The crystal structure of ternary and binary substrate complexes of the catalytic subunit of CAMP-dependent protein kinase has been refined at 2.2 and 2.25 A resolution, respectively. The ternary complex contains ADP and a 20-residue substrate peptide, whereas the binary complex contains the phosphorylated substrate peptide. These 2 structures were refined to crystallographic R-factors of 17.5 and 18.1'70, respectively. In the ternary complex, the hydroxyl oxygen OG of the serine at the P-site is 2.7 A from the OD1 atom of Asp 166. This is the first crystallographic evidence showing the direct interaction of this invariant carboxylate with a peptide substrate, and supports the predicted role of Asp 166 as a catalytic base and as an agent to position the serine -OH for nucleophilic attack. A comparison of the substrate and inhibitor ternary complexes places the hydroxyl oxygen of the serine 2.7 A from the y-phosphate of ATP and supports a direct in-line mechanism for phosphotransfer. In the binary complex, the phosphate on the Ser interacts directly with the EN of Lys 168, another conserved residue. In the ternary complex containing ATP and the inhibitor peptide, Lys 168 interacts electrostatically with the y-phosphate of ATP (Zheng J, Knighton DR, Ten Eyck LF, Karlsson R, Xuong NH, Taylor SS, Sowadski JM, 1993, Biochemistry 32:2154-2161). Thus, Lys 168 remains closely associated with the phosphate in both complexes. A comparison of this binary complex structure with the recently solved structure of the ternary complex containing ATP and inhibitor peptide also reveals that the phosphate atom traverses a distance of about 1.5 A following nucleophilic attack by serine and transfer to the peptide. No major conformational changes of active site residues are seen when the substrate and product complexes are compared, although the binary complex with the phosphopeptide reveals localized changes in conformation in the region corresponding to the glycine-rich loop. The high B-factors for this loop support the conclusion that this structural motif is a highly mobile segment of the protein.

The Spo0F-Spo0B interaction appears to be a prototype for response regulator-histidine kinase interactions. The primary contact surface between these two proteins is formed by hydrophobic regions in both proteins. The Spo0F residues making up the hydrophobic patch are very similar in all response regulators suggesting that the binding is initiated through the same residues in all interacting response regulator-kinase pairs. The bulk of the interactions outside this patch are through nonconserved residues. Recognition specificity is proposed to arise from interactions of the nonconserved residues, especially the hypervariable residues of the beta4-alpha4 loop.

Pastoralists and their livestock share much of the habitat of the snow leopard ( Uncia uncia) across south and central Asia. The levels of livestock predation by the snow leopard and other carnivores are high, and retaliatory killing by the herders is a direct threat to carnivore populations. Depletion of wild prey by poaching and competition from livestock also poses an indirect threat to the region's carnivores. Conservationists working in these underdeveloped areas that face serious economic damage from livestock losses have turned to incentive programs to motivate local communities to protect carnivores. We describe a pilot incentive program in India that aims to offset losses due to livestock predation and to enhance wild prey density by creating livestock-free areas on common land. We also describe how income generation from handicrafts in Mongolia is helping curtail poaching and retaliatory killing of snow leopards. However, initiatives to offset the costs of living with carnivores and to make conservation beneficial to affected people have thus far been small, isolated, and heavily subsidized. Making these initiatives more comprehensive, expanding their coverage, and internalizing their costs are future challenges for the conservation of large carnivores such as the snow leopard.El Papel de Programas de Incentivos en la Conservación del Uncia uncia Resumen: Pastores y su ganado comparten gran parte del hábitat del leopardo Uncia uncia en el centro y sur de Asia. Los niveles de depredación de ganado por leopardos y otros carnívoros son altos, y la matanza en represalia por pastores es una amenaza directa para las poblaciones de carnívoros. La reducción de presas silvestres por cacería furtiva y la exclusión competitiva por ganado también representa una amenaza indirecta para los carnívoros de la región. Los conservacionistas que trabajan en estasáreas no desarrolladas que enfrentan serios impactos económicos por pérdidas de ganado han impulsado programas de incentivos para motivar a las comunidades locales a que protejan a los carnívoros. Describimos un programa piloto de incentivos en India enfocado a reducir pérdidas debido a la depredación de ganado y a incrementar la densidad de presas silvestres mediante la creación deáreas libres de ganado en tierras comunales. También describimos como la generación de ingresos de artesanías en Mongolia esta ayudando a reducir la cacería furtiva y la matanza en represalia de Uncia uncia. Hasta ahora, sin embargo, las iniciativas para compensar los costos de convivir con carnívoros y hacer que la conservación sea benéfica para la gente afectada han sido pequeñas, aisladas y fuertemente subsidiadas. Hacer que estas iniciativas sean más integrales, aumenten su cobertura e internalicen sus costos son retos futuros para la conservación de carnívoros mayores tales como el leopardo Uncia uncia.

