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Molecular cloning and physical and functional characterization of the Salmonella typhimurium and Salmonella typhi galactose utilization operons.
J Bacteriol. 1990 Aug; 172(8):4392-8.JB

Abstract

The chromosomally encoded galactose utilization (gal) operons of Salmonella typhimurium and S. typhi were each cloned on similar 5.5-kilobase HindIII fragments into pBR322 and were identified by complementation of Gal- Escherichia coli strains. Restriction endonuclease analyses indicated that these Salmonellae operons share considerable homology, but some heterogeneities in restriction sites were observed. Subcloning and exonuclease mapping experiments showed that both operons have the same genetic organization as that established for the E. coli gal operon (i.e., 5' end, promoter, epimerase, transferase, kinase, and 3' end). Two gal operator regions (oE and oI) of S. typhimurium, identified by repressor titration in an E. coli superrepressor [galR(Sup)] mutant, were sequenced and found to flank the promoter region. This promoter region is identical to the -10 and -35 regions of the E. coli gal operon. Minicell studies demonstrated that the three gal structural genes of S. typhimurium encode separate polypeptides of 39 kilodaltons (kDa) (epimerase, 337 amino acids [aa's]), 41 kDa (transferase, 348 aa's), and 43 kDa (kinase, 380 aa's). Despite functional and organizational similarities, DNA sequence analysis revealed that the S. typhimurium gal genes show less than 70% homology to the E. coli gal operon. Because of codon degeneracy, the deduced amino acid sequences of these polypeptides are highly conserved (greater than 90% homology) as compared with those of the E. coli gal enzymes. These studies have defined basic genetic parameters of the gal genes of two medically important Salmonella species, and our findings support the hypothesized divergent evolution of E. coli and Salmonella spp. from a common ancestral parent bacterium.

Authors+Show Affiliations

Department of Bacterial Immunology, Walter Reed Army Institute of Research, Washington, D.C. 20307.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

2198256

Citation

Houng, H S., et al. "Molecular Cloning and Physical and Functional Characterization of the Salmonella Typhimurium and Salmonella Typhi Galactose Utilization Operons." Journal of Bacteriology, vol. 172, no. 8, 1990, pp. 4392-8.
Houng HS, Kopecko DJ, Baron LS. Molecular cloning and physical and functional characterization of the Salmonella typhimurium and Salmonella typhi galactose utilization operons. J Bacteriol. 1990;172(8):4392-8.
Houng, H. S., Kopecko, D. J., & Baron, L. S. (1990). Molecular cloning and physical and functional characterization of the Salmonella typhimurium and Salmonella typhi galactose utilization operons. Journal of Bacteriology, 172(8), 4392-8.
Houng HS, Kopecko DJ, Baron LS. Molecular Cloning and Physical and Functional Characterization of the Salmonella Typhimurium and Salmonella Typhi Galactose Utilization Operons. J Bacteriol. 1990;172(8):4392-8. PubMed PMID: 2198256.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Molecular cloning and physical and functional characterization of the Salmonella typhimurium and Salmonella typhi galactose utilization operons. AU - Houng,H S, AU - Kopecko,D J, AU - Baron,L S, PY - 1990/8/1/pubmed PY - 1990/8/1/medline PY - 1990/8/1/entrez SP - 4392 EP - 8 JF - Journal of bacteriology JO - J Bacteriol VL - 172 IS - 8 N2 - The chromosomally encoded galactose utilization (gal) operons of Salmonella typhimurium and S. typhi were each cloned on similar 5.5-kilobase HindIII fragments into pBR322 and were identified by complementation of Gal- Escherichia coli strains. Restriction endonuclease analyses indicated that these Salmonellae operons share considerable homology, but some heterogeneities in restriction sites were observed. Subcloning and exonuclease mapping experiments showed that both operons have the same genetic organization as that established for the E. coli gal operon (i.e., 5' end, promoter, epimerase, transferase, kinase, and 3' end). Two gal operator regions (oE and oI) of S. typhimurium, identified by repressor titration in an E. coli superrepressor [galR(Sup)] mutant, were sequenced and found to flank the promoter region. This promoter region is identical to the -10 and -35 regions of the E. coli gal operon. Minicell studies demonstrated that the three gal structural genes of S. typhimurium encode separate polypeptides of 39 kilodaltons (kDa) (epimerase, 337 amino acids [aa's]), 41 kDa (transferase, 348 aa's), and 43 kDa (kinase, 380 aa's). Despite functional and organizational similarities, DNA sequence analysis revealed that the S. typhimurium gal genes show less than 70% homology to the E. coli gal operon. Because of codon degeneracy, the deduced amino acid sequences of these polypeptides are highly conserved (greater than 90% homology) as compared with those of the E. coli gal enzymes. These studies have defined basic genetic parameters of the gal genes of two medically important Salmonella species, and our findings support the hypothesized divergent evolution of E. coli and Salmonella spp. from a common ancestral parent bacterium. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/2198256/Molecular_cloning_and_physical_and_functional_characterization_of_the_Salmonella_typhimurium_and_Salmonella_typhi_galactose_utilization_operons_ L2 - https://journals.asm.org/doi/10.1128/jb.172.8.4392-4398.1990?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -