CYSTEINE-RICH RECEPTOR-LIKE PROTEIN KINASES: their evolution, structure, and roles in stress response and development

Abstract

Plant-specific receptor-like protein kinases (RLKs) are central components for sensing the extracellular microenvironment. CYSTEINE-RICH RLKs (CRKs) are one of the biggest subgroups of RLKs. Their physiological and molecular roles have only begun to be elucidated, but recent studies highlight the diverse types of proteins interacting with CRKs, as well as the localization of CRKs and their lateral organization within the plasma membrane. Originally proposed to act as redox sensors, the potential ligands perceived by the DOMAIN OF UNKNOWN FUNCTION 26 (DUF26)-containing extracellular region of the CRKs remain elusive. Here, we summarize the recent progress in the analysis of CRK evolution, molecular function and their roles in plant development, abiotic stress responses, plant immunity and symbiosis. The currently available information on CRKs and related proteins suggests the CRKs to be central regulators of plant signaling pathways. However, more research using classical methods and interdisciplinary approaches in various plant model species, as well as structural analyses, will not only enhance our understanding of the molecular function of CRKs, but also elucidate the contribution of other cellular components in CRK-mediated signaling pathways.

A haplotype-resolved chromosome-level assembly and annotation of European hazelnut (C. avellana cv. Jefferson) provides insight into mechanisms of eastern filbert blight resistance

“…In recent years it has become apparent that cysteine-rich receptor-like secreted proteins (CRRSPs) have crucial involvement in plant-fungal pathogen interactions ( Zeiner i 2023 ). Gnk2 from ginkgo ( Ginkgo biloba ) and two maize ( Zea mays ) proteins, AFP1 and AFP2 , bind to mannose during the defense response against fungal pathogens ( Miyakawa et al 2014 ; Ma et al 2018 ).…”

A haplotype-resolved chromosome-level assembly and annotation of European hazelnut (C. avellanacv. Jefferson) provides insight into mechanisms of eastern filbert blight resistance

“…In recent years it has become apparent that cysteine-rich receptor-like secreted proteins (CRRSPs) have crucial involvement in plant-fungal pathogen interactions (Zeiner et al, 2023). Gnk2 from ginkgo ( Ginkgo biloba ) and two maize ( Zea mays ) proteins, AFP1 and AFP2 , bind to mannose during the defense response against fungal pathogens (Miyakawa et al, 2014; Ma et al, 2018).…”

An update on evolutionary, structural, and functional studies of receptor-like kinases in plants

“…With 44 members in Arabidopsis , DUF26 (CRK) is another cysteine-rich repeat domain kinase receptor that shares similarities with lectins but is different than the S-locus glycoprotein and contains C-X8-C-X2-C motifs ( Zeiner et al., 2023 ). These RLKs containing cysteine-rich repeats were termed cysteine-rich domain-containing receptor-like kinases (CRR RLKs), which play a role in defense and stress responses ( Chen, 2001 ; Vaattovaara et al., 2019 ).…”