Authors: AG McArthur, N Waglechner, F Nizam, A Yan, MA Azad, AJ Baylay, K Bhullar, MJ Canova, G De Pascale, L Ejim, L Kalan, AM King, K Koteva, M Morar, MR Mulvey, JS O’Brien, AC Pawlowski, LJV Piddock, P Spanogiannopoulos, AD Sutherland, I Tang, PL Taylor, M Thaker, W Wang, M Yan, T Yu, & GD Wright
Antimicrobial Agents & Chemotherapy, 2013, 57(7): 3348-57.
The field of antibiotic drug discovery and the monitoring of new antibiotic resistance elements have yet to fully exploit the power of the genome revolution. Despite the fact that the first genomes sequenced of free living organisms were those of bacteria, there have been few specialized bioinformatic tools developed to mine the growing amount of genomic data associated with pathogens. In particular, there are few tools to study the genetics and genomics of antibiotic resistance and how it impacts bacterial populations, ecology, and the clinic. We have initiated development of such tools in the form of the Comprehensive Antibiotic Research Database (CARD; http://arpcard.mcmaster.ca). The CARD integrates disparate molecular and sequence data, provides a unique organizing principle in the form of the Antibiotic Resistance Ontology (ARO), and can quickly identify putative antibiotic resistance genes in new unannotated genome sequences. This unique platform provides an informatic tool that bridges antibiotic resistance concerns in health care, agriculture, and the environment.
Authors: PV Tedom, R Kieft, AG McArthur, W Mbacham, D Mark Welch, SL Hajduk, VPK Titanji
Asian Pacific Journal of Tropical Disease, 2012, 2(5): 342-347.
Objective: To understand the spread of drug resistance and identifying diagnostic probes among the local tuberculosis (TB) strains in order to design rational control tools for tuberculosis controls. Methods: TA cloning and sequencing were used to characterize mutation associated with RIF resistance in 69 bp region of the gene, rpoB. The analysis identified two regions of mutations but no unusual insertion and deletion. No mutation was observed in RIF sensitive strains. Results: We employed Random Amplified Polymorphic DNA (RAPD) analysis for typing strains of M. tuberculosis to determine whether new strains were present among M. tuberculosis isolates circulating in Yaounde. Three groups (I to III) of M. tuberculosis were identified among 93 isolates randomly selected. RAPD analysis provided a rapid and easy means of identifying polymorphism in M. tuberculosis isolates, and it was found to be a valuable alternative epidemiological tool. RAPD was used to select the new site of diagnostic by PCR. Also single nucleotide polymorphisms between M. tuberculosis and M. bovis were found, suggesting that RAPD can be a useful technique for distinguishing between species. Conclusions: Molecular typing is defined as the integration of conventional epidemiological approach to track specific strains of pathogens in order to understand the distribution of disease in populations.
Authors: Shakya T, Stogios PJ, Waglechner N, Evdokimova E, Ejim L, Blanchard JE, McArthur AG, Savchenko A, Wright GD
Chemistry & Biology 2011 Dec 23;18(12):1591-601
Kinase-mediated resistance to antibiotics is a significant clinical challenge. These enzymes share a common protein fold characteristic of Ser/Thr/Tyr protein kinases. We screened 14 antibiotic resistance kinases against 80 chemically diverse protein kinase inhibitors to map resistance kinase chemical space. The screens identified molecules with both broad and narrow inhibition profiles, proving that protein kinase inhibitors offer privileged chemical matter with the potential to block antibiotic resistance. One example is the flavonol quercetin, which inhibited a number of resistance kinases in vitro and in vivo. This activity was rationalized by determination of the crystal structure of the aminoglycoside kinase APH(2″)-IVa in complex with quercetin and its antibiotic substrate kanamycin. Our data demonstrate that protein kinase inhibitors offer chemical scaffolds that can block antibiotic resistance, providing leads for co-drug design.
