Disease relevance of asnB

• Nucleotide sequence of Escherichia coli asnB and deduced amino acid sequence of asparagine synthetase B [1].
• Biochemical experiments and genomic sequence analysis showed that Deinococcus radiodurans and Thermus thermophilus do not possess asparagine synthetase (encoded by asnA or asnB), the enzyme forming asparagine from aspartate [2].
• Three asparagine synthetase genes, asnB, asnH, and asnO (yisO), were predicted from the sequence of the Bacillus subtilis genome [3].

High impact information on asnB

• The organism's capacity to make asparagine could be restored by transformation with Escherichia coli asnB [2].
• Site-directed mutagenesis and kinetic studies have been employed to identify amino acid residues involved in aspartate binding and transition state stabilization during the formation of beta-aspartyl-AMP in the reaction mechanism of Escherichia coli asparagine synthetase B (AS-B) [4].
• Mutagenesis and chemical rescue indicate residues involved in beta-aspartyl-AMP formation by Escherichia coli asparagine synthetase B [4].
• In the case of AS-B, although Cys-1 is essential for glutamine-dependent activity, Asp-33 does not appear to participate in mediating nitrogen transfer [5].
• Replacement of Asp-33 by either asparagine or glutamic acid has little effect on the kinetic properties of the mutant enzymes when compared to wild-type AS-B [5].

Chemical compound and disease context of asnB

• The Escherichia coli asparagine synthetase B gene (asnB) has been cloned into a temperature-sensitive, low copy plasmid, pOU71, as shown by the complementation of an E. coli asparagine auxotroph, E. coli JE6279 [1].
• We now report the overexpression, purification, and kinetic characterization of both the glutamine- and ammonia-dependent activities of Escherichia coli asparagine synthetase B (AS-B) and a series of mutants [5].
• Glutamic acid gamma-monohydroxamate and hydroxylamine are alternate substrates for Escherichia coli asparagine synthetase B [6].

Biological context of asnB

• The nucleotide sequence of asnB and the flanking sequences were determined [1].
• Transcription analyses revealed that asnB was possibly cotranscribed with a downstream gene, ytnA, while the asnH gene was transcribed as the fourth gene of an operon comprising yxbB, yxbA, yxnB, asnH, and yxaM [3].
• In contrast, deletion of asnB led to a slow-growth phenotype, even in the presence of asparagine [3].
• The implication of this model is that the two active sites in AS-B become coordinated only after formation of a beta-aspartyl-AMP intermediate in the synthetase site of the enzyme [7].
• The site-directed chemical modifier [p-(fluorosulfonyl)benzoyl]adenosine (5'-FSBA) inactivates Escherichia coli asparagine synthetase B activity following pseudo-first-order kinetics, with ATP providing specific protection, with a Kd of 12 microM [8].

Associations of asnB with chemical compounds

• A purF type glutamine amide transfer domain was identified upon inspection of the amino-terminal amino acid sequence of the asparagine synthetase B protein [1].
• Nitrogen transfer from LGH to yield aspartic acid beta-monohydroxamate is also catalyzed by AS-B [6].
• In addition, the kinetic parameters determined for hydroxylamine in AS-B synthetase activity are very similar to those of ammonia [6].
• While cysteine sulfinic acid did not itself constitute a clinically useful inhibitor of asparagine synthetase B, these results suggested that replacing this linkage by a more stable analogue might lead to a more potent inhibitor [9].
• Radiolabeled protein is not observed (i) when the wild-type enzyme is incubated with 6-diazo-5-oxo-L-norleucine (DON) prior to reaction with [14C]glutamine or (ii) when the C1A AS-B mutant is incubated with [14C]-L-glutamine [10].

References