To understand the molecular mechanism underlying phosphoryl transfer of cAMP-dependent protein kinase, the structure of the catalytic subunit in complex with ADP, aluminum fluoride, Mg2+ ions and a substrate peptide was determined at 2.0 A resolution. Aluminum fluoride was modeled as AlF3 in a planar geometry; it is positioned 2.3 A from both the donor oxygen of ADP and the hydroxyl group of the recipient Ser residue. In this configuration, the aluminum atom forms a trigonal bipyramidal coordination with the oxygen atoms of the donor and recipient groups at the apical positions. This arrangement suggests that aluminum fluoride mimics the transition state and provides the first direct structural evidence for the in-line mechanism of phosphoryl transfer in a protein kinase.

Both the diversity and similarity of cAMP binding sites are demonstrated by this new type II regulatory subunit structure. The structure represents an intramolecular paradigm for the cooperative triad that links two cAMP binding sites through a domain interface to the catalytic subunit of cAMP-dependent protein kinase. The domain interface surface is created by the binding of only one cAMP molecule and is enabled by amino acid sequence variability within the peptide chain that tethers the two domains together.

Summary 1.Resource competition is an important process governing the impact of livestock on native wild mammalian herbivores, an issue acknowledged to be of global conservation concern. Resource competition occurs between species when their resources (habitat and diet) overlap and are limiting. Yet the evidence that livestock compete with wild herbivores has remained weak because resource limitation is often difficult to demonstrate in the field. 2. This 2-year field study at Bandipur National Park, India, examined livestock-mediated resource limitation among five wild herbivore species: wild pig Sus scrofa , chital Axis axis , sambar Cervus unicolor , gaur Bos gaurus and Asian elephant Elephas maximus , by comparing their distribution and densities in adjoining livestock-grazed and livestockfree areas before, and after, a 49% decline in livestock density. ), were, respectively, 132, 11 and six times higher in the livestock-free area than in the adjacent livestock-grazed area. Densities of gaur, chital and elephant showed a sharp declining relationship with increasing livestock density, whereas no clear pattern was discernible with wild pig, a non-ruminant generalist, and the sambar, a forest browser. Preferred plant biomass also fell sharply with increasing livestock density. 4. Following the decline in livestock density in the livestock-grazed area in 2002, the densities of gaur, chital and elephant increased by a factor of 57, five and two in the same area, respectively, whereas no changes were seen in the densities of wild pig and sambar or in the preferred plant biomass. Except for a decline in elephant density, the livestock-free area did not show changes in wild herbivore densities. 5. Given the considerable overlap in habitat and dietary preference/requirements between livestock and wild herbivores in the study area, it is suggested that the recovery of gaur, chital and elephant densities following the livestock decline represents their release from livestock-mediated resource limitation. 6. Synthesis and applications . These results indicate that resource competition may be intense between wild herbivores and grazing livestock, and if left unchecked could trigger declines of wild herbivores, particularly grazing ruminants and bulk feeders. These results also suggest that, where possible, interventions to reduce livestock grazing may rapidly benefit wild herbivores that have been competitively suppressed. This has important implications for the management of livestock grazing in India's wildlife reserves.

Conflict with humans over livestock and crops seriously undermines the conservation prospects of India's large and potentially dangerous mammals such as the tiger (Panthera tigris) and elephant (Elephas maximus). This study, carried out in Bhadra Tiger Reserve in south India, estimates the extent of material and monetary loss incurred by resident villagers between 1996 and 1999 in conflicts with large felines and elephants, describes the spatiotemporal patterns of animal damage, and evaluates the success of compensation schemes that have formed the mainstay of loss-alleviation measures. Annually each household lost an estimated 12% (0.9 head) of their total holding to large felines, and approximately 11% of their annual grain production (0.82 tonnes per family) to elephants. Compensations awarded offset only 5% of the livestock loss and 14% of crop losses and were accompanied by protracted delays in the processing of claims. Although the compensation scheme has largely failed to achieve its objective of alleviating loss, its implementation requires urgent improvement if reprisal against large wild mammals is to be minimized. Furthermore, innovative schemes of livestock and crop insurance need to be tested as alternatives to compensations.

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