RESUMEN
Immune responses are triggered when pattern recognition receptors recognize microbial molecular patterns. The Arabidopsis (Arabidopsis thaliana) receptor-like cytoplasmic kinase BOTRYTIS-INDUCED KINASE1 (BIK1) acts as a signaling hub of plant immunity. BIK1 homeostasis is maintained by a regulatory module in which CALCIUM-DEPENDENT PROTEIN KINASE28 (CPK28) regulates BIK1 turnover via the activities of two E3 ligases. Immune-induced alternative splicing of CPK28 attenuates CPK28 function. However, it remained unknown whether CPK28 is under proteasomal control. Here, we demonstrate that CPK28 undergoes ubiquitination and 26S proteasome-mediated degradation, which is enhanced by flagellin treatment. Two closely related ubiquitin ligases, ARABIDOPSIS TÓXICOS EN LEVADURA31 (ATL31) and ATL6, specifically interact with CPK28 at the plasma membrane; this association is enhanced by flagellin elicitation. ATL31/6 directly ubiquitinate CPK28, resulting in its proteasomal degradation. Furthermore, ATL31/6 promotes the stability of BIK1 by mediating CPK28 degradation. Consequently, ATL31/6 positively regulate BIK1-mediated immunity. Our findings reveal another mechanism for attenuating CPK28 function to maintain BIK1 homeostasis and enhance immune responses.
Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Inmunidad de la Planta/genética , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteínas Quinasas/genética , Ubiquitina-Proteína Ligasas/genética , Arabidopsis/inmunología , Proteínas de Arabidopsis/metabolismo , Proteínas Quinasas/metabolismo , Transducción de Señal , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
E3 ubiquitin ligases play critical roles in regulating plant response to salt stress. Arabidopsis Tóxicos En Levadura (ATL) is a subfamily of RING-type E3 ubiquitin ligases widely conserved in plant species. ATL genes have been shown to be involved in regulating plant response to biotic or abiotic stresses. We previously found that a pair of ATL genes, ATL31 and ATL6 positively regulated plant innate immunity. However, whether ATL31/6 are also involved in salt stress response remains to be investigated. Here, we demonstrate that ATL31/6 are induced by salt stress. The atl31 atl6 double mutant exhibits increased salt tolerance compared to the wild-type plants, while transgenic plants overexpressing ATL31 are more salt-sensitive. Notably, ATL31 and ATL6 do not participate in the abscisic acid (ABA) response. Furthermore, NaCl treatment induces the proteasomal degradation of ATL31 proteins. Together, we demonstrate that ATL31/6 positively regulate plant tolerance to salt stress, which is independent of ABA, and our work reveals that ATL31/6 are involved in regulating plant response to both biotic and abiotic stress.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Ácido Abscísico/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulación de la Expresión Génica de las Plantas , Plantas Modificadas Genéticamente/metabolismo , Estrés Salino/genética , Estrés Fisiológico , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Pathogen-associated molecular patterns (PAMPs) trigger plant innate immunity that acts as the first line of inducible defense against pathogen infection. A receptor-like cytoplasmic kinase BOTRYTIS-INDUCED KINASE 1 (BIK1) functions as a signaling hub immediately downstream of multiple pattern recognition receptors (PRRs). It is known that PLANT U-BOX PROTEIN 25 (PUB25) and PUB26 ubiquitinate BIK1 and mediate BIK1 degradation. However, how BIK1 homeostasis is maintained is not fully understood. Here, we show that two closely related ubiquitin ligases, RING DOMAIN LIGASE 1 (RGLG1) and RGLG2, preferentially associate with the hypo-phosphorylated BIK1 and promote the association of BIK1 with the co-receptor for several PRRs, BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). PUB25 interacts with RGLG2 and mediates its degradation. In turn, RGLG2 represses the ubiquitin ligase activity of PUB25. RGLG1/2 suppress PUB25-mediated BIK1 degradation, promote BIK1 protein accumulation, and positively regulate immune signaling in a ubiquitin ligase activity-dependent manner. Our work reveals how BIK1 homeostasis is maintained by the interplay of different ubiquitin ligases.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Botrytis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fosforilación , Arabidopsis/metabolismo , Ligasas/metabolismo , Ubiquitina/metabolismo , Proteostasis , Proteínas Quinasas/genética , Proteínas Quinasas/metabolismo , Proteínas de Plantas/metabolismo , Receptores de Reconocimiento de Patrones/metabolismo , Homeostasis , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Inmunidad de la Planta/fisiologíaRESUMEN
A near-infrared light-controlled hybrid platform with polypeptide-engineered functionalized gold nanorods has been designed for reversible presentation of the immobilized ligands to cell surface receptors on the engineered materials.
Asunto(s)
Oro/química , Rayos Infrarrojos , Nanotubos/química , Péptidos/química , Ingeniería de Proteínas , Animales , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Oro/farmacología , Ligandos , Ratones , Células 3T3 NIH , Péptidos/farmacología , Relación Estructura-ActividadRESUMEN
A novel approach to build porous cell-laden hydrogels through the self-assembly of coiled-coil polypeptides on the surface of physical microgels was developed. Both the extracellular microenvironments of pores and physical microgels within assembled constructs could be tailored simultaneously by tuning the polypeptide and morphological features of microgels.
Asunto(s)
Hidrogeles , Péptidos/químicaRESUMEN
Photo-cross-linkable physical hydrogels based on the coiled-coil region of the cartilage oligomeric matrix protein and polyethylene glycol diacrylate were designed and synthesized to mimic the natural extracellular matrix for three-dimensional cell culture. The engineered polypeptides (Pcys and RGDPcys) were modified with polyethylene glycol diacrylate to form photo-cross-linkable multifunctional macromers via the Michael-type addition reaction between the cysteine residues and acrylates. Gel formation was confirmed by rheological measurements. The swelling ratio and stability of 10% w/v RGDP-PEG-acrylate6k hydrogel were 38% and 15 days, respectively. Spreading and migration of encapsulated fibroblast cells were observed in these physical hydrogels, while round cells were observed in a covalent control hydrogel. In addition, rapid self-healing of these physical hydrogels can provide a flexible way to build tissue by self-assembly and bottom-up approach. The results demonstrate that such physical hydrogels are expected to have great potential applications in tissue engineering.