A computing engine, theProtein Structure Analysis Package(PSAP), has been developed to calculate and display various hidden structural and functional features of three-dimensional protein structures. The proposed computing engine has several utilities to enable structural biologists to analyze three-dimensional protein molecules and provides an easy-to-use Web interface to compute and visualize the necessary features dynamically on the client machine. Users need to provide the Protein Data Bank (PDB) identification code or upload three-dimensional atomic coordinates from the client machine. For visualization, the free molecular graphics programsRasMolandJmolare deployed in the computing engine. Furthermore, the computing engine is interfaced with an up-to-date local copy of the PDB. The atomic coordinates are updated every week and hence users can access all the structures available in the PDB. The computing engine is free and is accessible online at http://iris.physics.iisc.ernet.in/psap/.

The genome of a multi-cellular organism acquires various functional capabilities in different cell types by means of distinct chromatin modifications and packaging states. Acquired during early development, the cell type-specific epigenotype is maintained by cellular memory mechanisms that involve epigenetic modifications. Here we present the epigenetic status of the euchromatic region of the human Y chromosome that has mostly been ignored in earlier whole genome epigenetic mapping studies. Using ChIP-on-chip approach, we mapped H3K9ac, H3K9me3, H3K27me3 modifications and CTCF binding sites while DNA methylation analysis of selected CpG islands was done using bisulfite sequencing. The global pattern of histone modifications observed on the Y chromosome reflects the functional state and evolutionary history of the sequences that constitute it. The combination of histone and DNA modifications, along with CTCF association in some cases, reveals the transcriptional potential of all protein coding genes including the sex-determining gene SRY and the oncogene TSPY. We also observe preferential association of histone marks with different tandem repeats, suggesting their importance in genome organization and gene regulation. Our results present the first large scale epigenetic analysis of the human Y chromosome and link a number of cis-elements to epigenetic regulatory mechanisms, enabling an understanding of such mechanisms in Y chromosome linked disorders.

An Internet computing server has been developed to identify all the occurrences of the internal sequence repeats in a protein and DNA sequences. Further, an option is provided for the users to check the occurrence(s) of the resultant sequence repeats in the other sequence and structure (Protein Data Bank) databases. The databases deployed in the proposed computing engine are up-to-date and thus the users will get the latest information available in the respective databases. The server is freely accessible over the World Wide Web (WWW).Availabilityhttp://bioserver1.physics.iisc.ernet.in/fair/