Publication: Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain
Issued Date
2007-07-17
Resource Type
ISSN
00278424
Other identifier(s)
2-s2.0-34547503841
Rights
Mahidol University
Rights Holder(s)
SCOPUS
Bibliographic Citation
Proceedings of the National Academy of Sciences of the United States of America. Vol.104, No.29 (2007), 12211-12216
Suggested Citation
Sushma Naithani, Thanat Chookajorn, Daniel R. Ripoll, June B. Nasrallah Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain. Proceedings of the National Academy of Sciences of the United States of America. Vol.104, No.29 (2007), 12211-12216. doi:10.1073/pnas.0705186104 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/25153
Research Projects
Organizational Units
Authors
Journal Issue
Thesis
Title
Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain
Other Contributor(s)
Abstract
The highly polymorphic S-locus receptor kinase (SRK) is the stigma determinant of specificity in the self-incompatibility response of the Brassicaceae. SRK spans the plasma membrane of stigma epidermal cells, and it is activated in an allele-specific manner on binding of its extracellular region (eSRK) to its cognate pollen coat-localized S-locus cysteine-rich (SCR) ligand. SRK, like several other receptor kinases, forms dimers in the absence of ligand. To identify domains in SRK that mediate ligand-independent dimerization, we assayed eSRK for self-interaction in yeast. We show that SRK dimerization is mediated by two regions in eSRK, primarily by a C-terminal region inferred by homology modeling/fold recognition techniques to assume a PAN_APPLE-like structure, and secondarily by a region containing a signature sequence of the S-domain gene family, which might assume an EGF-like structure. We also show that eSRK exhibits a marked preference for homodimerization over heterodimerization with other eSRK variants and that this preference is mediated by a small, highly variable region within the PAN_APPLE domain. Thus, the extensive polymorphism exhibited by the eSRK not only determines differential affinity toward the SCR ligand, as has been assumed thus far, but also underlies a previously unrecognized allelic specificity in SRK dimerization. We propose that preference for SRK homodimerization explains the codominance exhibited by a majority of SRKs in the typically heterozygous stigmas of self-incompatible plants, whereas an increased propensity for heterodimerization combined with reduced affinity of heterodimers for cognate SCRs might underlie the dominant-recessive or mutual weakening relationships exhibited by some SRK allelic pairs. © 2007 by The National Academy of Sciences of the USA.