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Crystal Structure Of The Adenylyl Cyclase Activator G(Sα), Roger K. Sunahara, John J.G. Tesmer, Alfred G. Gilman, Stephen R. Sprang
Crystal Structure Of The Adenylyl Cyclase Activator G(Sα), Roger K. Sunahara, John J.G. Tesmer, Alfred G. Gilman, Stephen R. Sprang
Biological Sciences Faculty Publications
The crystal structure of G(sα), the heterotrimeric G protein α subunit that stimulates adenylyl cyclase, was determined at 2.5 Å in a complex with guanosine 5'-O-(3-thio-triphosphate) (GTPγS). G(sα) is the prototypic member of a of GTP-binding proteins that regulate the activities of effectors in a hormone-dependent manner. Comparison of the structure of G(sα)·GTPγS with that of G(iα)·GTPγS suggest that their effector specificity is primarily dictated by the shape of the binding surface formed by the switch II helix and the α3-β5 loop, despite the high sequence homology of these elements. In contrast, sequence divergence explains the inability of regulators of …
Crystal Structure Of The Catalytic Domains Of Adenylyl Cyclase In A Complex With G(Sα)·Gtpγς, John J.G. Tesmer, Roger K. Sunahara, Alfred G. Gilman, Stephen R. Sprang
Crystal Structure Of The Catalytic Domains Of Adenylyl Cyclase In A Complex With G(Sα)·Gtpγς, John J.G. Tesmer, Roger K. Sunahara, Alfred G. Gilman, Stephen R. Sprang
Biological Sciences Faculty Publications
The crystal structure of a soluble, catalytically active form of adenylyl cyclase in a complex with its stimulatory heterotrimeric G protein α subunit (G(sα)) and forskolin was determined to a resolution of 2.3 angstroms. When P-site inhibitors were soaked into native crystals of the complex, the active site of adenylyl cyclase was located and structural elements important for substrate recognition and catalysis were identified. On the basis of these and other structures, a molecular mechanism is proposed for the activation of adenylyl cyclase by G(sα).
Ecophysiological Responses Of Three Riparian Graminoids To Changes In The Soil Water Table, Anna Sala, Robert S. Nowak
Ecophysiological Responses Of Three Riparian Graminoids To Changes In The Soil Water Table, Anna Sala, Robert S. Nowak
Biological Sciences Faculty Publications
We examined the effect of changes in soil water table on the water relations, leaf gas exchange, and aboveground biomass of three riparian graminoids native to the semiarid western United States: Carex lanuginosa, Juncus balticus, and Carex nebrascensis. All three species co-occur at the wettest microhabitats within riparian corridors, but J. balticus and C. nebrascensis extend into drier areas. Lowering the water table to 1 m had little effect on the leaf gas exchange characteristics of the three graminoids. In the greenhouse, experimental reductions of the water table when plants had three fully mature leaves did not affect gas exchange …
Consumption Of Atmospheric Isoprene In Soil, Cory C. Cleveland, Joseph B. Yavitt
Consumption Of Atmospheric Isoprene In Soil, Cory C. Cleveland, Joseph B. Yavitt
Ecosystem and Conservation Sciences Faculty Publications
Natural vegetation annually emits 503 Tg yr−1 of isoprene (2-methyl-1,3 butadiene) to the global atmosphere where it reacts very rapidly with hydroxyl radicals and strongly regulates atmospheric chemistry. Current models of the compound's chemical behavior assume the atmosphere is the only significant sink; however, there is evidence that soil may consume isoprene. Here we show through field and laboratory studies that soil exposed to isoprene at low mixing ratios removed isoprene to concentrations below those commonly observed in forest canopies, and that the removal of isoprene was biologically mediated. On the basis of laboratory studies with soil from several …
Competition And Facilitation: A Synthetic Approach To Interactions In Plant Communities, Ragan M. Callaway, Lawrence R. Walker
Competition And Facilitation: A Synthetic Approach To Interactions In Plant Communities, Ragan M. Callaway, Lawrence R. Walker
Biological Sciences Faculty Publications
Interactions among organisms take place within a complex milieu of abiotic and biotic processes, but we generally study them as solitary phenomena. Complex combinations of negative and positive interactions have been identified in a number of plant communities. The importance of these two processes in structuring plant communities can best be understood by comparing them along gradients of abiotic stress, consumer pressure, and among different life stages, sizes, and densities of the interacting species. Here, we discuss the roles of life stage, physiology, indirect interactions, and the physical environment on the balance of competition and facilitation in plant communities.
