Dataset Information

Ice-binding site of snow mold fungus antifreeze protein deviates from structural regularity and high conservation.

ABSTRACT: Antifreeze proteins (AFPs) are found in organisms ranging from fish to bacteria, where they serve different functions to facilitate survival of their host. AFPs that protect freeze-intolerant fish and insects from internal ice growth bind to ice using a regular array of well-conserved residues/motifs. Less is known about the role of AFPs in freeze-tolerant species, which might be to beneficially alter the structure of ice in or around the host. Here we report the 0.95-Å high-resolution crystal structure of a 223-residue secreted AFP from the snow mold fungus Typhula ishikariensis. Its main structural element is an irregular ?-helix with six loops of 18 or more residues that lies alongside an ?-helix. ?-Helices have independently evolved as AFPs on several occasions and seem ideally structured to bind to several planes of ice, including the basal plane. A novelty of the ?-helical fold is the nonsequential arrangement of loops that places the N- and C termini inside the solenoid of ?-helical coils. The ice-binding site (IBS), which could not be predicted from sequence or structure, was located by site-directed mutagenesis to the flattest surface of the protein. It is remarkable for its lack of regularity and its poor conservation in homologs from psychrophilic diatoms and bacteria and other fungi.

SUBMITTER: Kondo H

PROVIDER: S-EPMC3386094 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Ice-binding site of snow mold fungus antifreeze protein deviates from structural regularity and high conservation.

Kondo Hidemasa H Hanada Yuichi Y Sugimoto Hiroshi H Hoshino Tamotsu T Garnham Christopher P CP Davies Peter L PL Tsuda Sakae S

Proceedings of the National Academy of Sciences of the United States of America 20120529 24

Antifreeze proteins (AFPs) are found in organisms ranging from fish to bacteria, where they serve different functions to facilitate survival of their host. AFPs that protect freeze-intolerant fish and insects from internal ice growth bind to ice using a regular array of well-conserved residues/motifs. Less is known about the role of AFPs in freeze-tolerant species, which might be to beneficially alter the structure of ice in or around the host. Here we report the 0.95-Å high-resolution crystal s ...[more]

PMID: 22645341

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Project description:Pink snow mold, caused by a phytopathogenic and psychrotolerant fungus, Microdochium nivale, is a severe disease of winter cereals and grasses that predominantly occurs under snow cover or shortly after its melt. Snow mold has significantly progressed during the past decade, often reaching epiphytotic levels in northern countries and resulting in dramatic yield losses. In addition, M. nivale gradually adapts to a warmer climate, spreading to less snowy territories and causing different types of plant diseases throughout the growing period. Despite its great economic importance, M. nivale is poorly investigated; its genome has not been sequenced and its crucial virulence determinants have not been identified or even predicted. In our study, we applied a hybrid assembly based on Oxford Nanopore and Illumina reads to obtain the first genome sequence of M. nivale. 11,973 genes (including 11,789 protein-encoding genes) have been revealed in the genome assembly. To better understand the genetic potential of M. nivale and to obtain a convenient reference for transcriptomic studies on this species, the identified genes were annotated and split into hierarchical three-level functional categories. A file with functionally classified M. nivale genes is presented in our study for general use. M. nivale gene products that best meet the criteria for virulence factors have been identified. The genetic potential to synthesize human-dangerous mycotoxins (fumonisin, ochratoxin B, aflatoxin, and gliotoxin) has been revealed for M. nivale. The transcriptome analysis combined with the assays for extracellular enzymatic activities (conventional virulence factors of many phytopathogens) was carried out to assess the effect of host plant (rye) metabolites on the M. nivale phenotype. In addition to disclosing plant-metabolite-upregulated M. nivale functional gene groups (including those related to host plant protein destruction and amino acid metabolism, xenobiotic detoxication (including phytoalexins benzoxazinoids), cellulose destruction (cellulose monooxygenases), iron transport, etc.), the performed analysis pointed to a crucial role of host plant lipid destruction and fungal lipid metabolism modulation in plant-M. nivale interactions.

Dataset Information

Ice-binding site of snow mold fungus antifreeze protein deviates from structural regularity and high conservation.

Publications

Ice-binding site of snow mold fungus antifreeze protein deviates from structural regularity and high conservation.

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