Life Sciences Commons^™

Structure Of The Protein Kinase Cβ Phospholipid-Binding C2 Domain Complexed With Ca2+, R. Bryan Sutton, Stephen R. Sprang

Biological Sciences Faculty Publications

Background: Conventional isoforms (α, β and γ) of protein kinase C (PKC) are synergistically activated by phosphatidylserine and Ca²⁺; both bind to C2 domains located within the PKC amino-terminal regulatory regions. C2 domains contain a bipartite or tripartite Ca²⁺-binding site formed by opposing loops at one end of the protein. Neither the structural basis for cooperativity between phosphatidylserine and Ca²⁺, nor the binding site for phosphatidylserine are known. Results: The structure of the C2 domain from PKCβ complexed with Ca²⁺ and o-phospho-L-serine has been determined to 2.7 Å resolution using X-ray crystallography. The …

Mutations In Bartonella Bacilliformis Gyrb Confer Resistance To Coumermycin A(1), James M. Battisti, Laura A. Smitherman, D. Scott Samuels, Michael F. Minnick

Biological Sciences Faculty Publications

This study describes the first isolation and characterization of spontaneous mutants conferring natural resistance to an antibiotic for any Bartonella species. The Bartonella bacilliformis gyrB gene, which encodes the B subunit of DNA gyrase, was cloned and sequenced. The gyrB open reading frame (ORF) is 2,079 bp and encodes a deduced amino acid sequence of 692 residues, corresponding to a predicted protein of similar to 77.5 kDa. Sequence alignment indicates that B. bacilliformis GyrB is most similar to the GyrB protein from Bacillus subtilis (40.1% amino acid sequence identity) and that it contains the longest N-terminal tail (52 residues) of …

Invasion Of The Nucleotide Snatchers, Stephen R. Sprang, David E. Coleman

Biological Sciences Faculty Publications

Although the mechanics differ, GEFs appear to deform their substrates in similar ways. In all cases, switch I is pulled away from switch II and the P loop, exposing the active site; dislocation of switch I also displaces a Mg²⁺-binding residue, but this in itself should have little affect on GDP affinity. GEFs also restructure and displace the amino terminus of switch II and consequently dismantle the χ-phosphate-binding site, at the same time moving a conserved aspartate residue that serves as a water-mediated Mg²⁺ ligand. Residues, either from the GEF or the G protein, are positioned to …

Identification Of A G(Iα) Binding Site On Type V Adenylyl Cyclase, Carmen W. Dessauer, John J.G. Tesmer, Stephen R. Sprang, Alfred G. Gilman

Biological Sciences Faculty Publications

The stimulatory G protein α subunit G(sα) binds within a cleft in adenylyl cyclase formed by the α1-α2 and α3-β4 loops of the C₂ domain. The pseudosymmetry of the C₁ and C₂ domains of adenylyl cyclase suggests that the homologous inhibitory α subunit G(iα) could bind to the analogous cleft within C₁. We demonstrate that myristoylated guanosine 5'-3-O- (thio)triphosphate-G(iα1) forms a stable complex with the C₁ (but not the C₂) domain of type V adenylyl cyclase. Mutagenesis of the membrane-bound enzyme identified residues whose alteration either increased or substantially decreased the IC …

Asymmetrical Force Production In The Maneuvering Flight Of Pigeons, Douglas R. Warrick, Kenneth P. Dial, Andrew A. Biewener

Biological Sciences Faculty Publications

Downstroke force produced by Rock Doves (Columba livia) as they negotiated an obstacle course was measured using in vivo recordings of delto-pectoral crest strain. During this slow $(<6\ {\rm m}\ {\rm s}^{-1})$ , maneuvering flight, pigeons produced a series of four to six successive wingbeats in which the wing on the outside of the turn produced greater peak force than the wing on the inside of the turn, suggesting that the birds maneuvered in a saltatory manner during slow flight. This asymmetrical downstroke force may be used to increase or reestablish bank lost during upstroke, or it may be directed as thrust to compensate for adverse yaw or create excess yaw to alter the bird's direction of flight. Continuous production of asymmetrical downstroke force through a turn differs from the traditional model of maneuvering flight, in which asymmetrical force is used only to initiate a bank, the forces are briefly reversed to arrest the momentum of the roll and then equalized to maintain the established bank, and the redirected lift of the wings then effects a turn. Although this traditional model probably describes most turns initiated during fast and gliding flight in birds, it underestimates the complexity of maneuvering during slow, flapping flight, where sophisticated kinematics and neuromuscular control are needed to change direction effectively.

