Yasuaki Hiromasa
Kansas State University
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Featured researches published by Yasuaki Hiromasa.
Progress in Nucleic Acid Research and Molecular Biology | 2001
Thomas E. Roche; Jason C. Baker; Xiaohua Yan; Yasuaki Hiromasa; Xiaoming Gong; Tao Peng; Jianchun Dong; Ali Turkan; Shane A. Kasten
The mammalian pyruvate dehydrogenase complex (PDC) plays central and strategic roles in the control of the use of glucose-linked substrates as sources of oxidative energy or as precursors in the biosynthesis of fatty acids. The activity of this mitochondrial complex is regulated by the continuous operation of competing pyruvate dehydrogenase kinase (PDK) and pyruvate dehydrogenase phosphatase (PDP) reactions. The resulting interconversion cycle determines the fraction of active (nonphosphorylated) pyruvate dehydrogenase (E1) component. Tissue-specific and metabolic state-specific control is achieved by the selective expression and distinct regulatory properties of at least four PDK isozymes and two PDP isozymes. The PDK isoforms are members of a family of serine kinases that are not structurally related to cytoplasmic Ser/Thr/Tyr kinases. The catalytic subunits of the PDP isoforms are Mg2+-dependent members of the phosphatase 2C family that has binuclear metal-binding sites within the active site. The dihydrolipoyl acetyltransferase (E2) and the dihydrolipoyl dehydrogenase-binding protein (E3BP) are multidomain proteins that form the oligomeric core of the complex. One or more of their three lipoyl domains (two in E2) selectively bind each PDK and PDP1. These adaptive interactions predominantly influence the catalytic efficiencies and effector control of these regulatory enzymes. When fatty acids are the preferred source of acetyl-CoA and NADH, feedback inactivation of PDC is accomplished by the activity of certain kinase isoforms being stimulated upon preferentially binding a lipoyl domain containing a reductively acetylated lipoyl group. PDC activity is increased in Ca2+-sensitive tissues by elevating PDP1 activity via the Ca2+-dependent binding of PDP1 to a lipoyl domain of E2. During starvation, the irrecoverable loss of glucose carbons is restricted by minimizing PDC activity due to high kinase activity that results from the overexpression of specific kinase isoforms. Overexpression of the same PDK isoforms deleteriously hinders glucose consumption in unregulated diabetes.
Cellular and Molecular Life Sciences | 2007
Thomas E. Roche; Yasuaki Hiromasa
Abstract.The fraction of pyruvate dehydrogenase complex (PDC) in the active form is reduced by the activities of dedicated PD kinase isozymes (PDK1, PDK2, PDK3 and PDK4). Via binding to the inner lipoyl domain (L2) of the dihydrolipoyl acetyltransferase (E2 60mer), PDK rapidly access their E2-bound PD substrate. The E2-enhanced activity of the widely distributed PDK2 is limited by dissociation of ADP from its C-terminal catalytic domain, and this is further slowed by pyruvate binding to the N-terminal regulatory (R) domain. Via the reverse of the PDC reaction, NADH and acetyl-CoA reductively acetylate lipoyl group of L2, which binds to the R domain and stimulates PDK2 activity by speeding up ADP dissociation. Activation of PDC by synthetic PDK inhibitors binding at the pyruvate or lipoyl binding sites decreased damage during heart ischemia and lowered blood glucose in insulin-resistant animals. PDC activation also triggers apoptosis in cancer cells that selectively convert glucose to lactate.
Molecular Microbiology | 2009
Vinai Chittezham Thomas; Yasuaki Hiromasa; Nathan Harms; Lance R. Thurlow; John M. Tomich; Lynn E. Hancock
Extracellular DNA (eDNA), a by‐product of cell lysis, was recently established as a critical structural component of the Enterococcus faecalis biofilm matrix. Here, we describe fratricide as the governing principle behind gelatinase (GelE)‐mediated cell death and eDNA release. GFP reporter assays confirmed that GBAP (gelatinase biosynthesis‐activating pheromone) quorum non‐responders (GelE–SprE–) were a minority subpopulation of prey cells susceptible to the targeted fratricidal action of the quorum responsive predatorial majority (GelE+SprE+). The killing action is dependent on GelE, and the GelE producer population is protected from self‐destruction by the co‐production of SprE as an immunity protein. Targeted gene inactivation and protein interaction studies demonstrate that extracellular proteases execute their characteristic effects following downstream interactions with the primary autolysin, AtlA. Finally, we address a mechanism by which GelE and SprE may modify the cell wall affinity of proteolytically processed AtlA resulting in either a pro‐ or anti‐lytic outcome.
