Disease relevance of leuB

• We also constructed an integration vector, which consisted of the Escherichia coli plasmid vector pBluescript and a 2.1-kb segment of the T. thermophilus leu operon sequence, for the integration of a foreign gene into a chromosome of the thermophile. pyrE and leuB genes were used as probes to test the integration vector [1].
• A library of Desulfovibrio desulfuricans Norway genomic DNA was constructed in Escherichia coli with pBR322 as vector and plasmids able to complement the proA and leuB mutations of the host were screened [2].
• Crystal structures of Escherichia coli and Salmonella typhimurium 3-isopropylmalate dehydrogenase and comparison with their thermophilic counterpart from Thermus thermophilus [3].
• A mutant plasmid with elevated expression efficiency of GC-rich Thermus thermophilus leuB gene was screened in Escherichia coli [4].
• Analysis of the leuB gene from Corynebacterium glutamicum [5].

High impact information on leuB

• To reveal the basis of the thermal stability of 3-isopropylmalate dehydrogenase (IPMDH) from an extreme thermophile, Thermus thermophilus, urea-induced unfolding of the enzyme and of its mesophilic counterpart from Escherichia coli has been studied [6].
• The cloned gene also allowed growth of a Escherichia coli leuB mutant in leucine-lacking medium, indicating that it encodes a product able to complement the beta-isopropylmalate dehydrogenase deficiency of the mutants [7].
• A thermostabilized mutant of Bacillus subtilis 3-isopropylmalate dehydrogenase (IPMDH) obtained in a previous study contained a set of triple amino acid substitutions [8].
• Sequence analysis of the plasmid showed that a 258-bp leader ORF overlapped with the initiation codon of leuB was newly formed as a consequence of the insertion of a 0.5-kb BamHI fragment derived from the E. coli chromosome [9].
• The GC-rich leuB gene (coding for 3-isopropylmalate dehydrogenase) of Thermus thermophilus is scarcely expressed in Escherichia coli, unless a leader open reading frame (ORF) is provided [9].

Biological context of leuB

• The PIR data base was searched and the enzyme 3-isopropylmalate dehydrogenase from six different micro-organisms was found to share significant amino acid sequence similarity (43-57%) with the 38.8 kDa L. interrogans leuB gene product [10].
• The nucleotide sequence of the C. glutamicum leuB coding region (an open reading frame, ORF, of 1020 bp encoding a polypeptide of 340 amino acids with M(r) of 36 144) was determined [5].
• The transcriptional start site of the leuB gene was localized 35 bp upstream of its translational start; a functional terminator was detected in the 3' flanking region [5].

Associations of leuB with chemical compounds

• Activity of the leuB promoter was significantly reduced when leucine was present in the growth medium [5].

Analytical, diagnostic and therapeutic context of leuB

• Molecular cloning of the leuB genes from Mycobacterium bovis BCG and Mycobacterium tuberculosis [11].
• Further improvement of the thermal stability of a partially stabilized Bacillus subtilis 3-isopropylmalate dehydrogenase variant by random and site-directed mutagenesis [8].

References