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Biomedical subjects

J Register

Publications and source records attributed to J Register.

12 recordsLinked to original sources
PubMed2000

The 1.7 A crystal structure of human cell cycle checkpoint kinase Chk1: implications for Chk1 regulation.

The checkpoint kinase Chk1 is an important mediator of cell cycle arrest following DNA damage. The 1.7 A resolution crystal structures of the human Chk1 kinase domain and its binary complex with an ATP analog has revealed an identical open kinase conformation. The secondary structure and side chain interactions stabilize the activation loop of Chk1 and enable kinase activity without phosphorylation of the catalytic domain. Molecular modeling of the interaction of a Cdc25C peptide with Chk1 has uncovered several conserved residues that are important for substrate selectivity. In addition, we found that the less conserved C-terminal region negatively impacts Chk1 kinase activity.

Catalytic Domain↗
PubMed1998

Reversible male sterility: a novel system for the production of hybrid corn.

Hybrid corn seed is traditionally produced using either mechanical/hand detasseling or cytoplasmic male sterility, or a combination of both. In recent years, the development of transgenic systems to produce hybrid seed in several crops has attracted much attention. Here we describe a transgenic mechanism for production of hybrid corn, reversible male sterility (RMS), in which the action of the cytotoxic gene used to introduce male sterility is suppressed by the application of a chemical to the plant. Reversion of the sterility allows the RMS parent to be self-fertilized, a step which overcomes the need to remove fertile sib plants prior to making the hybrid cross. The key enabling technology in RMS is the use of a plant gene promoter which is specifically induced by chemical application. We have exemplified RMS in transgenic corn plants and believe that it provides specific benefits in the production of hybrid corn seed.

Hybridization, Genetic↗
PubMed1984

Visualization of SSB-ssDNA complexes active in the assembly of stable RecA-DNA filaments.

We have demonstrated that SSB binds to ssDNA in a complex manner, producing two fundamentally different structures: one that appears as a nucleosomal chain of beads and linkers, and the other as a smooth-contoured, extended nucleoprotein filament. Under physiologic salt conditions, only the beaded complexes were observed. Experiments indicate that the highly beaded forms are the most active in the assembly of the stable RecA-ssDNA filaments. These results further support our previous suggestion (Chrysogelos and Griffith 1982) that the protein-free linker regions are important in two ways. First, they provide access to the DNA template, and second, they provide a means for the two proteins to associate one with the other when bound to ssDNA. We suggest here that SSB should be considered as an assembly factor for RecA in its binding to ssDNA. Furthermore, our results argue that once RecA has associated with both the ssDNA template and SSB, some structural alteration in the (ATP-primed) RecA must occur that nucleates the formation of the very ordered, helical RecA filament along the ssDNA.

DNA, Bacterial↗