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PMID:1400164

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Citation

Rosey, EL and Stewart, GC (1992) 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. J. Bacteriol. 174:6159-70

Abstract

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.

Links

PubMed PMC207683

Keywords

Amino Acid Sequence; Bacterial Proteins; Base Sequence; DNA-Binding Proteins; Escherichia coli Proteins; Genes, Bacterial/genetics; Hexosephosphates/metabolism; Lac Operon/genetics; Lactose/metabolism; Membrane Transport Proteins/genetics; Molecular Sequence Data; Monosaccharide Transport Proteins; Nucleic Acid Hybridization; Promoter Regions, Genetic; Protein Biosynthesis; Protein Conformation; Repressor Proteins/genetics; Sequence Homology; Streptococcus mutans/genetics; Symporters

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

STAAU:LACA

GO:0050044: galactose-6-phosphate isomerase activity

ECO:0000314:

F

Figure 1: DNA hybridation. Chromosomal DNA from S. mutants.

complete

STRMU:LACC

GO:0009024 : tagatose-6-phosphate kinase activity

ECO:0000247:

UniProtKB:P06999


F

Fig. 5 shows significant homology of the LacC protein of S. mutans with that of PfkB from E. coli that has evidence of tagatose-6-phosphate kinase activity.

complete
CACAO 3830

STRMU:LACC

enables

GO:0009024: tagatose-6-phosphate kinase activity

ECO:0000247: sequence alignment evidence used in manual assertion

UniProtKB:P06999

F

Seeded From UniProt

complete

LACLL:LACC

GO:0009024: tagatose-6-phosphate kinase activity

ECO:0000247:

UniProtKB:P06999


F

As seen in Fig. 5, LacC proteins of L. lactis exhibits direct homology to pfkB from E. coli which has evidence of tagatose-6-phosphate kinase activity.

complete


See also

References

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