Increased Photosynthesis Offsets Costs Of Allocation To Sapwood In An Arid Environment, Eileen V. Carey, Ragan M. Callaway, Evan H. Delucia

Biological Sciences Faculty Publications

We assessed the effect that varying patterns of biomass allocation had on growth of ponderosa pine (Pinus ponderosa) growing in the desert climate of the Great Basin and the montane climate of the eastern Sierra Nevada. Prior work established that desert trees have lower leaf:sapwood area ratios than montane trees (0.104 and 0.201 m²/cm², respectively) and proportionally greater stem respiration. Sapwood:leaf mass ratios are also greater and increase more as a function stem diameter in desert than in montane trees. We hypothesized that this increased allocation of carbon to stem sapwood and stem respiration …

Grizzly Bear Digging: Effects On Subalpine Meadow Plants In Relation To Mineral Nitrogen Availability, Sandra E. Tardiff, Jack Arthur Stanford

Biological Sciences Faculty Publications

Grizzly bears (Ursus arctos horribilis) affect plant distributions and mineral nitrogen availability when they forage by digging for the bulbs of glacier lilies (Erythronium grandiflorum) growing in subalpine meadows of Glacier National Park, Montana, United States. Our working hypothesis is that grizzly bears structure plant communities and influence nitrogen availability when they selectively dig for preferred plants. In this paper, we report on differences found in recently disturbed digs (<5 yr old) when compared to adjacent, undisturbed meadow.

We used ion exchange resin bags to determine the availability of mineral nitrogen in grizzly bear digs compared to undisturbed meadow. Soil in digs contained significantly …

Effective Recovery Of Bacterial Dna And Percent-Guanine-Plus-Cytosine-Based Analysis Of Community Structure In The Gastrointestinal Tract Of Broiler Chickens, Juha H. A. Apajalahti, Laura K. Särkilahti, Brita R. E. Mäki, J. Pekka Heikkinen, Päivi H. Nurminen, William E. Holben

Biological Sciences Faculty Publications

A DNA-based, direct method for initial characterization of the total bacterial community in ileum and cecum of the chicken gastrointestinal (GI) tract was developed. The efficiencies of bacterial extraction and lysis were >95 and >99%, respectively, and therefore the DNA recovered should accurately reflect the bacterial communities of the ileal and cecal digesta. Total bacterial DNA samples were fractionated according to their percent G+C content. The profiles reflecting the composition of the bacterial community were reproducible within each compartment, but different between the compartments of the GI tract. This approach is independent of the culturability of the bacteria in the …

On The Importance Of Stopover Sites To Migrating Birds, Richard L. Hutto

Biological Sciences Faculty Publications

No abstract provided.

Structural Basis Of Activity And Subunit Recognition In G Protein Heterotrimers, Mark A. Wall, Bruce A. Posner, Stephen R. Sprang

Biological Sciences Faculty Publications

Background: Inactive heterotrimeric G proteins are composed of a GDP-bound α subunit (G(α)) and a stable heterodimer of G(β) and G(γ) subunits. Upon stimulation by a receptor, G(α) subunits exchange GDP for GTP and dissociate from G(βγ) both G(α) and G(βγ) then interact with downstream effectors. Isoforms of G(α), G(β) and G(γ) potentially give rise to many heterotrimeric combinations, limited in part by amino acid sequence differences that lead to selective interactions. The mechanism by which GTP promotes G(βγ) dissociation is incompletely understood. The Gly203→Ala mutant of G(iα1) binds and hydrolyzes GTP normally but does not dissociate from G(βγ) demonstrating …

Continued Utilization Of Ccr5 Coreceptor By A Newly Derived T-Cell Line-Adapted Isolate Of Human Immunodeficiency Virus Type 1, Kathryn E. Follis, Meg Trahey, Rachel A. Lacasse, Jack H. Nunberg