Emissions From Smoldering Combustion Of Biomass Measured By Open-Path Fourier Transform Infrared Spectroscopy, Robert J. Yokelson, Ronald A. Susott, Darold E. Ward, James J. Reardon, David W. T. Griffith
Emissions From Smoldering Combustion Of Biomass Measured By Open-Path Fourier Transform Infrared Spectroscopy, Robert J. Yokelson, Ronald A. Susott, Darold E. Ward, James J. Reardon, David W. T. Griffith
Chemistry and Biochemistry Faculty Publications
Biomass samples from a diverse range of ecosystems were burned in the Intermountain Fire Sciences Laboratory open combustion facility. Midinfrared spectra of the nascent emissions were acquired at several heights above the fires with a Fourier transform infrared spectrometer (FTIR) coupled to an open multipass cell. In this report, the results from smoldering combustion during 24 fires are presented including production of carbon dioxide, carbon monoxide, methane, ethene, ethyne, propene, formaldehyde, 2-hydroxyethanal, methanol, phenol, acetic acid, formic acid, ammonia, hydrogen cyanide, and carbonyl sulfide. These were the dominant products observed, and many have significant influence on atmospheric chemistry at the …
Influence Of Alternate Host Densities On Brown-Headed Cowbird Parasitism Rates In Black-Capped Vireos, D. R. Barber, Thomas E. Martin
Influence Of Alternate Host Densities On Brown-Headed Cowbird Parasitism Rates In Black-Capped Vireos, D. R. Barber, Thomas E. Martin
Wildlife Biology Faculty Publications
Brown-headed Cowbird (Molothrus ater) parasitism is thought to be partly influenced by density of the host species, although tests of host density are relatively rare. We examined parasitism rates relative to the density of individual host species and densities of coexisting host species. We monitored 392 nests among coexisting host species and measured their densities among six habitats on Fort Hood Military Reservation, Texas during 1991-1992 to test the hypothesis that coexisting species affect parasitism rates in the endangered Black-capped Vireo (Vireo atricapillus). Black-capped Vireos and White-eyed Vireos (V. griseus) suffered three to four times higher cowbird parasitism than Northern …
Characterization Of The Sediment Bacterial Community In Groundwater Discharge Zones Of An Alkaline Fen: A Seasonal Study, Timothy C. Gsell, William E. Holben, Roy M. Ventullo
Characterization Of The Sediment Bacterial Community In Groundwater Discharge Zones Of An Alkaline Fen: A Seasonal Study, Timothy C. Gsell, William E. Holben, Roy M. Ventullo
Biological Sciences Faculty Publications
The cell density, activity, and community structure of the bacterial community in wetland sediments were monitored over a 13-month period. The study was performed at Cedar Bog, an alkaline fen. The objective was to characterize the relationship between the sediment bacterial community in groundwater upwelling zones and the physical and chemical factors which might influence the community structure and activity. DNA, protein, and lipid synthesis were measured at three different upwelling zones by using [H-3]thymidine, [C-14]leucine, and [C-14]glucose incorporation, respectively. The physiological status (apparent stress) of the consortium was assessed by comparing [C-14]glucose incorporation into membrane and that into storage …
Structure Of Rgs4 Bound To Alf4--Activated G(Iα1): Stabilization Of The Transition State For Gtp Hydrolysis, John J.G. Tesmer, David M. Berman, Alfred G. Gilman, Stephen R. Sprang
Structure Of Rgs4 Bound To Alf4--Activated G(Iα1): Stabilization Of The Transition State For Gtp Hydrolysis, John J.G. Tesmer, David M. Berman, Alfred G. Gilman, Stephen R. Sprang
Biological Sciences Faculty Publications
