Phylogenetic and Evolutionary Analysis of Plant Small RNA 2'-O-Methyltransferase (HEN1) Protein Family

HUA ENHANCER 1 (HEN1) is a pivotal mediator in protecting sRNAs from 3'-end uridylation and 3' to 5' exonuclease-mediated degradation in plants. Here, we investigated the pattern of the HEN1 protein family evolutionary history and possible relationships in the plant lineages using protein sequence analyses and conserved motifs composition, functional domain identification, architecture, and phylogenetic tree reconstruction and evolutionary history inference. According to our results, HEN1 protein sequences bear several highly conserved motifs in plant species retained during the evolution from their ancestor. However, several motifs are present only in Gymnosperms and Angiosperms. A similar trend showed for their domain architecture. At the same time, phylogenetic analysis revealed the grouping of the HEN1 proteins in the three main super clads. In addition, the Neighbor-net network analysis result provides some nodes have multiple parents indicating a few conflicting signals in the data, which is not the consequence of sampling error, the effect of the selected model, or the estimation method. By reconciling the protein and species tree, we considered the gene duplications in several given species and found 170 duplication events in the evolution of HEN1 in the plant lineages. According to our analysis, the main HEN1 superclass mostly showed orthologous sequences that illustrate the vertically transmitting of HEN1 to the main lines. However, in both orthologous and paralogs, we predicted insignificant structural deviations. Our analysis implies that small local structural changes that occur continuously during the folds can moderate the changes created in the sequence. According to our results, we proposed a hypothetical model and evolutionary trajectory for the HEN1 protein family in the plant kingdom.

Synthaser: a CD-Search enabled Python toolkit for analysing domain architecture of fungal secondary metabolite megasynth(et)ases

BACKGROUND

Fungi are prolific producers of secondary metabolites (SMs), which are bioactive small molecules with important applications in medicine, agriculture and other industries. The backbones of a large proportion of fungal SMs are generated through the action of large, multi-domain megasynth(et)ases such as polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs). The structure of these backbones is determined by the domain architecture of the corresponding megasynth(et)ase, and thus accurate annotation and classification of these architectures is an important step in linking SMs to their biosynthetic origins in the genome.

RESULTS

Here we report synthaser, a Python package leveraging the NCBI's conserved domain search tool for remote prediction and classification of fungal megasynth(et)ase domain architectures. Synthaser is capable of batch sequence analysis, and produces rich textual output and interactive visualisations which allow for quick assessment of the megasynth(et)ase diversity of a fungal genome. Synthaser uses a hierarchical rule-based classification system, which can be extensively customised by the user through a web application ( http://gamcil.github.io/synthaser ). We show that synthaser provides more accurate domain architecture predictions than comparable tools which rely on curated profile hidden Markov model (pHMM)-based approaches; the utilisation of the NCBI conserved domain database also allows for significantly greater flexibility compared to pHMM approaches. In addition, we demonstrate how synthaser can be applied to large scale genome mining pipelines through the construction of an Aspergillus PKS similarity network.

CONCLUSIONS

Synthaser is an easy to use tool that represents a significant upgrade to previous domain architecture analysis tools. It is freely available under a MIT license from PyPI ( https://pypi.org/project/synthaser ) and GitHub ( https://github.com/gamcil/synthaser ).

ProdMX: Rapid query and analysis of protein functional domain based on compressed sparse matrices

Large-scale protein analysis has been used to characterize large numbers of proteins across numerous species. One of the applications is to use as a high-throughput screening method for pathogenicity of genomes. Unlike sequence homology methods, protein comparison at a functional level provides us with a unique opportunity to classify proteins, based on their functional structures without dealing with sequence complexity of distantly related species. Protein functions can be abstractly described by a set of protein functional domains, such as PfamA domains; a set of genomes can then be mapped to a matrix, with each row representing a genome, and the columns representing the presence or absence of a given functional domain. However, a powerful tool is needed to analyze the large sparse matrices generated by millions of genomes that will become available in the near future. The ProdMX is a tool with user-friendly utilities developed to facilitate high-throughput analysis of proteins with an ability to be included as an effective module in the high-throughput pipeline. The ProdMX employs a compressed sparse matrix algorithm to reduce computational resources and time used to perform the matrix manipulation during functional domain analysis. The ProdMX is a free and publicly available Python package which can be installed with popular package mangers such as PyPI and Conda, or with a standard installer from source code available on the ProdMX GitHub repository at https://github.com/visanuwan/prodmx.

