Polymerase delta-interacting protein 38 (PDIP38) modulates the stability and activity of the mitochondrial AAA+ protease CLPXP

Over a decade ago Polymerase δ interacting protein of 38 kDa (PDIP38) was proposed to play a role in DNA repair. Since this time, both the physiological function and subcellular location of PDIP38 has remained ambiguous and our present understanding of PDIP38 function has been hampered by a lack of detailed biochemical and structural studies. Here we show, that human PDIP38 is directed to the mitochondrion in a membrane potential dependent manner, where it resides in the matrix compartment, together with its partner protein CLPX. Our structural analysis revealed that PDIP38 is composed of two conserved domains separated by an α/β linker region. The N-terminal (YccV-like) domain of PDIP38 forms an SH3-like β-barrel, which interacts specifically with CLPX, via the adaptor docking loop within the N-terminal Zinc binding domain of CLPX. In contrast, the C-terminal (DUF525) domain forms an immunoglobin-like β-sandwich fold, which contains a highly conserved putative substrate binding pocket. Importantly, PDIP38 modulates the substrate specificity of CLPX and protects CLPX from LONM-mediated degradation, which stabilises the cellular levels of CLPX. Collectively, our findings shed new light on the mechanism and function of mitochondrial PDIP38, demonstrating that PDIP38 is a bona fide adaptor protein for the mitochondrial protease, CLPXP

The SPECTRA Barrax campaign (SPARC): Overview and first results from CHRIS data

In the framework of preparatory activities for the SPECTRA (Surface Processes and Ecosystems Changes Through Response Analysis) ESA Earth Explorer Core Mission, CHRIS/PROBA acquisitions over the Barrax Core Site in Spain were used to compile a reference dataset for future in-depth studies. Taking advantage of the possibility of consecutive days of acquisitions, multiple-angular acquisitions finally included 10 different view angles from CHRIS, in Mode 1 with 62 spectral, and a ground resolution of about 34 m. Additional ROSIS and HYMAP sensors, flying simultaneously with CHRIS overpass, provided detailed images for validation of CHRIS data, particularly in the spectral domain. Moreover, up to 3 angles per sample from airborne HYMAP data were acquired, with high spectral and spatial resolution, and then both spectral and angular domains can be exploited with the combined CHRIS/HYMAP/ROSIS dataset. Detailed soil/vegetation and atmospheric measurements complete the SPARC data, and data from other satellites (MERIS, SEVIRI, SPOT, Landsat) were collected as well, to address scaling issues. Methods for data analysis and exploitation have been developed in the context of SPARC activities, and preliminary results about retrievals of biophysical information from multi-angular hyperspectral data are already available. The whole SPARC dataset represents a reference for the exploitation of CHRIS data, allowing the development of new processing and retrieval algorithms, and the validation of such algorithms by means of ground measurements and complementary airborne and satellite data. More details on several processing aspects of the CHRIS/PROBA data acquired within the SPARC campaign are presented in other papers in this conference