RGS proteins are GTPase activators for heterotrimeric G proteins. We report here the 2.8 Å resolution crystal structure of the RGS protein RGS4 complexed with G(iα1)-Mg2+-GDP-AlF4. Only the core domain of RGS4 is visible in the crystal. The core domain binds to the three switch regions of G(iα1), but does not contribute catalytic residues that directly interact with either GDP or AlF4. Therefore, RGS4 appears to catalyze rapid hydrolysis of GTP primarily by stabilizing the switch regions of G(iα1), although the conserved Asn-128 from RGS4 could also play a catalytic role by interacting with …
A Carboxy-Terminal Processing Protease Gene Is Located Immediately Upstream Of The Invasion-Associated Locus From Bartonella Bacilliformis, Samuel J. Mitchell, Michael F. Minnick
A Carboxy-Terminal Processing Protease Gene Is Located Immediately Upstream Of The Invasion-Associated Locus From Bartonella Bacilliformis, Samuel J. Mitchell, Michael F. Minnick
Biological Sciences Faculty Publications
A gene with homology to those encoding an unusual class of C-terminal processing proteases that flanks the invasion-associated locus ialAB of Bartonella bacilliformis has been identified. The 1302 bp gene, termed ctpA, is located immediately upstream of the ialA gene and encodes a predicted nascent product of 434 amino acids, producing a mature protein of 411 amino acid residues. The Bartonella CtpA appears to undergo autolysis in vitro, producing multiple products of 43-46 kDa, and a second group of products of 36-37 kDa. Production of CtpA in vivo gives a single product of 41.8 kDa. In addition to a computer-predicted …
Possible Use Of Wading Birds As Beaters By Snail Kites, Boat-Tailed Grackles, And Limpkins, Robert E. Bennetts, Victoria J. Dreitz
Possible Use Of Wading Birds As Beaters By Snail Kites, Boat-Tailed Grackles, And Limpkins, Robert E. Bennetts, Victoria J. Dreitz
Wildlife Biology Faculty Publications
Foraging in single- or mixed-species flocks is common among many bird species, and the advantages of being in these flocks have been the focus of several investigations (reviewed by Moynihan 1962, Bertram 1978). It has been hypothesized that birds occurring in mixed-species flocks gain advantages from (1) reduced predation risk (e.g., Moynihan 1962, Morse 1970), (2) increased foraging efficiency (e.g., Moynihan 1962, Morse 1970), or (3) social learning (e.g., Ward and Zahavi 1973). Here, we report the anomalous occurrence of flocks consisting of species not typically found in the types of aggregations we describe and suggest the possible function of …
Reversion Rates In A Leub Auxotroph Of Escherichia Coli K-12 Correlate With Ppgpp Levels During Exponential Growth, Barbara E. Wright, Michael F. Minnick
Reversion Rates In A Leub Auxotroph Of Escherichia Coli K-12 Correlate With Ppgpp Levels During Exponential Growth, Barbara E. Wright, Michael F. Minnick
Biological Sciences Faculty Publications
Two isogenic strains of Escherichia coli K-12 differing only in relA, as well as two spoT transductants of the relA- strain, were examined with respect to ppGpp levels and reversion rates of a leuB- allele under nine different conditions. A positive correlation was established between reversion rates and the steady-state concentration of ppGpp during exponential growth. The leuB genes from two leuB- strains (isogenic except for relA) were cloned and sequenced and found to contain a single mutation, namely, a C-to-T transition at nucleotide 857. This mutation resulted in a serine-to-leucine substitution at amino acid residue 286 of the LeuB …
Ophiostoma Clavigerum Is The Mycangial Fungus Of The Jeffrey Pine Beetle, Dendroctonus Jeffreyi, Diana Six, T. D. Paine
Ophiostoma Clavigerum Is The Mycangial Fungus Of The Jeffrey Pine Beetle, Dendroctonus Jeffreyi, Diana Six, T. D. Paine