Post-translational Modifications of Serine/Threonine and Histidine Kinases and Their Roles in Signal Transductions in Synechocystis Sp. PCC 6803

Cyanobacterium Synechocystis sp. PCC 6803, a popular model organism for researches in photosynthesis and biofuel production, contains plant-like photosynthetic machineries which significantly contribute to global carbon fixation. There are 12 eukaryotic-type Ser/Thr kinases (SpkA-L) and 49 His kinases (Hik1-49) of two-component systems in the genome of Synechocystis sp. PCC 6803. They are the key regulators in sensing and transmitting stimuli including light- and glucose-mediate signal transduction. Proteomic studies were able to identify all the kinases. The majority of kinases no matter whether they have a predicted transmembrane domain were identified in the membrane fractions. Six Ser/Thr kinases (SpkA-D, F and G) and ten His kinases (Hik4, 12, 14, 21, 26-27, 29, 36, 43, and 46) were identified to have one or more of the three types of post-translational modifications: phosphorylation, acetylation, and thiol oxidation. Interestingly, SpkG has the phosphorylatable threonine residue that was aligned with the phosphorylated threonine residue in the activation loop of human CDK7, demonstrating conserved phosphorylation between cyanobacterial and human kinases. Transcriptomics and proteomics revealed differential expression of the kinases in heterotrophic and photoheterotrophic compared with photoautotrophic conditions, indicating their roles in regulating the growth modes of cyanobacteria. In summary, this review focuses on the discussions on post-transcriptional modifications, transcriptomic, and proteomic studies of Ser/Thr and His kinases. This together with our published review in 2019 present a complete story of an overview of sequences, domain architectures, and biochemical and physiological functions of cyanobacterial kinases with adequate details in the context of high throughput systems. We also emphasize the importance of discovering upstream molecules and substrates to understand the exact functions of the kinases in vivo. As an attempt, a model is proposed in which Hik31, His33, Sll1334, and IcfG are hypothesized to be critical for switching between autotrophic and heterotrophic modes based on the results from the phenotypes of the gene knockout strains combined with their post-translational modifications, and gene expression profiles.

Genome-wide identification and characterization of multiple C2 domains and transmembrane region proteins in Gossypium hirsutum

Background

Multiple C2 domains and transmembrane region proteins (MCTPs) may act as transport mediators of other regulators. Although increased number of MCTPs in higher plants implies their diverse and specific functions in plant growth and development, only a few plant MCTPs have been studied and no study on the MCTPs in cotton has been reported.

Results

In this study, we identified 31 MCTPs in G. hirsutum, which were classified into five subfamilies according to the phylogenetic analysis. GhMCTPs from subfamily V exhibited isoelectric points (pIs) less than 7, whereas GhMCTPs from subfamily I, II, III and IV exhibited pIs more than 7.5, implying their distinct biological functions. In addition, GhMCTPs within subfamily III, IV and V exhibited more diverse physicochemical properties, domain architectures and expression patterns than GhMCTPs within subfamily I and II, suggesting that GhMCTPs within subfamily III, IV and V diverged to perform more diverse and specific functions. Analyses of conserved motifs and pIs indicated that the N-terminus was more divergent than the C-terminus and GhMCTPs’ functional divergence might be mainly contributed by the N-terminus. Furthermore, yeast two-hybrid assay indicated that the N-terminus was responsible to interact with target proteins. Phylogenetic analysis classified multiple N-terminal C2 domains into four subclades, suggesting that these C2 domains performed different molecular functions in mediating the transport of target proteins.

