Draga, S. | Search bioRxiv

bioRxiv2026

The BUD13 splicing regulator: transcript structure and expression in ovules of sexual and apomictic Paspalum notatum

Background and AimsPaspalum notatum reproduces through either sexuality or apomixis, two pathways that may coexist within the same individual and are regulated by interconnected molecular networks responsive to environmental cues. Here, we characterized the transcript structure and expression of BUD SITE SELECTION PROTEIN 13 (BUD13), a component of the RES spliceosomal complex previously reported as differentially expressed in florets of sexual and apomictic plants, as a first step toward testing its involvement in the molecular regulation of the apomixis-sexuality switch. MethodsPreviously generated floral and leaf transcriptomes from sexual and apomictic Paspalum notatum plants, including Oxford Nanopore long-read data, were mined to characterize BUD13 transcript structure and expression. Phylogenetic analyses and in silico mapping were conducted to infer evolutionary relationships and determine the origin of the transcripts. Differential expression was validated by RT-qPCR, while in situ hybridization was used to reveal cell-specific ovule expression patterns. Key resultsBUD13 is expressed in Paspalum notatum florets as a truncated isoform (SHORT) encoding a small protein lacking part of the herpes simplex virus regulatory protein (ICP4) domain. Two SHORT transcripts, SHORT1 and SHORT2, with different 5' untranslated region (UTR) regions, were identified in flowers. SHORT1 was consistently upregulated in apomictic ovules from premeiosis to anthesis. Both transcripts originated from a single genomic locus located in the subtelomeric region of the short arm of chromosome 6. SHORT isoforms with variable structures were detected in other monocots. In situ hybridization showed that, whereas BUD13 was expressed throughout sexual ovules, expression was absent from the female germline of apomictic ovules. A consistent expression was observed in somatic proembryos of aposporous embryo sacs. ConclusionsOur findings reveal structural, spatial and temporal divergence in BUD13 expression between sexual and apomictic reproductive programs, providing new insights into the molecular regulation of asexual seed formation.

plant biology↗

bioRxiv2024

CACHE Challenge #1: targeting the WDR domain of LRRK2, a Parkinson's Disease associated protein.

The CACHE challenges are a series of prospective benchmarking exercises meant to evaluate progress in the field of computational hit-finding. Here we report the results of the inaugural CACHE #1 challenge in which 23 computational teams each selected up to 100 commercially available compounds that they predicted would bind to the WDR domain of the Parkinsons disease target LRRK2, a domain with no known ligand and only an apo structure in the PDB. The lack of known binding data and presumably low druggability of the target is a challenge to computational hit finding methods. Seventy-three of the 1955 procured molecules bound LRRK2 in an SPR assay with KD lower than 150 M and were advanced to a hit expansion phase where computational teams each selected up to 50 analogs each. Binding was observed in two orthogonal assays with affinities ranging from 18 to 140 M for seven chemically diverse series. The seven successful computational workflows varied in their screening strategies and techniques. Three used molecular dynamics to produce a conformational ensemble of the targeted site, three included a fragment docking step, three implemented a generative design strategy and five used one or more deep learning steps. CACHE #1 reflects a highly exploratory phase in computational drug design where participants sometimes adopted strikingly diverging screening strategies. Machine-learning accelerated methods achieved similar results to brute force (e.g. exhaustive) docking. First-in-class, experimentally confirmed compounds were rare and weakly potent, indicating that recent advances are not sufficient to effectively address challenging targets.

biochemistry↗