Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain
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 (eS...
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th-mahidol.251532018-08-24T09:18:18Z Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain Sushma Naithani Thanat Chookajorn Daniel R. Ripoll June B. Nasrallah Cornell University Mahidol University Multidisciplinary 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. 2018-08-24T02:18:18Z 2018-08-24T02:18:18Z 2007-07-17 Article Proceedings of the National Academy of Sciences of the United States of America. Vol.104, No.29 (2007), 12211-12216 10.1073/pnas.0705186104 00278424 2-s2.0-34547503841 https://repository.li.mahidol.ac.th/handle/123456789/25153 Mahidol University SCOPUS https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=34547503841&origin=inward |
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Multidisciplinary Sushma Naithani Thanat Chookajorn Daniel R. Ripoll June B. Nasrallah Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain |
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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. |
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Cornell University |
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Cornell University Sushma Naithani Thanat Chookajorn Daniel R. Ripoll June B. Nasrallah |
format |
Article |
author |
Sushma Naithani Thanat Chookajorn Daniel R. Ripoll June B. Nasrallah |
author_sort |
Sushma Naithani |
title |
Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain |
title_short |
Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain |
title_full |
Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain |
title_fullStr |
Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain |
title_full_unstemmed |
Structural modules for receptor dimerization in the S-locus receptor kinase extracellular domain |
title_sort |
structural modules for receptor dimerization in the s-locus receptor kinase extracellular domain |
publishDate |
2018 |
url |
https://repository.li.mahidol.ac.th/handle/123456789/25153 |
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1763495668045840384 |