Conclusions

Our systematic characterization of MCTPs in G. hirsutum will provide helpful information to further research GhMCTPs’ molecular roles in mediating other regulators’ transport to coordinate growth and development of various cotton tissues.

Evolutionary relationships between the transcriptional repressors of the polyhydroxyalkanoate reserve storage system in prokaryotes: Conserved but phylogenetically heterogeneous

Bacteria and archaea accumulate cytoplasmic polyhydroxyalkanoate (PHA) granules under nutrient-limited conditions with excess carbon. The transcriptional regulatory (TR) proteins found on the surface of PHA granules act as repressors as well as activators for the expression of major surface proteins called phasins. Until now, detailed information on the evolutionary relationships between these transcription regulators has not been available. Here, we conducted homology searches and analyzed information available for the domains and protein families of the TR proteins through phylogenetic studies. A total of 282 TR proteins were identified and further classified into four distinct subfamilies based upon the presence of conserved motifs: PHB_acc, TetR-like, AbrB-like, and PadR-like. Depending upon the particular family, the DNA-binding domains were located at either the N- or C-terminus. Our results indicated that TR proteins containing the PHB_acc domain are highly conserved within the bacteria, while other TR proteins are present only within archaea (AbrB-like), gram positive bacteria (PadR-like), or the Pseudomonas genera (TetR-like). The repression domains are charged, hydrophobic, and rich in leucine or glutamine. In phylogenetic analyses, many groups of TR proteins were clustered together according to identical domain architectures showing the independent origins of the TR proteins in the PHA reserve storage system. Further analyses revealed that the TR proteins have experienced multiple gene duplications across prokaryotes. Thus, this study investigated the evolutionary framework of TR proteins and has provided a comprehensive catalog of TR proteins for ongoing studies to characterize the functions of these proteins within diverse organisms.

Classification of human Herpesviridae proteins using Domain-architecture Aware Inference of Orthologs (DAIO)

We developed a computational approach called Domain-architecture Aware Inference of Orthologs (DAIO) for the analysis of protein orthology by combining phylogenetic and protein domain-architecture information. Using DAIO, we performed a systematic study of the proteomes of all human Herpesviridae species to define Strict Ortholog Groups (SOGs). In addition to assessing the taxonomic distribution for each protein based on sequence similarity, we performed a protein domain-architecture analysis for every protein family and computationally inferred gene duplication events. While many herpesvirus proteins have evolved without any detectable gene duplications or domain rearrangements, numerous herpesvirus protein families do exhibit complex evolutionary histories. Some proteins acquired additional domains (e.g., DNA polymerase), whereas others show a combination of domain acquisition and gene duplication (e.g., betaherpesvirus US22 family), with possible functional implications. This novel classification system of SOGs for human Herpesviridae proteins is available through the Virus Pathogen Resource (ViPR, www.viprbrc.org).

PCC 6803

The cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis) is a photoautotrophic prokaryote with plant-like photosynthetic machineries which significantly contribute to global carbon fixation and atmospheric oxygen production. Because of the relatively short cell doubling time, small size of the genome, and the ease for genetic manipulation, Synechocystis is a popular model organism for studies including photosynthesis and biofuel production. The cyanobacterium contains 12 eukaryotic type Ser/Thr kinases (SpkA-L) and 49 histidine kinases (Hik1-47 and Sll1334 and Sll5060 are named as Hik48 and Hik49, respectively, in this review) of the two-component system. All SpkA-L kinases have a eukaryotic kinase DFG signature in their A-loops. Based on the types of the kinase domains, the Spks can be separated into three groups: one group contains SpkA and SpkG which are related to human kinases, while SpkH-L are in another group that is distinct from human kinases. The third group contains SpkB-F which are between the first two groups. Four histidine kinases (Hiks17, 36, 45, and 48) lack a clear histidine kinase domain, and the conserved phosphorylatable histidine residue could not be identified for six histidine kinases (Hiks11, 18, 29, 37, 39, and 43) even though they have clear histidine kinase domains. Each of the remaining 39 has a histidine kinase domain with the conserved histidine residue. Eight hybrid histidine kinases contain one or two receiver domains, and they all, except Hik25 (Slr0222), have the conserved phosphorylatable aspartate. The disruptants of all kinases except hik13 and hik15 have been generated, and the majority of them have modest or no obvious phenotypes, indicating other kinases could functionally compensate the loss of a particular kinase. This review presents a comprehensive discussion including a spectrum of sequence, domain architecture, in vivo function, and proteomics investigations of Ser/Thr and histidine kinases. Understanding the sequences, domain architectures, and biology of the kinases will help to integrate "omic" data to clarify their exact biochemical functions.