Ecosystem and Conservation Sciences Faculty Publications
Dendroctonus jeffreyi and D. ponderosae are sibling species of bark beetles (Coleoptera: Scolyti- dae) with few morphological and molecular genetic differences. The two species are believed to have di- verged relatively recently. Dendroctonus jeffreyi colo- nizes only Pinus jeffreyi, while D. ponderosae colonizes up to thirteen Pinus spp., but not P. jeffreyi. Adult beetles of both D. jeffreyi and D. ponderosae carry sym- biotic fungi in mycangia located on the maxillary car- dines. Dendroctonus ponderosae was known to carry two fungi, Ophiostoma clavigerum and 0. montium, in its mycangia. However, it was not known which fungi might be carried by …
Conservation Implications Of A Multi-Scale Study Of Flammulated Owl (Otus Flammeolus) Habitat Use In The Northern Rocky Mountains, Usa, Vita Wright, Sallie J. Hejl, Richard L. Hutto
Conservation Implications Of A Multi-Scale Study Of Flammulated Owl (Otus Flammeolus) Habitat Use In The Northern Rocky Mountains, Usa, Vita Wright, Sallie J. Hejl, Richard L. Hutto
Biological Sciences Faculty Publications
Our multi-scale analysis of Flammulated Owl (Otus flammeolus) habitat use in the northern Rocky Mountains indicates some landscapes may be unsuitable for this species. As a result, there may be less habitat available for Flammulated Owls than thought based on the results of microhabitat studies. Thus, we suggest Flammulated Owl habitat conservation measures be based on the results of landscape-level, as well as microhabitat studies. Habitat conservation and restoration efforts in the ponderosa pine ecosystem should retain large trees, large snags, understory tree thickets, and grassland openings within landscapes that contain an abundance of suitable forest types.
G Protein Mechanisms: Insights From Structural Analysis, Stephen R. Sprang
G Protein Mechanisms: Insights From Structural Analysis, Stephen R. Sprang
Biological Sciences Faculty Publications
This review is concerned with the structures and mechanisms of a superfamily of regulatory GTP hydrolases (G proteins). G proteins include Ras and its close homologs, translation elongation factors, and heterotrimeric G proteins. These proteins share a common structural core, exemplified by that of p21(ras) (Ras), and significant sequence identity, suggesting a common evolutionary origin. Three-dimensional structures of members of the G protein superfamily are considered in light of other biochemical findings about the function of these proteins. Relationships among G protein structures are discussed, and factors contributing to their low intrinsic rate of GTP hydrolysis are considered. Comparison of …
Recovery Of Crenarchaeotal Ribosomal Dna Sequences From Freshwater-Lake Sediments, Christa Schleper, William E. Holben, Hans-Peter Klenk
Recovery Of Crenarchaeotal Ribosomal Dna Sequences From Freshwater-Lake Sediments, Christa Schleper, William E. Holben, Hans-Peter Klenk
Biological Sciences Faculty Publications
We report several novel environmental sequences of archaea from the kingdom Crenarchaeota, recovered from anaerobic freshwater-lake sediments in Michigan. A nested PCR approach with Archaea- and Crenarchaeota-specific primers was used to amplify partial Small-subunit ribosomal DNAs. Phylogenetic analysis of seven sequences shows that these DNAs represent a monophyletic lineage diverging prior to all recently identified crenarchaeotal phylotypes isolated from temperate environments. Including our lineage, all uncultured crenarchaeotal sequences recovered from moderate or told environments form a distinct, monophyletic group separate from the ''genuine'' thermophilic crenarchaeota. Our finding extends the emerging picture that crenarchaeota, thought until recently to be solely extreme …