Rapid evolution in plant chitinases: molecular targets of selection in plant-pathogen coevolution

J G Bishop; A M Dean; T Mitchell-Olds

doi:10.1073/pnas.97.10.5322

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Rapid evolution in plant chitinases: molecular targets of selection in plant-pathogen coevolution

Journal article

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Rapid evolution in plant chitinases: molecular targets of selection in plant-pathogen coevolution

J G Bishop, A M Dean and T Mitchell-Olds

Proceedings of the National Academy of Sciences - PNAS, Vol.97(10), pp.5322-5327

05/09/2000

DOI: https://doi.org/10.1073/pnas.97.10.5322

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https://hdl.handle.net/2376/110578

PMCID: PMC25827

PMID: 10805791

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Abstract

Amino Acid Sequence

Arabidopsis - enzymology

Models, Molecular

Molecular Sequence Data

Phylogeny

Chitinases - genetics

Arabidopsis - genetics

Brassicaceae - genetics

Brassica - genetics

Conserved Sequence

Protein Conformation

Plant Diseases

Brassica - enzymology

Chitinases - chemistry

Brassicaceae - enzymology

Evolution, Molecular

Many pathogen recognition genes, such as plant R-genes, undergo rapid adaptive evolution, providing evidence that these genes play a critical role in plant-pathogen coevolution. Surprisingly, whether rapid adaptive evolution also occurs in genes encoding other kinds of plant defense proteins is unknown. Unlike recognition proteins, plant chitinases attack pathogens directly, conferring disease resistance by degrading chitin, a component of fungal cell walls. Here, we show that nonsynonymous substitution rates in plant class I chitinase often exceed synonymous rates in the plant genus Arabis (Cruciferae) and in other dicots, indicating a succession of adaptively driven amino acid replacements. We identify individual residues that are likely subject to positive selection by using codon substitution models and determine the location of these residues on the three-dimensional structure of class I chitinase. In contrast to primate lysozymes and plant class III chitinases, structural and functional relatives of class I chitinase, the adaptive replacements of class I chitinase occur disproportionately in the active site cleft. This highly unusual pattern of replacements suggests that fungi directly defend against chitinolytic activity through enzymatic inhibition or other forms of chemical resistance and identifies target residues for manipulating chitinolytic activity. These data also provide empirical evidence that plant defense proteins not involved in pathogen recognition also evolve in a manner consistent with rapid coevolutionary interactions.

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Title: Rapid evolution in plant chitinases: molecular targets of selection in plant-pathogen coevolution
Creators: J G Bishop - Max Planck Institute for Chemical Ecology, Carl-Zeiss-promenade 10, Jena, Germany. bishop@vancouver.wsu.edu
A M Dean
T Mitchell-Olds
Publication Details: Proceedings of the National Academy of Sciences - PNAS, Vol.97(10), pp.5322-5327
Academic Unit: Biological Sciences, School of
Publisher: United States
Identifiers: 99900547445101842
Language: English
Resource Type: Journal article