Indeed, efforts to develop a low-cost, open-source alternative are still required to allow assembly of multiple genomes within a species to comparable contiguity. Despite being robust, the assembly algorithm used in these projects was closed-source, potentially limiting its application to the broader community.
Within months, a fully annotated, highly contiguous sequence was assembled, capturing the full organizational context of the 21 wheat chromosomes, some of which have been validated using other approaches. The wild emmer wheat, and subsequently the bread and durum wheat, genome projects used a whole-genome shotgun (WGS) approach based on Illumina short-read sequencing of shotgun libraries with multiple insert sizes. However, BAC-by-BAC assembly is laborious and time-consuming and has become an obsolete method of sequence assembly. Assembling bacterial artificial chromosomes (BACs) guided by a physical map yielded megabase-sized scaffolds, which were then arranged into chromosomal super-scaffolds (so-called pseudomolecules) by long-range linkage information afforded by ultra-dense genetic maps, chromosome conformation capture sequencing (Hi-C), or Bionano optical mapping. The genome projects of barley, bread wheat, and the A and D genome progenitors had initially followed the hierarchical shotgun approach as had been employed by the human genome project, but adopted second-generation sequencing methods for sequencing as they became available. dicoccoides (wild emmer wheat, AB genome). urartu (wheat A genome progenitor), and T. durum) as well as the wheat wild relatives Aegilops tauschii (wheat D genome progenitor), T. Recently, chromosome-scale reference sequence assemblies have come available for barley ( Hordeum vulgare), hexaploid bread wheat ( Triticum aestivum), and tetraploid durum wheat ( T. Large genome sizes, high content of transposable elements (TEs), and polyploidy (in the case of wheat) have long impeded genome assembly projects in the Triticeae. This study identifies a previously unappreciated enzymatic function of rapsyn and a role of neddylation in synapse formation, and reveals a potential target of therapeutic intervention for relevant neurological disorders.The Triticeae species wheat and barley were among the founder crops of Neolithic agriculture in Western Asia and continue to dominate agriculture in temperate regions of the world to the present day. Further biological and genetic studies support a working model where rapsyn, a classic scaffold protein, serves as an E3 ligase to induce AChR clustering and NMJ formation, possibly by regulation of AChR neddylation. Mutation of the RING domain that abolishes the enzyme activity inhibits rapsyn- as well as agrin-induced AChR clustering in heterologous and muscle cells. We show that the RING domain of rapsyn contains E3 ligase activity.
One such protein is rapsyn (receptor-associated protein at synapse), which is essential for acetylcholine receptor (AChR) clustering and NMJ (neuromuscular junction) formation. This is mediated by scaffold proteins that bridge the receptors with cytoskeleton. Neurotransmission is ensured by a high concentration of neurotransmitter receptors at the postsynaptic membrane.