Organization and nucleotide sequence of the glutamine synthetase (glnA) gene from Lactobacillus delbrueckii subsp. bulgaricus.
A 3.3-kb BamHI fragment of Lactobacillus delbrueckii subsp. bulgaricus DNA was cloned and sequenced. It complements an Escherichia coli glnA deletion strain and hybridizes strongly to a DNA containing the Bacillus subtilis glnA gene. DNA sequence analysis of the L. delbrueckii subsp. bulgaricus DNA showed it to contain the glnA gene encoding class I glutamine synthetase, as judged by extensive homology with other prokaryotic glnA genes. The sequence suggests that the enzyme encoded in this gene is not controlled by adenylylation. Based on a comparison of glutamine synthetase sequences, L. delbrueckii subsp. bulgaricus is much closer to gram-positive eubacteria, especially Clostridium acetobutylicum, than to gram-negative eubacteria and archaebacteria. The fragment contains another open reading frame encoding a protein of unknown function consisting of 306 amino acids (ORF306), which is also present upstream of glnA of Bacillus cereus. In B. cereus, a repressor gene, glnR, is found between the open reading frame and glnA. Two proteins encoded by the L. delbrueckii subsp. bulgaricus gene were identified by the maxicell method; the sizes of these proteins are consistent with those of the open reading frames of ORF306 and glnA. The lack of a glnR gene in the L. delbrueckii subsp. bulgaricus DNA in this position may indicate a gene rearrangement or a different mechanism of glnA gene expression.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511.
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Y
Ishino
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Morgenthaler
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H
Hottinger
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Söll
D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D005822:Genetic Vectors; D005974:Glutamate-Ammonia Ligase / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D007778:Lactobacillus / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids; D017386:Sequence Homology, Amino Acid
D005974:Glutamate-Ammonia Ligase