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Fulltext Graph Theoretical Methods and Workflows for Searching and Annotation of RNA Tertiary Base Motifs and Substructures

Emrizal R, Hamdani HY, Firdaus-Raih M

Int J Mol Sci, 2021 Aug 09;22(16).
PMID: 34445259 DOI: 10.3390/ijms22168553

The increasing number and complexity of structures containing RNA chains in the Protein Data Bank (PDB) have led to the need for automated structure annotation methods to replace or complement expert visual curation. This is especially true when searching for tertiary base motifs and substructures. Such base arrangements and motifs have diverse roles that range from contributions to structural stability to more direct involvement in the molecule's functions, such as the sites for ligand binding and catalytic activity. We review the utility of computational approaches in annotating RNA tertiary base motifs in a dataset of PDB structures, particularly the use of graph theoretical algorithms that can search for such base motifs and annotate them or find and annotate clusters of hydrogen-bond-connected bases. We also demonstrate how such graph theoretical algorithms can be integrated into a workflow that allows for functional analysis and comparisons of base arrangements and sub-structures, such as those involved in ligand binding. The capacity to carry out such automatic curations has led to the discovery of novel motifs and can give new context to known motifs as well as enable the rapid compilation of RNA 3D motifs into a database.

Matched MeSH terms: Nucleotide Motifs*
Fulltext Complete Genome Sequence and Methylome Analysis of Aeromonas hydrophila Strain YL17, Isolated from a Compost Pile

Lim YL, Roberts RJ, Ee R, Yin WF, Chan KG

Genome Announc, 2016 Mar 03;4(2).
PMID: 26941143 DOI: 10.1128/genomeA.00060-16

In this report, we announce the complete genome sequence of Aeromonas hydrophila strain YL17. Single-molecule real-time (SMRT) DNA sequencing was used to generate the complete genome sequence and the genome-wide DNA methylation profile of this environmental isolate. A total of five unique DNA methyltransferase recognition motifs were reported here.

Matched MeSH terms: Nucleotide Motifs
Fulltext Population structure of the blood clam (Tegillarca granosa) in China based on microsatellite markers

Wang YJ, Zeng QG, Xu LN

Genet. Mol. Res., 2013;12(2):892-900.
PMID: 23613236 DOI: 10.4238/2013.April.2.6

The blood clam, Tegillarca granosa, is widely cultivated in China. We isolated 6 microsatellite loci from T. granosa and used them to investigate genetic diversity and population structure of 5 widely distributed populations of blood clam collected from eastern and southeastern China. The allele number per locus varied from 4 to 9, and the polymorphism information content value was 0.301 to 0.830. The mean observed and expected heterozygosities varied from 0.304 to 0.460 and 0.556 to 0.621, respectively; the population from Yueqing had the smallest observed heterozygosity. In the neighbor-joining tree, Shandong, Fenghua and Yueqing populations clustered together, and there was geographic divergence between Shandong and Guangxi populations. Some microsatellite loci that were isolated from these mainland China samples were not found in blood clams collected from Malaysia.

Matched MeSH terms: Nucleotide Motifs
Fulltext NASSAM: a server to search for and annotate tertiary interactions and motifs in three-dimensional structures of complex RNA molecules

Hamdani HY, Appasamy SD, Willett P, Artymiuk PJ, Firdaus-Raih M

Nucleic Acids Res, 2012 Jul;40(Web Server issue):W35-41.
PMID: 22661578 DOI: 10.1093/nar/gks513

Similarities in the 3D patterns of RNA base interactions or arrangements can provide insights into their functions and roles in stabilization of the RNA 3D structure. Nucleic Acids Search for Substructures and Motifs (NASSAM) is a graph theoretical program that can search for 3D patterns of base arrangements by representing the bases as pseudo-atoms. The geometric relationship of the pseudo-atoms to each other as a pattern can be represented as a labeled graph where the pseudo-atoms are the graph's nodes while the edges are the inter-pseudo-atomic distances. The input files for NASSAM are PDB formatted 3D coordinates. This web server can be used to identify matches of base arrangement patterns in a query structure to annotated patterns that have been reported in the literature or that have possible functional and structural stabilization implications. The NASSAM program is freely accessible without any login requirement at http://mfrlab.org/grafss/nassam/.