Authors: Kirischian N, McArthur AG, Jesuthasan C, Krattenmacher B, Wilson JY.
J Mol Evol. 2011 Jan;72(1):56-71.
Cytochrome P450 (CYP) proteins compose a highly diverse superfamily found in all domains of life. These proteins are enzymes involved in metabolism of endogenous and exogenous compounds. In vertebrates, the CYP2 family is one of the largest, most diverse and plays an important role in mammalian drug metabolism. However, there are more than 20 vertebrate CYP2 subfamilies with uncertain evolution and fairly discrete subfamily composition within vertebrate classes, hindering extrapolation of knowledge across subfamilies. To better understand CYP2 diversity, a phylogenetic analysis of 196 CYP2 protein sequences from 16 species was performed using a maximum likelihood approach and Bayesian inference. The analyses included the CYP2 compliment from human, fugu, zebrafish, stickleback, medaka, cow, and dog genomes. Additional sequences were included from rabbit, marsupial, platypus, chicken, frog, and salmonid species. Three CYP2 sequences from the tunicate Ciona intestinalis were utilized as the outgroup. Results indicate a single ancestral vertebrate CYP2 gene and monophyly of all CYP2 subfamilies. Two subfamilies (CYP2R and CYP2U) pre-date vertebrate diversification, allowing direct comparison across vertebrate classes, while all other subfamilies originated during vertebrate diversification, often within specific vertebrate lineages. Analysis of site-specific evolution indicates that some substrate recognition sites (SRS) previously proposed for CYP genes do not have elevated rates of evolution, suggesting that these regions of the protein are not necessarily important in recognition of CYP2 substrates. Type II functional divergence analysis identified multiple residues in the active site of CYP2F, CYP2A, and CYP2B proteins that have undergone radical biochemical changes and may be functionally important.
Authors: Goldstone, J.V., A.G. McArthur, A. Kubota, J. Zanette, T. Parente, M. Jönsson, D.R. Nelson, & J.J. Stegeman
Increasing use of zebrafish in drug discovery and mechanistic toxicology demands knowledge of cytochrome P450 (CYP) gene regulation and function. CYP enzymes catalyze oxidative transformation leading to activation or inactivation of many endogenous and exogenous chemicals, with consequences for normal physiology and disease processes. Many CYPs potentially have roles in developmental specification, and many chemicals that cause developmental abnormalities are substrates for CYPs. Here we identify and annotate the full suite of CYP genes in zebrafish, compare these to the human CYP gene complement, and determine the expression of CYP genes during normal development. Zebrafish have a total of 94 CYP genes, distributed among 18 gene families found also in mammals. There are 32 genes in CYP families 5 to 51, most of which are direct orthologs of human CYPs that are involved in endogenous functions including synthesis or inactivation of regulatory molecules. The high degree of sequence similarity suggests conservation of enzyme activities for these CYPs, confirmed in reports for some steroidogenic enzymes (e.g. CYP19, aromatase; CYP11A, P450scc; CYP17, steroid 17a-hydroxylase), and the CYP26 retinoic acid hydroxylases. Complexity is much greater in gene families 1, 2, and 3, which include CYPs prominent in metabolism of drugs and pollutants, as well as of endogenous substrates. There are orthologous relationships for some CYP1 s and some CYP3 s between zebrafish and human. In contrast, zebrafish have 47 CYP2 genes, compared to 16 in human, with only two (CYP2R1 and CYP2U1) recognized as orthologous based on sequence. Analysis of shared synteny identified CYP2 gene clusters evolutionarily related to mammalian CYP2 s, as well as unique clusters. Transcript profiling by microarray and quantitative PCR revealed that the majority of zebrafish CYP genes are expressed in embryos, with waves of expression of different sets of genes over the course of development. Transcripts of some CYP occur also in oocytes. The results provide a foundation for the use of zebrafish as a model in toxicological, pharmacological and chemical disease research.