Evolutionary relationships and expression analysis of EUL domain proteins in rice (Oryza sativa)

BACKGROUND

Lectins, defined as 'Proteins that can recognize and bind specific carbohydrate structures', are widespread among all kingdoms of life and play an important role in various biological processes in the cell. Most plant lectins are involved in stress signaling and/or defense. The family of Euonymus-related lectins (EULs) represents a group of stress-related lectins composed of one or two EUL domains. The latter protein domain is unique in that it is ubiquitous in land plants, suggesting an important role for these proteins.

RESULTS

Despite the availability of multiple completely sequenced rice genomes, little is known on the occurrence of lectins in rice. We identified 329 putative lectin genes in the genome of Oryza sativa subsp. japonica belonging to nine out of 12 plant lectin families. In this paper, an in-depth molecular characterization of the EUL family of rice was performed. In addition, analyses of the promoter sequences and investigation of the transcript levels for these EUL genes enabled retrieval of important information related to the function and stress responsiveness of these lectins. Finally, a comparative analysis between rice cultivars and several monocot and dicot species revealed a high degree of sequence conservation within the EUL domain as well as in the domain organization of these lectins.

CONCLUSIONS

The presence of EULs throughout the plant kingdom and the high degree of sequence conservation in the EUL domain suggest that these proteins serve an important function in the plant cell. Analysis of the promoter region of the rice EUL genes revealed a diversity of stress responsive elements. Furthermore analysis of the expression profiles of the EUL genes confirmed that they are differentially regulated in response to several types of stress. These data suggest a potential role for the EULs in plant stress signaling and defense.

Genome-wide identification and domain organization of lectin domains in cucumber

Lectins are ubiquitous proteins in plants and play important roles in a diverse set of biological processes, such as plant defense and cell signaling. Despite the availability of the Cucumis sativus L. genome sequence since 2009, little is known with respect to the occurrence of lectins in cucumber. In this study, a total of 146 putative lectin genes belonging to 10 different lectin families were identified and localized in the cucumber genome. Domain architecture analysis revealed that most of these lectin gene sequences contain multiple domains, where lectin domains are linked with other domains, as such creating chimeric lectin sequences encoding proteins with dual activities. This study provides an overview of lectin motifs in cucumber and will help to understand their potential biological role(s).

Computational Analysis of the Domain Architecture and Substrate-Gating Mechanism of Prolyl Oligopeptidases from Shewanella woodyi and Identification of Probable Lead Molecules

Prolyl oligopeptidases (POPs) are serine proteases found in prokaryotes and eukaryotes which hydrolyze the peptide bond containing proline. The current study focuses on the analysis of POP sequences, their distribution and domain architecture in Shewanella woodyi, a Gram-negative, luminous bacterium which causes celiac sprue and similar infections in marine organisms. The POP undergoes huge interdomain movement, which allows possible route for the entry of any substrate. Hence, it offers an opportunity to understand the mechanism of substrate gating by studying the domain architecture and possibility to identify a probable drug target. In the present study, the POP sequence was retrieved from GenBank database and the best homologous templates were identified by PSI-BLAST search. The three-dimensional structures of the closed and open forms of POP from S. woodyi, which are not available in native form, were generated by homology modeling. The ideal lead molecules were screened by computer-aided virtual screening, and the binding potential of the best leads toward the target was studied by molecular docking. The domain architecture of the POP revealed that it has a propeller domain consists of [Formula: see text]-sheets, surrounded by [Formula: see text]-helices and [Formula: see text] hydrolase domain with catalytic triad containing Ser-564, Asp-646 and His-681. The hypothetical models of open and closed POP showed backbone RMSD value of 0.56 and 0.65 Å, respectively. Ramachandran plot of the open and closed POP conformations accounts for 99.4 and 98.7 % residues in the favoured region, respectively. Our study revealed that propeller domain comes as an insert between N-terminal and C-terminal [Formula: see text] hydrolase domain. Molecular docking, drug likeness properties and ADME prediction suggested that KUC-103481N and Pramiracetum can be used as probable lead molecules toward the POP from S. woodyi.