Biological Sciences Faculty Publications

The differential use of CC chemokine receptor 5 (CCR5) and CXC chemokine receptor 4 (CXCR4) may be intimately involved in the transmission and progression of human immunodeficiency virus infection. Changes in coreceptor utilization have also been noted upon adaptation of primary isolates (PI) to growth in established T-cell lines. All of the T-cell line-adapted (TCLA) viruses studied to date utilize CXCR4 but not CCR5. This observation had been suggested as an explanation for the sensitivity of TCLA, but not PI, viruses to neutralization by recombinant gp120 antisera and V3-directed monoclonal antibodies, but recent studies have shown coreceptor utilization to be …

Bowen Ratio Estimates Of Evapotranspiration For Tamarix Ramosissima Stands On The Virgin River In Southern Nevada, D. A. Devitt, Anna Sala, S. D. Smith, J. Cleverly, L. K. Shaulis, R. Hammett

Biological Sciences Faculty Publications

A Bowen ratio energy balance was conducted over a Tamarix ramosissima (saltcedar) stand growing in a riparian corridor along the Virgin River in southern Nevada, Measurements in two separate years were compared and contrasted on the basis of changes in growing conditions. In 1994, a drought year, record high temperatures, dry winds, and a falling water table caused partial wilt of outer smaller twigs in the canopy of many trees in the stand around the Bowen tower. Subsequently, evapotranspiration (ET) estimates declined dramatically over a 60-day period (11 mm d(-1) to <1 mm d(-1)). In 1995, the Virgin River at the Bowen tower area changed its course, hydrologically isolating the Tamarix stand in the vicinity of the tower. In 1996, a 25% canopy loss was visually estimated for the Tamarix growing in the area of the tower. Higher soil temperatures relative to air temperatures were recorded in 1996 in response to this loss in canopy, With a more open canopy, thermally induced turbulence was observed in 1996, On day 160 of 1996, a 28 degrees C rise over a 9-hour period was correlated with increased wind speeds of greater than 4 m s(-1). Subsequently, higher ET estimates were made in 1996 compared to 1994 (145 cm versus 75 cm), However, the energy balance was dominated by advection in 1996, with latent energy flux exceeding net radiation 65% of the measurement days compared to only 11% in 1994, We believe this advection was on a scale of the floodplain (hundreds of meters) as opposed to regional advection, since the majority of wind (90%) was in a N-S direction along the course of the river, and that a more open canopy allowed the horizontal transfer of energy into the Tamarix stand at the Bowen tower. Our results suggest that Tamarix has the potential to be both a low water user and a high water user, depending on moisture availability, canopy development, and atmospheric demand, and that advection can dominate energy balances and ET in aridland riparian zones such as the Virgin River.

The A326s Mutant Of G(Iα1) As An Approximation Of The Receptor-Bound State, Bruce A. Posner, Mark B. Mixon, Mark A. Wall, Stephen R. Sprang, Alfred G. Gilman

Biological Sciences Faculty Publications

Agonist-bound heptahelical receptors activate heterotrimeric G proteins by catalyzing exchange of GDP for GTP on their α subunits. In search of an approximation of the receptor-α subunit complex, we have considered the properties of A326S G(iα1), a mutation discovered originally in G(sα) (Iiri, T., Herzmark, P., Nakamoto, J. M., Van Dop, C., and Bourne, H. R. (1994) Nature 371, 164-168) that mimics the effect of receptor on nucleotide exchange. The mutation accelerates dissociation of GDP from the α(i1)β₁γ₂ heterotrimer by 250-fold. Nevertheless, affinity of mutant G(iα1) for GTPγS is high in the presence of Mg²⁺, …

Multiple Duplications Of Yeast Hexose Transport Genes In Response To Selection In A Glucose-Limited Environment, Celeste J. Brown, Kristy M. Todd, R. Frank Rosenzweig

Biological Sciences Faculty Publications

When microbes evolve in a nutrient-limited environment, natural selection can be predicted to favor genetic changes that give cells greater access to limiting substrate. We analyzed a population of baker's yeast that underwent 450 generations of glucose-limited growth. Relative to the strain used as the inoculum, the predominant cell type at the end of this experiment sustains growth at significantly lower steady-state glucose concentrations and demonstrates markedly enhanced cell yield per mole glucose, significantly enhanced high-affinity glucose transport, and greater relative fitness in pairwise competition. These changes are correlated with increased levels of mRNA hybridizing to probe generated from the …

