UFMylation involves the covalent modification of substrate proteins with UFM1 (Ubiquitin-fold modifier 1) and is important for maintaining ER homeostasis. Stalled translation triggers the UFMylation of ER-bound ribosomes and activates C53-mediated autophagy to clear toxic polypeptides. C53 contains noncanonical shuffled ATG8-interacting motifs (sAIMs) that are essential for ATG8 interaction and autophagy initiation. However, the mechanistic basis of sAIM-mediated ATG8 interaction remains unknown. Here, we show that C53 and sAIMs are conserved across eukaryotes but secondarily lost in fungi and various algal lineages. Biochemical assays showed that the unicellular alga Chlamydomonas reinhardtii has a functional UFMylation pathway, refuting the assumption that UFMylation is linked to multicellularity. Comparative structural analyses revealed that both UFM1 and ATG8 bind sAIMs in C53, but in a distinct way. Conversion of sAIMs into canonical AIMs impaired binding of C53 to UFM1, while strengthening ATG8 binding. Increased ATG8 binding led to the autoactivation of the C53 pathway and sensitization of Arabidopsis thaliana to ER stress. Altogether, our findings reveal an ancestral role of sAIMs in UFMylation-dependent fine-tuning of C53-mediated autophagy activation.

Roots are highly plastic organs enabling plants to adapt to a changing below-ground environment. In addition to abiotic factors like nutrients or mechanical resistance, plant roots also respond to temperature variation. Below the heat stress threshold, Arabidopsis thaliana seedlings react to elevated temperature by promoting primary root growth, possibly to reach deeper soil regions with potentially better water saturation. While above-ground thermomorphogenesis is enabled by thermo-sensitive cell elongation, it was unknown how temperature modulates root growth. We here show that roots are able to sense and respond to elevated temperature independently of shoot-derived signals. This response is mediated by a yet unknown root thermosensor that employs auxin as a messenger to relay temperature signals to the cell cycle. Growth promotion is achieved primarily by increasing cell division rates in the root apical meristem, depending on de novo local auxin biosynthesis and temperature-sensitive organization of the polar auxin transport system. Hence, the primary cellular target of elevated ambient temperature differs fundamentally between root and shoot tissues, while the messenger auxin remains the same.

Purification through repeated column chromatography over silica gel and Sephadex LH-20 of the ethanol extract of the stems of Cissus aralioides (Baker) Planch. resulted in the isolation of a new ceramide, aralioidamide A (1) along with five known compounds (2-6). Their structures were determined by the extensive analysis of their spectroscopic (1D and 2D NMR) and spectrometric data, and comparison with those reported in the literature. Aralioidamide A (1) displayed weak antibacterial activity (MIC = 256 μg/mL) against Bacillus subtilis, Staphylococcus aureus and Shigella flexneri and was inactive (MIC > 256 μg/mL) against the tested fungi.

The cullin‐RING E3 ligases (CRLs) regulate diverse cellular processes in all eukaryotes. CRL activity is controlled by several proteins or protein complexes, including NEDD8, CAND1, and the CSN. Recently, a mammalian protein called Glomulin (GLMN) was shown to inhibit CRLs by binding to the RING BOX (RBX1) subunit and preventing binding to the ubiquitin‐conjugating enzyme. Here, we show that Arabidopsis ABERRANT LATERAL ROOT FORMATION4 (ALF4) is an ortholog of GLMN. The alf4 mutant exhibits a phenotype that suggests defects in plant hormone response. We show that ALF4 binds to RBX1 and inhibits the activity of SCFTIR1, an E3 ligase responsible for degradation of the Aux/IAA transcriptional repressors. In vivo, the alf4 mutation destabilizes the CUL1 subunit of the SCF. Reduced CUL1 levels are associated with increased levels of the Aux/IAA proteins as well as the DELLA repressors, substrate of SCFSLY1. We propose that the alf4 phenotype is partly due to increased levels of the Aux/IAA and DELLA proteins.

Rove beetles of the genus Stenus produce and store bioactive alkaloids like stenusine (3), 3‐(2‐methylbut‐1‐enyl)pyridine (4), and cicindeloine (5) in their pygidial glands to protect themselves from predation and microorganismic infestation.The biosynthesis of stenusine (3), 3‐(2‐methylbut‐1‐enyl)pyridine (4), and cicindeloine (5) was previously investigated in Stenus bimaculatus, Stenus similis, and Stenus solutus, respectively. The piperideine alkaloid cicindeloine (5) occurs also as a major compound in the pygidial gland secretion of Stenus cicindeloides. The three metabolites follow the same biosynthetic pathway, where the N‐heterocyclic ring is derived from L‐lysine and the side chain from L‐isoleucine. The different alkaloids are finally obtained by few modifications of shared precursor molecules, such as 2,3,4,5‐tetrahydro‐5‐(2‐methylbutylidene)pyridine (1). This piperideine alkaloid was synthesized and detected by GC/MS and GC at a chiral phase in the pygidial glands of Stenus similis, Stenus tarsalis, and Stenus cicindeloides.

