Atypical and nucellin-like aspartic proteases: emerging players in plant developmental processes and stress responses

Atypical and nucellin-like aspartic proteases display unique enzymatic features and are implicated in wide-ranging developmental and stress responses, suggesting tight activity regulation, functional specialization, and the specific conversion of unique substrates. Abstract Members of the pepsin-lik...

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Published in:Journal of experimental botany 2019-04, Vol.70 (7), p.2059-2076
Main Authors: Soares, André, Ribeiro Carlton, Sofia M, Simões, Isaura
Format: Article
Language:English
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Summary:Atypical and nucellin-like aspartic proteases display unique enzymatic features and are implicated in wide-ranging developmental and stress responses, suggesting tight activity regulation, functional specialization, and the specific conversion of unique substrates. Abstract Members of the pepsin-like family (A1) of aspartic proteases (APs) are widely distributed in plants. A large number of genes encoding putative A1 APs are found in different plant genomes, the vast majority of which exhibit distinct features when compared with the so-called typical APs (and, therefore, grouped as atypical and nucellin-like APs). These features include the absence of the plant-specific insert; an unusually high number of cysteine residues; the nature of the amino acids preceding the first catalytic aspartate; and unexpected localizations. The over-representation of atypical and nucellin-like APs in plants is suggestive of greater diversification of protein functions and a more regulatory role for these APs, as compared with the housekeeping function generally attributed to typical APs. New functions have been uncovered for non-typical APs, with proposed roles in biotic and abiotic stress responses, chloroplast metabolism, and reproductive development, clearly suggesting functional specialization and tight regulation of activity. Furthermore, unusual enzymatic properties have also been documented for some of these proteases. Here, we give an overview of the current knowledge on the distinctive features and functions of both atypical and nucellin-like APs, and discuss this emerging pattern of functional complexity and specialization among plant pepsin-like proteases.
ISSN:0022-0957
1460-2431
DOI:10.1093/jxb/erz034