Journal of Proteome Research | 2009
Kaley Morris; Marcé D. Lorenzen; Yasuaki Hiromasa; John M. Tomich; Cris Oppert; Elena N. Elpidina; Konstantin Vinokurov; Juan Luis Jurat-Fuentes; Jeff Fabrick; Brenda Oppert
Tribolium castaneum is an important agricultural pest and an advanced genetic model for coleopteran insects. We have taken advantage of the recently acquired T. castaneum genome to identify T. castaneum genes and proteins in one of the more critical environmental interfaces of the insect, the larval alimentary tract. Genetic transcripts isolated from the T. castaneum larval gut were labeled and hybridized to a custom array containing oligonucleotides from predicted genes in the T. castaneum genome. Through a ranking procedure based on relative labeling intensity, we found that approximately 17.6% of the genes represented in the array were predicted to be highly expressed in gut tissue. Several genes were selected to compare relative expression levels in larval gut, head, or carcass tissues using quantitative real-time PCR, and expression levels were, with few exceptions, consistent with the gut rankings. In parallel with the microarrays, proteins extracted from the T. castaneum larval gut were subjected to proteomic analysis. Two-dimensional electrophoretic analysis combined with MALDI-TOF resulted in the identification of 37 of 88 selected protein samples. As an alternative strategy, one-dimensional electrophoretic separation of T. castaneum larval gut proteins followed by two-dimensional nano-HPLC and ESI-MS/MS resulted in the identification of 98 proteins. A comparison of the proteomic studies indicated that 16 proteins were commonly identified in both, whereas 80 proteins from the proteomic analyses corresponded to genes with gut rankings indicative of high expression in the microarray analysis. These data serve as a resource of T. castaneum transcripts and proteins in the larval gut and provide the basis for comparative transcriptomic and proteomic studies related to the gut of coleopteran insects.
PLOS ONE | 2012
Sushanth Gudlur; Pinakin Sukthankar; Jian Gao; L. Adriana Avila; Yasuaki Hiromasa; Jianhan Chen; Takeo Iwamoto; John M. Tomich
Peptide-based packaging systems show great potential as safer drug delivery systems. They overcome problems associated with lipid-based or viral delivery systems, vis-a-vis stability, specificity, inflammation, antigenicity, and tune-ability. Here, we describe a set of 15 & 23-residue branched, amphiphilic peptides that mimic phosphoglycerides in molecular architecture. These peptides undergo supramolecular self-assembly and form solvent-filled, bilayer delimited spheres with 50–200 nm diameters as confirmed by TEM, STEM and DLS. Whereas weak hydrophobic forces drive and sustain lipid bilayer assemblies, these all-peptide structures are stabilized potentially by both hydrophobic interactions and hydrogen bonds and remain intact at low micromolar concentrations and higher temperatures. A linear peptide lacking the branch point showed no self-assembly properties. We have observed that these peptide vesicles can trap fluorescent dye molecules within their interior and are taken up by N/N 1003A rabbit lens epithelial cells grown in culture. These assemblies are thus potential drug delivery systems that can overcome some of the key limitations of the current packaging systems.
Journal of Proteome Research | 2012
Neal T. Dittmer; Yasuaki Hiromasa; John M. Tomich; Nanyan Lu; Richard W. Beeman; Karl J. Kramer; Michael R. Kanost
The insect cuticle is a composite biomaterial made up primarily of chitin and proteins. The physical properties of the cuticle can vary greatly from hard and rigid to soft and flexible. Understanding how different cuticle types are assembled can aid in the development of novel biomimetic materials for use in medicine and technology. Toward this goal, we have taken a combined proteomics and transcriptomics approach with the red flour beetle, Tribolium castaneum, to examine the protein and gene expression profiles of the elytra and hindwings, appendages that contain rigid and soft cuticles, respectively. Two-dimensional gel electrophoresis analysis revealed distinct differences in the protein profiles between elytra and hindwings, with four highly abundant proteins dominating the elytral cuticle extract. MALDI/TOF mass spectrometry identified 19 proteins homologous to known or hypothesized cuticular proteins (CPs), including a novel low complexity protein enriched in charged residues. Microarray analysis identified 372 genes with a 10-fold or greater difference in transcript levels between elytra and hindwings. CP genes with higher expression in the elytra belonged to the Rebers and Riddiford family (CPR) type 2, or cuticular proteins of low complexity (CPLC) enriched in glycine or proline. In contrast, a majority of the CP genes with higher expression in hindwings were classified as CPR type 1, cuticular proteins analogous to peritrophins (CPAP), or members of the Tweedle family. This research shows that the elyra and hindwings, representatives of rigid and soft cuticles, have different protein and gene expression profiles for structural proteins that may influence the mechanical properties of these cuticles.
PLOS ONE | 2009
Jeremy L. Marshall; Diana L. Huestis; Yasuaki Hiromasa; Shanda Wheeler; Cris Oppert; Susan A. Marshall; John M. Tomich; Brenda Oppert
Postmating, prezygotic phenotypes, especially those that underlie reproductive isolation between closely related species, have been a central focus of evolutionary biologists over the past two decades. Such phenotypes are thought to evolve rapidly and be nearly ubiquitous among sexually reproducing eukaryotes where females mate with multiple partners. Because these phenotypes represent interplay between the male ejaculate and female reproductive tract, they are fertile ground for reproductive senescence – as ejaculate composition and female physiology typically change over an individuals life span. Although these phenotypes and their resulting dynamics are important, we have little understanding of the proteins that mediate these phenotypes, particularly for species groups where postmating, prezygotic traits are the primary mechanism of reproductive isolation. Here, we utilize proteomics, RNAi, mating experiments, and the Allonemobius socius complex of crickets, whose members are primarily isolated from one another by postmating, prezygotic phenotypes (including the ability of a male to induce a female to lay eggs), to demonstrate that one of the most abundant ejaculate proteins (a male accessory gland-biased protein similar to a trypsin-like serine protease) decreases in abundance over a males reproductive lifetime and mediates the induction of egg-laying in females. These findings represent one of the first studies to identify a protein that plays a role in mediating both a postmating, prezygotic isolation pathway and reproductive senescence.
