Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.2.13 (aldolase)
 3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complete nucleotide sequences of lacRABCDF and partial nucleotide sequence of lacE from the lactose operon of Streptococcus mutans are presented. Comparison of the streptococcal lac determinants with those of Staphylococcus aureus and Lactococcus lactis indicate exceptional protein and nucleotide identity. The deduced polypeptides also demonstrate significant, but lower, sequence similarity with the corresponding lactose proteins of Lactobacillus casei. Additionally, LacR has sequence homology with the repressor (DeoR) of the Escherichia coli deoxyribonucleotide operon, while LacC is similar to phosphokinases (FruK and PfkB) from E. coli. The primary translation products of the lacRABCDFE genes are polypeptides of 251 (M(r) 28,713), 142 (M(r) 15,610), 171 (M(r) 18,950), 310 (M(r) 33,368), 325 (M(r) 36,495), 104 (M(r) 11,401), and 123 (NH2-terminal) amino acids, respectively. As inferred from their direct homology to the staphylococcal lac genes, these determinants would encode the repressor of the streptococcal lactose operon (LacR), galactose-6-phosphate isomerase (LacA and LacB), tagatose-6-phosphate kinase (LacC), tagatose-1,6-bisphosphate aldolase (LacD), and the sugar-specific components enzyme III-lactose (LacF) and enzyme II-lactose (LacE) of the S. mutans phosphoenolpyruvate-dependent phosphotransferase system. The nucleotide sequence encompassing the S. mutans lac promoter appears to contain repeat elements analogous to those of S. aureus, suggesting that repression and catabolite repression of the lactose operons may be similar in these organisms.
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PMID:Nucleotide and deduced amino acid sequences of the lacR, lacABCD, and lacFE genes encoding the repressor, tagatose 6-phosphate gene cluster, and sugar-specific phosphotransferase system components of the lactose operon of Streptococcus mutans. 140 Jan 64

The tagatose 6-phosphate pathway gene cluster (lacABCD) encoding galactose-6-phosphate isomerase, tagatose-6-phosphate kinase, and tagatose-1,6-diphosphate aldolase of Lactococcus lactis subsp. lactis MG1820 has been characterized by cloning, nucleotide sequence analysis, and enzyme assays. Transcription studies showed that the four tagatose 6-phosphate pathway genes are the first genes of the lactose-inducible lactose-phosphotransferase operon consisting of the lacABCDFEGX genes. Using a T7 expression system, it could be shown that the lacA, lacB, lacC, and lacD genes code for proteins with apparent molecular masses of 15, 19, 33, and 36 kDa, respectively. Cell-free extracts of induced and noninduced Escherichia coli cells expressing the lacABCD genes were used to determine the functions of the encoded proteins. Expression of both lacA and lacB was required to obtain galactose-6-phosphate isomerase activity. The lacC gene codes for tagatose-6-phosphate kinase, the deduced amino sequence of which is similar to that of E. coli Pfk-2 phosphofructokinase, and Staphylococcus aureus LacC protein. The tagatose-1,6-diphosphate aldolase is encoded by the lacD gene, and its deduced primary sequence, which is homologous to that of the S. aureus LacD protein, predicts an amino acid composition which is virtually identical to that of the previously purified L. lactis E8 tagatose-1,6-diphosphate aldolase.
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PMID:Molecular cloning, characterization, and nucleotide sequence of the tagatose 6-phosphate pathway gene cluster of the lactose operon of Lactococcus lactis. 190 63