The Physcomitrium (Physcomitrella) patens PpKAI2L receptors for strigolactones and related compounds function via MAX2-dependent and independent pathways

Abstract In angiosperms, the α/β hydrolase DWARF14 (D14), along with the F-box protein MORE AXILLARY GROWTH2 (MAX2), perceives strigolactones (SL) to regulate developmental processes. The key SL biosynthetic enzyme CAROTENOID CLEAVAGE DIOXYGENASE8 (CCD8) is present in the moss Physcomitrium patens, and PpCCD8-derived compounds regulate moss extension. The PpMAX2 homolog is not involved in the SL response, but 13 PpKAI2LIKE (PpKAI2L) genes homologous to the D14 ancestral paralog KARRIKIN INSENSITIVE2 (KAI2) encode candidate SL receptors. In Arabidopsis thaliana, AtKAI2 perceives karrikins and the elusive endogenous KAI2-Ligand (KL). Here, germination assays of the parasitic plant Phelipanche ramosa suggested that PpCCD8-derived compounds are likely non-canonical SLs. (+)-GR24 SL analog is a good mimic for PpCCD8-derived compounds in P. patens, while the effects of its enantiomer (−)-GR24, a KL mimic in angiosperms, are minimal. Interaction and binding assays of seven PpKAI2L proteins pointed to the stereoselectivity towards (−)-GR24 for a single clade of PpKAI2L (eu-KAI2). Enzyme assays highlighted the peculiar behavior of PpKAI2L-H. Phenotypic characterization of Ppkai2l mutants showed that eu-KAI2 genes are not involved in the perception of PpCCD8-derived compounds but act in a PpMAX2-dependent pathway. By contrast, mutations in PpKAI2L-G, and -J genes abolished the response to the (+)-GR24 enantiomer, suggesting that PpKAI2L-G, and -J proteins are receptors for moss SLs.

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Genetic and Phenotypic Characterization of GII-4 Noroviruses That Circulated during 1987 to 2008

Journal of Virology ◽

10.1128/jvi.02614-09 ◽

2010 ◽

Vol 84 (18) ◽

pp. 9595-9607 ◽

Cited By ~ 52

Author(s):

Yang Yang ◽

Ming Xia ◽

Ming Tan ◽

Pengwei Huang ◽

Weiming Zhong ◽

...

Keyword(s):

Host Immunity ◽

Phenotypic Characterization ◽

Blood Group Antigens ◽

Binding Assays ◽

The Past ◽

Antigenic Properties ◽

Two Factors ◽

Genetic Clusters ◽

High Conservation

ABSTRACT The predominance and continual emergence of new variants in GII-4 noroviruses (NVs) in recent years have raised questions about the role of host immunity and histo-blood group antigens (HBGAs) in NV evolution. To address these questions, we performed a genetic and phenotypic characterization of GII-4 variants circulating in the past decade (1998 to 2008). Ninety-three GII-4 sequences were analyzed, and of them, 16 strains representing 6 genetic clusters were selected for further characterization. The HBGA binding properties were determined by both saliva- and oligosaccharide-binding assays using P particles as a model of NV capsid. The antigenic properties were also examined by enzyme immunoassay (EIA), Western blot analysis, and receptor blocking assay, using P-particle-specific antibodies from immunized mice and GII-4 virus-infected patients. Our results showed that 15 of the 16 GII-4 viruses bound to saliva of all A, B, and O secretors. Oligosaccharide binding assays yielded largely consistent results, although the binding affinities to some oligosaccharides varied among some strains. The only nonbinder had a mutation in the binding site. While antigenic variations were detected among the 16 strains, significant cross-blocking on the HBGA binding was also noted. Sequence alignment revealed high conservation of HBGA binding interfaces with some variations in adjacent regions. Taken together, our data suggested that the ability of GII-4 to recognize different secretor HBGAs persisted over the past decade, which may explain the predominance of GII-4 over other genotypes. Our data also indicated that both the host immunity and HBGAs play a role in NV evolution. While host immunity may continue driving NV for antigenic change, the functional selection by the HBGAs tends to lock the architecture of the capsid/HBGA interfaces and allows only limited variations outside the HBGA binding sites. A potential outcome of such counterselection between theses two factors in NV evolution is discussed.

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The Physcomitrium (Physcomitrella) patens PpKAI2L receptors for strigolactones and related compounds highlight MAX2 dependent and independent pathways

10.1101/2020.11.24.395954 ◽

2020 ◽

Author(s):

Mauricio Lopez-Obando ◽

Ambre Guillory ◽

François-Didier Boyer ◽

David Cornu ◽

Beate Hoffmann ◽

...

Keyword(s):

Physcomitrella Patens ◽

Hydrolytic Activity ◽

Parasitic Plant ◽

Flowering Plants ◽

Biosynthetic Enzyme ◽

Developmental Processes ◽

Phelipanche Ramosa ◽

F Box Protein ◽

Related Compounds ◽

H Protein

ABSTRACTIn flowering plants, the α/β hydrolase DWARF14 (D14) perceives strigolactone (SL) hormones and interacts with the F-box protein MORE AXILLARY GROWTH2 (MAX2) to regulate developmental processes. The key SL biosynthetic enzyme, CAROTENOID CLEAVAGE DEOXYGENASE8 (CCD8), is present in the moss Physcomitrium (Physcomitrella) patens, and PpCCD8-derived compounds regulate plant extension. However, perception of these still unknown compounds does not require the PpMAX2 homolog. Putative candidate receptors are among the 13 PpKAI2LIKE-A to -L genes, homologous to the ancestral D14 paralog KARRIKIN INSENSITIVE2 (KAI2). In Arabidopsis, AtKAI2 is the receptor for karrikins and a still elusive endogenous KAI2-Ligand (KL). Based on germination assays using seeds of the parasitic plant Phelipanche ramosa, we propose that PpCCD8-derived compounds are non-canonical SLs. We show that all tested PpKAI2L proteins can bind and cleave SL analogs, some with similar affinities to AtKAI2. The PpKAI2L-H protein shows a strong hydrolytic activity not found for other PpKAI2L. Moss mutants for all PpKAI2L gene subclades were obtained and tested for their response to SL analogs. We show that PpKAI2L-A to -E genes encode redundant proteins that are not involved in PpCCD8-derived compound perception, but rather act in a PpMAX2-dependant pathway. In contrast, mutations in PpKAI2L-G, and -J genes abolish the response to the SL analog (+)-GR24, suggesting that both these encoded proteins are receptors for PpCCD8-derived molecules.

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