with the remaining copies containing premature stops caused by point mutations, indels, transposon insertions, and a telomere truncation. Interestingly, all of the TLH gene copies possessed numerous mutations indicative of the action of the repeat-induced point mutation process. However, there was evidence of purifying selection indicating maintenance of gene function. Alignment of full-length proteins from M. oryzae, Schizosaccharomyces pombe and M. anisopliae revealed the presence of a novel, highly conserved protein motif which suggests that the telomere-linked helicases have different functions and/or substrates to the RecQ helicases encoded by "internal" genes.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Base Sequence
  • Chromosome Mapping
  • Chromosomes, Fungal / genetics
  • Conserved Sequence
  • DNA Transposable Elements / genetics
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • Gene Dosage
  • Magnaporthe / enzymology
  • Magnaporthe / genetics*
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Mutation
  • RecQ Helicases / genetics*
  • RecQ Helicases / metabolism
  • Selection, Genetic
  • Sequence Alignment / methods
  • Sequence Homology, Amino Acid
  • Sequence Homology, Nucleic Acid
  • Telomere / enzymology
  • Telomere / genetics*

Substances

  • DNA Transposable Elements
  • Fungal Proteins
  • RecQ Helicases