TaxisPy: A Python-based software for the quantitative analysis of bacterial chemotaxis.

Several species of bacteria are able to modify their swimming behavior in response to chemical attractants or repellents. Methods for the quantitative analysis of bacterial chemotaxis such as quantitative capillary assays are tedious and time-consuming. Computer-based video analysis of swimming bacteria represents a valuable method to directly assess their chemotactic response.

Hybrid Two-Component Sensors for Identification of Bacterial Chemoreceptor Function.

Soil bacteria adapt to diverse and rapidly changing environmental conditions by sensing and responding to environmental cues using a variety of sensory systems. Two-component systems are a widespread type of signal transduction system present in all three domains of life and typically are comprised of a sensor kinase and a response regulator. Many two-component systems function by regulating gene expression in response to environmental stimuli.

Alanine Scanning of YbdZ, an MbtH-like Protein, Reveals Essential Residues for Functional Interactions with Its Nonribosomal Peptide Synthetase Partner EntF.

Nonribosomal peptide synthetases (NRPSs) are megasynthetases that require complex and specific interactions between multiple domains and proteins to functionally produce a metabolite. MbtH-like proteins (MLPs) are integral components of many NRPSs and interact directly with the adenylation domain of the megasynthetases to stimulate functional enzymology. All of the MLP residues that are essential for functional interactions between the MLP and NRPS have yet to be defined.

Characterization of the Functional Variance in MbtH-like Protein Interactions with a Nonribosomal Peptide Synthetase.

Many nonribosomal peptide synthetases (NRPSs) require MbtH-like proteins (MLPs) for solubility or for activation of amino acid substrate by the adenylation domain. MLPs are capable of functional crosstalk with noncognate NRPSs at varying levels. Using enterobactin biosynthesis in Escherichia coli as a model MLP-dependent NRPS system, we use in vivo and in vitro techniques to characterize how seven noncognate MLPs influence the function of the enterobactin NRPS EntF when the cognate MLP, YbdZ, is absent.

Endogenous synthesis of 2-aminoacrylate contributes to cysteine sensitivity in Salmonella enterica.

RidA, the archetype member of the widely conserved RidA/YER057c/UK114 family of proteins, prevents reactive enamine/imine intermediates from accumulating in Salmonella enterica by catalyzing their hydrolysis to stable keto acid products. In the absence of RidA, endogenous 2-aminoacrylate persists in the cellular environment long enough to damage a growing list of essential metabolic enzymes. Prior studies have focused on the dehydration of serine by the pyridoxal 5'-phosphate (PLP)-dependent serine/threonine dehydratases, IlvA and TdcB, as sources of endogenous 2-aminoacrylate.