1H, 13C and 15N resonance assignments of the GTPase-activating (GAP) and Ral binding domains (GBD) of RLIP76 (RalBP1)

Genotoxicity, anti-melanoma and antioxidant activities of Hymenaea courbaril L. seed extract

Hymenaea courbaril has been used to treat different diseases, although its properties are yet to be scientifically validated. The objective of this study was to determine the cytotoxicity, genotoxicity, antigenotoxicity and antioxidant potentials of hydroethanolic extract from H. courbaril seeds. Therefore, for the cytotoxicity test an anti-melanoma assay was performed in B16F10 strain cells. The genotoxicity and antigenotoxicity was evaluated in bone marrow cells (Permit number: 002/2010) of mice, the antioxidant activity was determined by the DPPH test and the total flavonoid content was also determined. The hydroethanolic extract showed antigenotoxic effect and antioxidant activity. It was verified that total flavonoid content was 442.25±18.03 mg RE/g dry extract. HPLC-PAD chromatogram revealed presence of flavones as majority compound in evaluated extract. The results allowed us to also infer that the hydroethanolic extract from seeds shows cytotoxic activity against B16F10 melanoma cells line and it has dose-and-time-dependency.

Exploiting image registration for automated resonance assignment in NMR

Analysis of protein NMR data involves the assignment of resonance peaks in a number of multidimensional data sets. To establish resonance assignment a three-dimensional search is used to match a pair of common variables, such as chemical shifts of the same spin system, in different NMR spectra. We show that by displaying the variables to be compared in two-dimensional plots the process can be simplified. Moreover, by utilizing a fast Fourier transform cross-correlation algorithm, more common to the field of image registration or pattern matching, we can automate this process. Here, we use sequential NMR backbone assignment as an example to show that the combination of correlation plots and segmented pattern matching establishes fast backbone assignment in fifteen proteins of varying sizes. For example, the 265-residue RalBP1 protein was 95.4% correctly assigned in 10 s. The same concept can be applied to any multidimensional NMR data set where analysis comprises the comparison of two variables. This modular and robust approach offers high efficiency with excellent computational scalability and could be easily incorporated into existing assignment software.

The structure of the RLIP76 RhoGAP-Ral binding domain dyad: fixed position of the domains leads to dual engagement of small G proteins at the membrane

RLIP76 is an effector for Ral small GTPases, which in turn lie downstream of the master regulator Ras. Evidence is growing that Ral and RLIP76 play a role in tumorigenesis, invasion, and metastasis. RLIP76 contains both a RhoGAP domain and a Ral binding domain (GBD) and is, therefore, a node between Ras and Rho family signaling. The structure of the RhoGAP-GBD dyad reveals that the RLIP76 RhoGAP domain adopts a canonical RhoGAP domain structure and that the linker between the two RLIP76 domains is structured, fixing the orientation of the two domains and allowing RLIP76 to interact with Rho-family GTPases and Ral simultaneously. However, the juxtaposed domains do not influence each other functionally, suggesting that the RLIP76-Ral interaction controls cellular localization and that the fixed orientation of the two domains orientates the RhoGAP domain with respect to the membrane, allowing it to be perfectly poised to engage its target G proteins.