Increasing intracellular magnesium levels with the 31-amino acid MgtS protein.

Synthesis of the 31-amino acid, inner membrane protein MgtS (formerly denoted YneM) is induced by very low Mg in a PhoPQ-dependent manner in Here we report that MgtS acts to increase intracellular Mg levels and maintain cell integrity upon Mg depletion. Upon development of a functional tagged derivative of MgtS, we found that MgtS interacts with MgtA to increase the levels of this P-type ATPase Mg transporter under Mg-limiting conditions. Correspondingly, the effects of MgtS upon Mg limitation are lost in a ∆ mutant, and MgtA overexpression can suppress the ∆ phenotype.

The ubiquitous yybP-ykoY riboswitch is a manganese-responsive regulatory element.

The highly structured, cis-encoded RNA elements known as riboswitches modify gene expression upon binding a wide range of molecules. The yybP-ykoY motif was one of the most broadly distributed and numerous bacterial riboswitches for which the cognate ligand was unknown. Using a combination of in vivo reporter and in vitro expression assays, equilibrium dialysis, and northern analysis, we show that the yybP-ykoY motif responds directly to manganese ions in both Escherichia coli and Bacillus subtilis.

Association of RNAs with Bacillus subtilis Hfq.

The prevalence and characteristics of small regulatory RNAs (sRNAs) have not been well characterized for Bacillus subtilis, an important model system for Gram-positive bacteria. However, B. subtilis was recently found to synthesize many candidate sRNAs during stationary phase.

Expanding roles for metabolite-sensing regulatory RNAs.

Metabolite-sensing regulatory RNAs, oft referred to as riboswitches, are widely used among eubacteria for control of diverse biochemical pathways and transport mechanisms. Great strides have been made in understanding the general structure and biochemistry of individual riboswitch classes. However, along with these advancements, it has become clear that metabolite-sensing riboswitches respond to an increasingly structurally diverse range of metabolite and metal ligands.

K-Ras4B proteins are expressed in the nucleolus: Interaction with nucleolin.

Kirsten Ras4B (K-Ras4B) is a potent onco-protein that is expressed in the majority of human cell types and is frequently mutated in carcinomas. K-Ras4B, like other members of the Ras family of proteins, is considered to be a cytoplasmic protein that must be localized to the plasma membrane for activation. Here, using confocal microscopy and biochemical analysis, we show that K-Ras4B, but not H-Ras or the closely related K-Ras4A, is also present in the nucleoli of normal and transformed cells.

Tuberous sclerosis complex 2 gene product interacts with human SMAD proteins. A molecular link of two tumor suppressor pathways.

Tuberin (TSC2) is a tumor suppressor gene. At the cellular level, tuberin is required as a critical regulator of cell growth, neuronal differentiation, and tumor suppression. Here we report a critical role for tuberin in late stage myeloid cell differentiation.