Authors: Birkeland SR, Preheim SP, Davids BJ, Cipriano MJ, Palm D, Reiner DS, Svärd SG, Gillin FD, McArthur AG.
Molecular and Biochemical Parasitology 2010, 174(1): 62-65.
We quantified mRNA abundance from 10 stages in the Giardia lamblia life cycle in vitro using Serial Analysis of Gene Expression (SAGE). 163 abundant transcripts were expressed constitutively. 71 transcripts were upregulated specifically during excystation and 42 during encystation. Nonetheless, the transcriptomes of cysts and trophozoites showed major differences. SAGE detected co-expressed clusters of 284 transcripts differentially expressed in cysts and excyzoites and 287 transcripts in vegetative trophozoites and encysting cells. All clusters included known genes and pathways as well as proteins unique to Giardia or diplomonads. SAGE analysis of the Giardia life cycle identified a number of kinases, phosphatases, and DNA replication proteins involved in excystation and encystation, which could be important for examining the roles of cell signaling in giardial differentiation. Overall, these data pave the way for directed gene discovery and a better understanding of the biology of G. lamblia.
Authors: Taft AS, Vermeire JJ, Bernier J, Birkeland SR, Cipriano MJ, Papa AR, McArthur AG, Yoshino TP.
Parasitology 2009, 136(5): 469-485.
Infection of the snail, Biomphalaria glabrata, by the free-swimming miracidial stage of the human blood fluke, Schistosoma mansoni, and its subsequent development to the parasitic sporocyst stage is critical to establishment of viable infections and continued human transmission. We performed a genome-wide expression analysis of the S. mansoni miracidia and developing sporocyst using Long Serial Analysis of Gene Expression (LongSAGE). Five cDNA libraries were constructed from miracidia and in vitro cultured 6- and 20-day-old sporocysts maintained in sporocyst medium (SM) or in SM conditioned by previous cultivation with cells of the B. glabrata embryonic (Bge) cell line. We generated 21440 SAGE tags and mapped 13381 to the S. mansoni gene predictions (v4.0e) either by estimating theoretical 3′ UTR lengths or using existing 3′ EST sequence data. Overall, 432 transcripts were found to be differentially expressed amongst all 5 libraries. In total, 172 tags were differentially expressed between miracidia and 6-day conditioned sporocysts and 152 were differentially expressed between miracidia and 6-day unconditioned sporocysts. In addition, 53 and 45 tags, respectively, were differentially expressed in 6-day and 20-day cultured sporocysts, due to the effects of exposure to Bge cell-conditioned medium.
Authors: Morrison HG, McArthur AG, Gillin FD, Aley SB, Adam RD, Olsen GJ, Best AA, Cande WZ, Chen F, Cipriano MJ, Davids BJ, Dawson SC, Elmendorf HG, Hehl AB, Holder ME, Huse SM, Kim UU, Lasek-Nesselquist E, Manning G, Nigam A, Nixon JE, Palm D, Passamaneck NE, Prabhu A, Reich CI, Reiner DS, Samuelson J, Svard SG, Sogin ML
Science. 2007 Sep 28;317(5846):1921-6.
The genome of the eukaryotic protist Giardia lamblia, an important human intestinal parasite, is compact in structure and content, contains few introns or mitochondrial relics, and has simplified machinery for DNA replication, transcription, RNA processing, and most metabolic pathways. Protein kinases comprise the single largest protein class and reflect Giardia‘s requirement for a complex signal transduction network for coordinating differentiation. Lateral gene transfer from bacterial and archaeal donors has shaped Giardia‘s genome, and previously unknown gene families, for example, cysteine- rich structural proteins, have been discovered. Unexpectedly, the genome shows little evidence of heterozygosity, supporting recent speculations that this organism is sexual. This genome sequence will not only be valuable for investigating the evolution of eukaryotes, but will also be applied to the search for new therapeutics for this parasite.