An evolutionary roadmap to the microtubule-associated protein MAP Tau

BACKGROUND

The microtubule associated protein Tau (MAPT) promotes assembly and interaction of microtubules with the cytoskeleton, impinging on axonal transport and synaptic plasticity. Its neuronal expression and intrinsic disorder implicate it in some 30 tauopathies such as Alzheimer's disease and frontotemporal dementia. These pathophysiological studies have yet to be complemented by computational analyses of its molecular evolution and structural models of all its functional domains to explain the molecular basis for its conservation profile, its site-specific interactions and the propensity to conformational disorder and aggregate formation.

RESULTS

We systematically annotated public sequence data to reconstruct unspliced MAPT, MAP2 and MAP4 transcripts spanning all represented genomes. Bayesian and maximum likelihood phylogenetic analyses, genetic linkage maps and domain architectures distinguished a nonvertebrate outgroup from the emergence of MAP4 and its subsequent ancestral duplication to MAP2 and MAPT. These events were coupled to other linked genes such as KANSL1L and KANSL and may thus be consequent to large-scale chromosomal duplications originating in the extant vertebrate genomes of hagfish and lamprey. Profile hidden Markov models (pHMMs), clustered subalignments and 3D structural predictions defined potential interaction motifs and specificity determining sites to reveal distinct signatures between the four homologous microtubule binding domains and independent divergence of the amino terminus.

CONCLUSION

These analyses clarified ambiguities of MAPT nomenclature, defined the order, timing and pattern of its molecular evolution and identified key residues and motifs relevant to its protein interaction properties and pathogenic role. Additional unexpected findings included the expansion of cysteine-containing, microtubule binding domains of MAPT in cold adapted Antarctic icefish and the emergence of a novel multiexonic saitohin (STH) gene from repetitive elements in MAPT intron 11 of certain primate genomes.

An alignment-free domain architecture similarity search (ADASS) algorithm for inferring homology between multi-domain proteins

Annotations of the genes and their products are largely guided by inferring homology. Sequence similarity is the primary measure used for annotation purpose however, the domain content and order were given less importance albeit the fact that domain insertion, deletion, positional changes can bring in functional varieties. Of late, several methods developed quantify domain architecture similarity depending on alignments of their sequences and are focused on only homologous proteins. We present an alignment-free domain architecture-similarity search (ADASS) algorithm that identifies proteins that share very poor sequence similarity yet having similar domain architectures. We introduce a “singlet matching-triplet comparison” method in ADASS, wherein triplet of domains is compared with other triplets in a pair-wise comparison of two domain architectures. Different events in the triplet comparison are scored as per a scoring scheme and an average pairwise distance score (Domain Architecture Distance score - DAD Score) is calculated between protein domains architectures. We use domain architectures of a selected domain termed as centric domain and cluster them based on DAD score. The algorithm has high Positive Prediction Value (PPV) with respect to the clustering of the sequences of selected domain architectures. A comparison of domain architecture based dendrograms using ADASS method and an existing method revealed that ADASS can classify proteins depending on the extent of domain architecture level similarity. ADASS is more relevant in cases of proteins with tiny domains having little contribution to the overall sequence similarity but contributing significantly to the overall function.