Bacterial wilts of potato, tomato, pepper, and or eggplant caused by Ralstonia solanacearum are among the most serious plant diseases worldwide. In this study, the issue of developing bactericidal agents from natural sources against R. solanacearum derived from plant extracts was addressed. Extracts prepared from 25 plant species with antiseptic relevance in Egyptian folk medicine were screened for their antimicrobial properties against the potato pathogen R. solancearum by using the disc‐zone inhibition assay and microtitre plate dilution method. Plants exhibiting notable antimicrobial activities against the tested pathogen include extracts from Acacia arabica and Punica granatum. Bioactivity‐guided fractionation of A. arabica and P. granatum resulted in the isolation of bioactive compounds 3,5‐dihydroxy‐4‐methoxybenzoic acid and gallic acid, in addition to epicatechin. All isolates displayed significant antimicrobial activities against R. solanacearum (MIC values 0.5–9 mg/ml), with 3,5‐dihydroxy‐4‐methoxybenzoic acid being the most effective one with a MIC value of 0.47 mg/ml. We further performed a structure–activity relationship (SAR) study for the inhibition of R. solanacearum growth by ten natural, structurally related benzoic acids.

Two new N ‐glucosylated indole alkaloids were isolated from fruiting bodies of the basidiomycete Cortinarius brunneus (Pers .) Fr . The structures were elucidated by means of the spectroscopic data. Additionally, the very recently reported compounds N‐ 1‐β‐ glucopyranosyl‐3‐(carboxymethyl)‐1H ‐indole (3 ) and N‐ 1‐β‐ glucopyranosyl‐3‐(2‐methoxy‐2‐oxoethyl)‐1H ‐indole (4 ) could be detected. Compound 3 is the N ‐glucoside of the plant‐growth regulator 1H ‐indole‐3‐acetic acid (IAA), but, in contrast, it does not exhibit auxin‐like activity in an Arabidopsis thaliana tap root elongation assay.

A short survey of historic and current methods for the synthesis of selenocysteine, selenocystine, and derivatives and related compounds is presented, with an additional emphasis on the formation of selenocysteine‐derived SeS bridges. The majority of methods to the amino acid starts with protected and O ‐activated serine, but also other concepts are included such as radical or multicomponent strategies, the latter allowing also direct access to peptoids in one pot. Of special importance is the monomeric oxidative cyclization of selenocysteine–cysteine peptides to eight‐membered and larger rings with a selenenylsulfide bridge, a crucial element in several selenoproteins.

New, partially acetylated dihydroxy fatty acids could be identified in the floral oil of Malpighia coccigera (Malpighiaceae): 7‐OAc,3‐OH 20 : 0, 7‐OAc,3‐OH 22 : 0, 9‐OAc,3‐OH 22 : 0, 9‐OAc,5‐OH 22 : 0, 3,9‐diOAc 22 : 0, 9‐OAc,3‐OH 24 : 0 , and 11‐OAc,5‐OH 24 : 0 . The substitution patterns of all hitherto undescribed dihydroxylated and additionally identified monohydroxylated fatty acids are in agreement with a polyketide analogous biosynthesis. Intermediates may be 3‐acetoxy fatty acids (C16, C18, and C20), known from flower secretions of other phylogenetically unrelated plant families. A possible relationship between plant epicuticular wax and floral oil biosynthesis is discussed. It may explain why an independent but convergent development of oil flowers and flower oils in unrelated plant families was possible.

Natural hammerhead ribozymes are mostly found in some viroid and viroid‐like RNAs and catalyze their cis cleavage during replication. Hammerheads have been manipulated to act in trans and assumed to have a similar catalytic behavior in this artificial context. However, we show here that two natural cis‐acting hammerheads self‐cleave much faster than trans‐acting derivatives and other reported artificial hammerheads. Moreover, modifications of the peripheral loops 1 and 2 of one of these natural hammerheads induced a >100‐fold reduction of the self‐cleavage constant, whereas engineering a trans‐acting artificial hammerhead into a cis derivative by introducing a loop 1 had no effect. These data show that regions external to the central conserved core of natural hammerheads play a role in catalysis, and suggest the existence of tertiary interactions between these peripheral regions. The interactions, determined by the sequence and size of loops 1 and 2 and most likely of helices I and II, must result from natural selection and should be studied in order to better understand the hammerhead requirements in vivo.