The principal forms of amino nitrogen transported in xylem were studied in nodulated and non-nodulated peanut (Arachis hypogaea L.). In symbiotic plants, asparagine and the nonprotein amino acid, 4-methyleneglutamine, were identified as the major components of xylem exudate collected from root systems decapitated below the lowest nodule or above the nodulated zone. Sap bleeding from detached no...

Salmonellae are pathogenic bacteria that induce immunosuppression by mechanisms that remain largely unknown. Previously, we showed that a putative type II l-asparaginase produced by Salmonella Typhimurium inhibits T cell responses and mediates virulence in a murine model of infection. Here, we report that this putative L-asparaginase exhibits L-asparagine hydrolase activity required for Salmone...

Asparagine residues in proteins undergo spontaneous deamidation, a post-translational modification that may act as a molecular clock for the regulation of protein function and turnover. Asparagine deamidation is modulated by protein local sequence, secondary structure and hydrogen bonding. We present NGOME, an algorithm able to predict non-enzymatic deamidation of internal asparagine residues i...

The Bacillus subtilis McpB is a class III chemotaxis receptor, from which methanol is released in response to all stimuli. McpB has four putative methylation sites based upon the Escherichia coli consensus sequence. To explore the nature of methanol release from a class III receptor, all combinations of putative methylation sites Gln(371), Gln(595), Glu(630), and Glu(637) were substituted with ...

Autotransporters are secreted proteins produced by pathogenic Gram-negative bacteria. They consist of a membrane-embedded β-domain and an extracellular passenger domain that is sometimes cleaved and released from the cell surface. We solved the structures of three noncleavable mutants of the autotransporter EspP to examine how it promotes asparagine cyclization to cleave its passenger. We found...

Asparagine and aspartate are known to adopt conformations in the left-handed alpha-helical region and other partially allowed regions of the Ramachandran plot more readily than any other non-glycyl amino acids. The reason for this preference has not been established. An examination of the local environments of asparagine and aspartic acid in protein structures with a resolution better than 1.5 ...

The minimum requirements for eliciting or enhancing ornithine decarboxylase activity (EC. 4.1.1.17); L-ornithine carboxylase) in neuroblastoma cells incubated in salts-glucose solutions have been investigated. These incubation conditions permit the study of changes in ornithine decarboxylase activity independently of the growth-associated reactions that occur in cell culture media (Chen, K.Y. a...

The ATP binding cassette (ABC) proteins make up a large superfamily with members coming from all kingdoms. The functional form of the ABC protein nucleotide binding domain (NBD) is dimeric with ATP binding sites shared between subunits. The NBD is defined by six motifs: the Walker A, Q-loop, Signature, Walker-B, D-loop, and H-loop. The D-loop contains a conserved aspartate whose function is not...