Molecular Analysis Of Bacterial Communities In A Three-Compartment Granular Activated Sludge System Indicates Community-Level Control By Incompatible Nitrification Processes, William Holben, Kazuhiko Noto, Tatsuo Sumino, Yuichi Suwa

Biological Sciences Faculty Publications

Bacterial community structure and the predominant nitrifying activities and populations in each compartment of a three-compartment activated sludge system were determined, Each compartment was originally inoculated with the same activated sludge community entrapped in polyethylene glycol gel granules, and ammonium nitrogen was supplied to the system in an inorganic salts solution at a rate of 5.0 g of N liter of granular activated sludge(-1) day(-1). After 150 days of operation, the system was found to comprise a series of sequential nitrifying reactions (K, Note, T. Ogasawara, Y, Suwa, and T. Sumino, Water Res. 32:769-773, 1998), presumably mediated by different bacterial …

Exchange Of Substrate And Inhibitor Specificities Between Adenylyl And Guanylyl Cyclases, R. K. Sunahara, A. Beuve, J. J.G. Tesmer, S. R. Sprang, D. L. Garbers, A. G. Gilman

Biological Sciences Faculty Publications

The active sites of guanylyl and adenylyl cyclases are closely related. The crystal structure of adenylyl cyclase and modeling studies suggest that specificity for ATP or GTP is dictated in part by a few amino acid residues, invariant in each family, that interact with the purine ring of the substrate. By exchanging these residues between guanylyl cyclase and adenylyl cyclase, we can completely change the nucleotide specificity of guanylyl cyclase and convert adenylyl cyclase into a nonselective purine nucleotide cyclase. The activities of these mutant enzymes remain fully responsive to their respective stimulators, sodium nitroprusside and G(s)α. The specificity of …

Insect Herbivory Above- And Belowground: Individual And Joint Effects On Plant Fitness, John L. Maron

Biological Sciences Faculty Publications

Understanding of the selective effects of insect herbivory on plants comes primarily from studies of herbivory aboveground. The impact of belowground herbivory, either in isolation or in concert with herbivory aboveground, on plant fitness is only beginning to be understood.

I reduced the densities of root-boring ghost moth (Hepialus californicus) larvae and/or flower- and seed-feeding insects of bush lupine (Lupinus arboreus), a woody shrub, and followed fecundity and survival of plants for three years. In year one, suppression of aboveground herbivores increased mean seed output by 31%, but suppression of belowground herbivores had no significant effect …

Coreceptor Utilization By Human Immunodeficiency Virus Type 1 Is Not A Primary Determinant Of Neutralization Sensitivity, Rachel A. Lacasse, Kathryn E. Follis, Tarsem Moudgil, Meg Trahey, James M. Binley, Vicente Planelles, Susan Zolla-Pazner, Jack H. Nunberg

Biological Sciences Faculty Publications

We have examined the relationship between coreceptor utilization and sensitivity to neutralization in a primary isolate of human immunodeficiency virus type I and its T-cell line-adapted (TCLA) derivative. We determined that adaptation of the primary-isolate (PI) virus 168P results in the loss of the unique capacity of PI viruses to utilize the CCR5 coreceptor and in the acquisition by the TCLA 168C virus of sensitivity to neutralization by V3-directed monoclonal antibodies (MAbs). In experiments wherein infection by 168P is directed via either the CCR5 or the CXCR4 pathway, we demonstrate that the virus, as well as pseudotyped virions bearing a …

Population Genetics And Pattern Of Larval Dispersal Of The Endemic Hawaiian Freshwater Amphidromous Gastropod Neritina Granosa (Prosobranchia: Neritidae), Marc H. Hodges, Fred W. Allendorf

Biological Sciences Faculty Publications

Protein electrophoresis was used to study the population genetics of the endemic Hawaiian freshwater amphidromous gastropod Neritina granosa Sowerby. The genetic information was used to infer the pattern and degree of planktonic larval dispersal. Samples were taken from 12 streams located throughout the Hawaiian Archipelago during July, August, and September 1991. Overall mean heterozygosity was 0.052. Heterozygote deficiency was comparable with that found in other mollusks and marine invertebrates. Gene flow was substantial and was generally sufficient to maintain similar allele frequencies among stream populations. An island model of migration was indicated. However, significant heterogeneity among populations was observed and …