Multifarious Roles of Intrinsic Disorder in Proteins Illustrate Its Broad Impact on Plant Biology
Intrinsically disordered proteins (IDPs) are highly abundant in eukaryotic proteomes. Plant IDPs play critical roles in plant biology and often act as integrators of signals from multiple plant regulatory and environmental inputs. Binding promiscuity and plasticity allow IDPs to interact with multiple partners in protein interaction networks and provide important functional advantages in molecular recognition through transient protein–protein interactions. Short interaction-prone segments within IDPs, termed molecular recognition features, represent potential binding sites that can undergo disorder-to-order transition upon binding to their partners. In this review, we summarize the evidence for the importance of IDPs in plant biology and evaluate the functions associated with intrinsic disorder in five different types of plant protein families experimentally confirmed as IDPs. Functional studies of these proteins illustrate the broad impact of disorder on many areas of plant biology, including abiotic stress, transcriptional regulation, light perception, and development. Based on the roles of disorder in the protein–protein interactions, we propose various modes of action for plant IDPs that may provide insight for future experimental approaches aimed at understanding the molecular basis of protein function within important plant pathways.

title: N-terminal domains of DELLA proteins are intrinsically unstructured in the absence of interaction with GID1/gibberellic acid receptors.
abstract: The plant growth-repressing DELLA proteins (DELLAs) are known to represent a convergence point in integration of multiple developmental and environmental signals in planta, one of which is hormone gibberellic acid (GA). Binding of the liganded GA receptor (GID1/GA) to the N-terminal domain of DELLAs is required for GA-induced degradation of DELLAs via the ubiquitin-proteasome pathway, thus derepressing plant growth. However, the conformational changes of DELLAs upon binding to GID1/GA, which are the key to understanding the precise mechanism of GID1/GA-mediated degradation of DELLAs, remain unclear. Using biophysical, biochemical, and bioinformatics approaches, we demonstrated for the first time that the unbound N-terminal domains of DELLAs are intrinsically unstructured proteins under physiological conditions. Within the intrinsically disordered N-terminal domain of DELLAs, we have identified several molecular recognition features, sequences known to undergo disorder-to-order transitions upon binding to interacting proteins in intrinsically unstructured proteins. In accordance with the molecular recognition feature analyses, we have observed the binding-induced folding of N-terminal domains of DELLAs upon interaction with AtGID1/GA. Our results also indicate that DELLA proteins can be divided into two subgroups in terms of their molecular compactness and their interactions with monoclonal antibodies.

title: Effect of burn injury on glucocorticoid receptor binding activity in rat muscle.
abstract: Burn injury is associated with increased muscle proteolysis and up-regulated gene expression in the proteolytic pathway. Glucocorticoids (GCs) are the most important mediator of burn injury induced muscle cachexia. However, the understanding of the mechanisms of GCs action in response to burn injury remains elusive. It is well known that GC acts by binding its own receptor. Therefore, in the present study, we examined the influence of burn injury on the hormone binding activity of the glucocorticoid receptor (GR) in skeletal muscle. Burn injury resulted in increased hormone binding activity in extensor digitorum longus (EDL) and soleus muscles. Scatchard plots revealed that the increased GR hormone binding activity reflected increased numbers of hormone binding sites, whereas receptor affinity for GCs was unchanged. Western blot analysis showed that dissociation of GR/heat shock protein 90 heterocomplex or increase in GR protein may account for the effect of burn injury. The GR antagonist RU 38486 blocked the burn injury-induced increase in GR hormone binding activity, implicating a positive regulatory effect of GCs on GR binding activity under the present experimental conditions.

title: Kruppel-like factor 5 (KLF5) is critical for conferring uterine receptivity to implantation
abstract: A blastocyst will implant only when the uterus becomes receptive. Following attachment, luminal epithelial cells undergo degeneration at the site of the blastocyst. Although many genes critical for uterine receptivity are primarily regulated by ovarian hormones, Kruppel-like factor 5 (KLF5), a zinc finger-containing transcription factor, is persistently expressed in epithelial cells independently of ovarian hormones. Loss of uterine Klf5 causes female infertility due to defective implantation. Cox2 is normally expressed in the luminal epithelium and stroma at the site of blastocyst attachment, but luminal epithelial COX2 expression is absent with loss of Klf5. This is associated with the retention of the epithelium around the implantation chamber with arrested embryonic growth. These results suggest that Klf5 is indispensable for normal implantation.

title: (R)-N-(3-Methoxyphenyl)-tert-butanesulfinamide
abstract: The title compound, C11H17NO2S, was obtained by the reaction of (R)-tert-butanesulfinamide with 3-methoxyphenyl bromide in toluene. In the crystal, molecules interact head-to-tail through N—H⋯O and C—H⋯O hydrogen bonds, forming one-dimensional chains parallel to the a axis.

title: Sonographic evaluation of para- and perirenal fat thickness is an independent predictor of early kidney damage in obese patients
abstract: PurposeTo determine whether para- and perirenal fat ultrasonographic thickness (PFUT) is related to increased urinary albumin excretion and whether PFUT is an independent indicator of early kidney damage in obese subjects.MethodSixty-seven nonhypertensive, nondiabetic obese patients and 34 age- and sex-matched normal healthy volunteers were involved in this study. Clinical characteristics, blood biochemistry, PFUT, and urinary albumin/creatinine ratio (ACR) of the subjects were measured. The intraoperator and interoperator coefficient of variation was 5.6 and 3.2 %, respectively.ResultsACR and PFUT were significantly higher in obese patients than those of normal healthy volunteers. PFUT was higher in obese patients with microalbuminuria than those with normoalbuminuria. Correlation analysis showed PFUT had a positive correlation with body mass index (BMI, r = 0.677, P < 0.01), waist circumference (WC, r = 0.686, P < 0.01), plasma free fatty acids (FFAs, r = 0.589, P < 0.01), and ACR (r = 0.610, P < 0.01). ACR had a positive correlation with BMI (r = 0.444, P < 0.01), WC (r = 0.440, P < 0.01), and plasma FFAs (r = 0.496, P < 0.01). Multivariate regression analyses showed that ACR could be predicted by PFUT.ConclusionsPFUT may be an independent predictor of early kidney damage in nonhypertensive, nondiabetic obese patients, and PFUT could be a useful tool for the assessment of visceral fat and early kidney damage in obese patients.

title: Aspects of endocannabinoid signaling in periimplantation biology
abstract: Physiological roles of endocannabinoids, a group of endogenously produced cannabinoid-like lipid molecules that activate G protein-coupled cannabinoid receptors, are being increasingly appreciated in female reproduction. Adverse effects of cannabinoids on female fertility have been suspected for decades; however, underlying molecular and genetic bases by which they exert these effects were not clearly understood. The discovery of cannabinoid receptors (CB1 and CB2), endocannabinoid ligands (anandamide and 2-acylglycerol) as well as their key synthetic and hydrolytic pathways has helped to better understand the roles of cannabinoid/endocannabinoid signaling in preimplantation embryo development, oviductal embryo transport, embryo implantation and postimplantation embryonic growth. This review focuses on various aspects of the endocannabinoid system in female fertility based on studies that used knockout mouse models. The information generated from studies in mice is likely to shed deeper insight into fertility regulation in women.