ELUCIDATION OF THE MOLECULAR MECHANISMS OF ACTION OF PINI

The enzyme Pinl is a peptidyl-prolyl isomerase (PPIase) that structurally consists of an N-terminal WW interaction domain and a C-terminal catalytic or PPIase domain. The understanding of how these two domains work together and perform the many functions discovered in cells is incomplete. Therefore, we hypothesize that Pinl acts as an extra regulatory step in signalling pathways by first binding to targets with its WW domain and then catalyzing the isomerization of those same proteins using its PPIase domain. To gain insights into how Pinl performs its molecular function, we mutated specific residues of Pinl and examined both their ability to support viability in yeast and isomerase activity. We determined that in the phospho-specific binding loop of the PPIase domain K63 was the most important basic residue for Pinl function and activity while only one contact from R68 or R69 was needed. Furthermore, by mutating the Pinl catalytic residue, Cl 13, to both D and S, we showed that a negative charge at this position is more important than a nucleophile. Finally, extensive mutagenesis of two conserved active site histidines, H59 and HI57, determined that these two residues are not as important as Cl 13 for Pinl function or activity. Instead, protein stability experiments suggested a structural role for both histidines. Collectively, these results led us to propose a new non-covalent mechanism for Pinl catalysis. We also examined the binding of Pinl mutants to full-length targets and surprisingly found that a binding-deficient mutation in the PPIase domain, R68/69A, had a lower affinity for most Pinl targets. We also discovered two classes of Pinl binding proteins: Class I proteins bind both the WW and PPIase domains of Pinl while Class II proteins mainly bind the WW. We proposed, based upon structures of the WW and PPIase domains bound to peptides, that the differences between Class I and Class II binding may relate to the presence of a proline at the +1 position. These results have provided novel insights into the binding of the two domains of Pin 1 to full-length targets. Taken together, these studies have expanded the knowledge of the molecular mechanisms of Pinl action in cells

The Reporter, May 20, 1981

The Reporter was Baruch College\u27s evening session newspaper. Founded in 1923, when Baruch College was still part of City College, the Reporter billed itself as the Oldest Evening Session College Newspaper Published in the United States. It ceased publication in 2002

A Gain-of-Function Germline Mutation in Drosophila ras1 Affects Apoptosis and Cell Fate during Development

The RAS/MAPK signal transduction pathway is an intracellular signaling cascade that transmits environmental signals from activated receptor tyrosine kinases (RTKs) on the cell surface and other endomembranes to transcription factors in the nucleus, thereby linking extracellular stimuli to changes in gene expression. Largely as a consequence of its role in oncogenesis, RAS signaling has been the subject of intense research efforts for many years. More recently, it has been shown that milder perturbations in Ras signaling during embryogenesis also contribute to the etiology of a group of human diseases. Here we report the identification and characterization of the first gain-of-function germline mutation in Drosophila ras1 (ras85D), the Drosophila homolog of human K-ras, N-ras and H-ras. A single amino acid substitution (R68Q) in the highly conserved switch II region of Ras causes a defective protein with reduced intrinsic GTPase activity, but with normal sensitivity to GAP stimulation. The ras1R68Q mutant is homozygous viable but causes various developmental defects associated with elevated Ras signaling, including cell fate changes and ectopic survival of cells in the nervous system. These biochemical and functional properties are reminiscent of germline Ras mutants found in patients afflicted with Noonan, Costello or cardio-facio-cutaneous syndromes. Finally, we used ras1R68Q to identify novel genes that interact with Ras and suppress cell death

Multiparental mapping of plant height and flowering time QTL in partially isogenic sorghum families.

Sorghum varieties suitable for grain production at temperate latitudes show dwarfism and photoperiod insensitivity, both of which are controlled by a small number of loci with large effects. We studied the genetic control of plant height and flowering time in five sorghum families (A-E), each derived from a cross between a tropical line and a partially isogenic line carrying introgressions derived from a common, temperate-adapted donor. A total of 724 F2:3 lines were phenotyped in temperate and tropical environments for plant height and flowering time and scored at 9139 SNPs using genotyping-by-sequencing. Biparental mapping was compared with multiparental mapping in different subsets of families (AB, ABC, ABCD, and ABCDE) using both a GWAS approach, which fit each QTL as a single effect across all families, and using a joint linkage approach, which fit QTL effects as nested within families. GWAS using all families (ABCDE) performed best at the cloned Dw3 locus, whereas joint linkage using all families performed best at the cloned Ma1 locus. Both multiparental approaches yielded apparently synthetic associations due to genetic heterogeneity and were highly dependent on the subset of families used. Comparison of all mapping approaches suggests that a GA2-oxidase underlies Dw1, and that a mir172a gene underlies a Dw1-linked flowering time QTL

Off-line Recognition of Printed Mathematical Expressions Using Stochastic Context-Free Grammars

Off-line recognition of printed mathematical expressions consists of three major steps: segmentation, symbol recognition and structural analysis. In this work we study an approach based on a twodimensional extension of context-free grammars parsing. Finally, some experiments are reported to evaluate the developed system.Álvaro Muñoz, F. (2010). Off-line Recognition of Printed Mathematical Expressions Using Stochastic Context-Free Grammars. http://hdl.handle.net/10251/13732Archivo delegad