PLOS Genetics | 2012
Yasuyuki Arakane; Joseph Lomakin; Stevin H. Gehrke; Yasuaki Hiromasa; John M. Tomich; Subbaratnam Muthukrishnan; Richard W. Beeman; Karl J. Kramer; Michael R. Kanost
Insect cuticle is composed primarily of chitin and structural proteins. To study the function of structural cuticular proteins, we focused on the proteins present in elytra (modified forewings that become highly sclerotized and pigmented covers for the hindwings) of the red flour beetle, Tribolium castaneum. We identified two highly abundant proteins, TcCPR27 (10 kDa) and TcCPR18 (20 kDa), which are also present in pronotum and ventral abdominal cuticles. Both are members of the Rebers and Riddiford family of cuticular proteins and contain RR2 motifs. Transcripts for both genes dramatically increase in abundance at the pharate adult stage and then decline quickly thereafter. Injection of specific double-stranded RNAs for each gene into penultimate or last instar larvae had no effect on larval–larval, larval–pupal, or pupal–adult molting. The elytra of the resulting adults, however, were shorter, wrinkled, warped, fenestrated, and less rigid than those from control insects. TcCPR27-deficient insects could not fold their hindwings properly and died prematurely approximately one week after eclosion, probably because of dehydration. TcCPR18-deficient insects exhibited a similar but less dramatic phenotype. Immunolocalization studies confirmed the presence of TcCPR27 in the elytral cuticle. These results demonstrate that TcCPR27 and TcCPR18 are major structural proteins in the rigid elytral, dorsal thoracic, and ventral abdominal cuticles of the red flour beetle, and that both proteins are required for morphogenesis of the beetles elytra.
Molecular Biology and Evolution | 2011
Jeremy L. Marshall; Diana L. Huestis; Christopher Garcia; Yasuaki Hiromasa; Shanda Wheeler; Suegene Noh; John M. Tomich; Daniel J. Howard
Two of the most well-supported patterns to have emerged over the past two decades of research in evolutionary biology are the occurrence of divergent natural selection acting on many male and female reproductive tract proteins and the importance of postmating, prezygotic phenotypes in reproductively isolating closely related species. Although these patterns appear to be common across a wide variety of taxa, the link between them remains poorly documented. Here, we utilize comparative proteomic techniques to determine whether or not there is evidence for natural selection acting on the ejaculate proteomes of two cricket species (Allonemobius fasciatus and A. socius) which are reproductively isolated primarily by postmating, prezygotic phenotypes. In addressing this question, we compare the degree of within-species polymorphism and between-species divergence between the ejaculate and thorax proteomes of these two species. We found that the ejaculate proteomes are both less polymorphic and more divergent than the thorax proteomes. Additionally, we assessed patterns of nucleotide variation for two species-specific ejaculate proteins and found evidence for both reduced levels of variation within species and positive selection driving divergence between species. In contrast, non-species-specific proteins exhibited higher levels of within-species nucleotide variation and no signatures of positive selection. Nucleotide and putative functional data for the two species-specific proteins, along with data for a third protein (ejaculate serine protease), suggest that all three of these genes are candidate speciation genes in need of further study. Overall, these patterns of proteome and nucleotide divergence provide support for the hypothesis that there is a causative link between selection-driven divergence of male ejaculate proteins and the evolution of postmating, prezygotic barriers to gene flow within Allonemobius.
Structure | 2008
Xuekui Yu; Yasuaki Hiromasa; Hua Tsen; James K. Stoops; Thomas E. Roche; Z. Hong Zhou
Dihydrolipoyl acetyltransferase (E2) is the central component of pyruvate dehydrogenase complex (PDC), which converts pyruvate to acetyl-CoA. Structural comparison by cryo-electron microscopy (cryo-EM) of the human full-length and truncated E2 (tE2) cores revealed flexible linkers emanating from the edges of trimers of the internal catalytic domains. Using the secondary structure constraints revealed in our 8 A cryo-EM reconstruction and the prokaryotic tE2 atomic structure as a template, we derived a pseudo atomic model of human tE2. The active sites are conserved between prokaryotic tE2 and human tE2. However, marked structural differences are apparent in the hairpin domain and in the N-terminal helix connected to the flexible linker. These permutations away from the catalytic center likely impart structures needed to integrate a second component into the inner core and provide a sturdy base for the linker that holds the pyruvate dehydrogenase for access by the E2-bound regulatory kinase/phosphatase components in humans.