Crystal structure of Thermus aquaticus Gfh1, a Gre-factor paralog that inhibits rather than stimulates transcript cleavage.

Transcription elongation in bacteria is promoted by Gre-factors, which stimulate an endogenous, endonucleolytic transcript cleavage activity of the RNA polymerase. A GreA paralog, Gfh1, present in Thermus aquaticus and Thermus thermophilus, has the opposite effect on elongation complexes, inhibiting rather than stimulating transcript cleavage. We have determined the 3.

Spatial regulation of the cAMP-dependent protein kinase during chemotactic cell migration.

Historically, the cAMP-dependent protein kinase (PKA) has a paradoxical role in cell motility, having been shown to both facilitate and inhibit actin cytoskeletal dynamics and cell migration. In an effort to understand this dichotomy, we show here that PKA is regulated in subcellular space during cell migration. Immunofluorescence microscopy and biochemical enrichment of pseudopodia showed that type II regulatory subunits of PKA and PKA activity are enriched in protrusive cellular structures formed during chemotaxis.

Regulation of vasodilator-stimulated phosphoprotein phosphorylation and interaction with Abl by protein kinase A and cell adhesion.

Members of the vasodilator-stimulated phosphoprotein (VASP) family are important regulators of actin cytoskeletal dynamics whose functions and protein-protein interactions are regulated by phosphorylation by the cAMP-dependent protein kinase (PKA). Herein, we show that phosphorylation of VASP is dynamically regulated by cellular adhesion to extracellular matrix. Detachment of cells stimulated PKA activity and induced PKA-dependent phosphorylation of VASP and the related murine-Enabled (Mena) protein.

Cell adhesion differentially regulates the nucleocytoplasmic distribution of active MAP kinases.

Cells decide whether to undergo processes, such as proliferation, differentiation and apoptosis, based upon the cues they receive from both circulating factors and integrin-mediated adhesion to the extracellular matrix. Integrins control the activation of the early signaling pathways. For example, growth factor activation of the ERK cascade is enhanced when cells are adherent.

Transcript cleavage by Thermus thermophilus RNA polymerase. Effects of GreA and anti-GreA factors.

All known multisubunit RNA polymerases possess the ability to endonucleolytically degrade the nascent RNA transcript. To gain further insight into the conformational changes that govern transcript cleavage, we have examined the effects of certain anions on the intrinsic transcript cleavage activity of Thermus thermophilus RNA polymerase. Our results indicate that the conformational transitions involved in transcript cleavage, and therefore backtracking, are anion-dependent.