Matched MeSH terms: Nucleotide Motifs
Fulltext Comparative sequence and structure analysis reveals the conservation and diversity of nucleotide positions and their associated tertiary interactions in the riboswitches

Appasamy SD, Ramlan EI, Firdaus-Raih M

PLoS One, 2013;8(9):e73984.
PMID: 24040136 DOI: 10.1371/journal.pone.0073984

The tertiary motifs in complex RNA molecules play vital roles to either stabilize the formation of RNA 3D structure or to provide important biological functionality to the molecule. In order to better understand the roles of these tertiary motifs in riboswitches, we examined 11 representative riboswitch PDB structures for potential agreement of both motif occurrences and conservations. A total of 61 unique tertiary interactions were found in the reference structures. In addition to the expected common A-minor motifs and base-triples mainly involved in linking distant regions the riboswitch structures three highly conserved variants of A-minor interactions called G-minors were found in the SAM-I and FMN riboswitches where they appear to be involved in the recognition of the respective ligand's functional groups. From our structural survey as well as corresponding structure and sequence alignments, the agreement between motif occurrences and conservations are very prominent across the representative riboswitches. Our analysis provide evidence that some of these tertiary interactions are essential components to form the structure where their sequence positions are conserved despite a high degree of diversity in other parts of the respective riboswitches sequences. This is indicative of a vital role for these tertiary interactions in determining the specific biological function of riboswitch.

Matched MeSH terms: Nucleotide Motifs
Transcriptogenomics identification and characterization of RNA editing sites in human primary monocytes using high-depth next generation sequencing data

Leong WM, Ripen AM, Mirsafian H, Mohamad SB, Merican AF

Genomics, 2019 07;111(4):899-905.
PMID: 29885984 DOI: 10.1016/j.ygeno.2018.05.019

High-depth next generation sequencing data provide valuable insights into the number and distribution of RNA editing events. Here, we report the RNA editing events at cellular level of human primary monocyte using high-depth whole genomic and transcriptomic sequencing data. We identified over a ten thousand putative RNA editing sites and 69% of the sites were A-to-I editing sites. The sites enriched in repetitive sequences and intronic regions. High-depth sequencing datasets revealed that 90% of the canonical sites were edited at lower frequencies (<0.7). Single and multiple human monocytes and brain tissues samples were analyzed through genome sequence independent approach. The later approach was observed to identify more editing sites. Monocytes was observed to contain more C-to-U editing sites compared to brain tissues. Our results establish comparable pipeline that can address current limitations as well as demonstrate the potential for highly sensitive detection of RNA editing events in single cell type.

Matched MeSH terms: Nucleotide Motifs
Fulltext Characterisation of full-length cDNA sequences provides insights into the Eimeria tenella transcriptome

Amiruddin N, Lee XW, Blake DP, Suzuki Y, Tay YL, Lim LS, et al.

BMC Genomics, 2012 Jan 13;13:21.
PMID: 22244352 DOI: 10.1186/1471-2164-13-21

BACKGROUND: Eimeria tenella is an apicomplexan parasite that causes coccidiosis in the domestic fowl. Infection with this parasite is diagnosed frequently in intensively reared poultry and its control is usually accorded a high priority, especially in chickens raised for meat. Prophylactic chemotherapy has been the primary method used for the control of coccidiosis. However, drug efficacy can be compromised by drug-resistant parasites and the lack of new drugs highlights demands for alternative control strategies including vaccination. In the long term, sustainable control of coccidiosis will most likely be achieved through integrated drug and vaccination programmes. Characterisation of the E. tenella transcriptome may provide a better understanding of the biology of the parasite and aid in the development of a more effective control for coccidiosis.
RESULTS: More than 15,000 partial sequences were generated from the 5' and 3' ends of clones randomly selected from an E. tenella second generation merozoite full-length cDNA library. Clustering of these sequences produced 1,529 unique transcripts (UTs). Based on the transcript assembly and subsequently primer walking, 433 full-length cDNA sequences were successfully generated. These sequences varied in length, ranging from 441 bp to 3,083 bp, with an average size of 1,647 bp. Simple sequence repeat (SSR) analysis identified CAG as the most abundant trinucleotide motif, while codon usage analysis revealed that the ten most infrequently used codons in E. tenella are UAU, UGU, GUA, CAU, AUA, CGA, UUA, CUA, CGU and AGU. Subsequent analysis of the E. tenella complete coding sequences identified 25 putative secretory and 60 putative surface proteins, all of which are now rational candidates for development as recombinant vaccines or drug targets in the effort to control avian coccidiosis.
CONCLUSIONS: This paper describes the generation and characterisation of full-length cDNA sequences from E. tenella second generation merozoites and provides new insights into the E. tenella transcriptome. The data generated will be useful for the development and validation of diagnostic and control strategies for coccidiosis and will be of value in annotation of the E. tenella genome sequence.

Matched MeSH terms: Nucleotide Motifs