title: New fungal defensin-like peptides provide evidence for fold change of proteins in evolution.
abstract: Defensins containing a consensus cystine framework, Cys[1]…Cys[2]X3Cys[3]…Cys[4]… Cys[5]X1Cys[6](X, any amino acid except Cys; …, variable residue numbers), are extensively distributed in a variety of multicellular organisms (plants, fungi and invertebrates) and essentially involved in immunity as microbicidal agents. This framework is a prerequisite for forming the cysteine-stabilized α-helix and β-sheet (CSαβ) fold, in which the two invariant motifs, Cys[2]X3Cys[3]/Cys[5]X1Cys[6], are key determinants of fold formation. By using a computational genomics approach, we identified a large superfamily of fungal defensin-like peptides (fDLPs) in the phytopathogenic fungal genus - Zymoseptoria, which includes 132 structurally typical and 63 atypical members. These atypical fDLPs exhibit an altered cystine framework and accompanying fold change associated with their secondary structure elements and disulfide bridge patterns, as identified by protein structure modelling. Despite this, they definitely are homologous with the typical fDLPs in view of their precise gene structure conservation and identical precursor organization. Sequence and structural analyses combined with functional data suggest that most of Zymoseptoria fDLPs might have lost their antimicrobial activity. The present study provides a clear example of fold change in the evolution of proteins and is valuable in establishing remote homology among peptide superfamily members with different folds.
authors.affiliation: Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China.
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Gao
authors.affiliation: Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China Zhusy@ioz.ac.cn.
authors.forename: Shunyi
authors.initials: S
authors.lastname: Zhu
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000737:chemistry* / Q000235:genetics; D003545:Cysteine / Q000737:chemistry / Q000235:genetics; D023082:Defensins / Q000737:chemistry* / Q000235:genetics; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D005800:Genes, Fungal; D008958:Models, Molecular; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D017510:Protein Folding; D016415:Sequence Alignment
chemical_list: D023082:Defensins; D005656:Fungal Proteins; D003545:Cysteine
keywords: Gene discovery; cysteine-stabilized α-helical and β-sheet fold; exon-intron organization; phytopathogenic fungus; structural evolution