Galactose-sensitive mutants of Salmonella I. Metabolism of galactose

Nikaido, Hiroshi

doi:10.1016/0006-3002(61)90044-0

Cited by 137 publications

(57 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Culture turbidity was determined in a KlettSummerson colorimeter with a blue filter. The addition of relatively low concentrations of galactose to cultures of galE mutants results in growth inhibition and autolysis (10). We observed that relA galE mutants were significantly more susceptible to galactose toxicity than were isogenic relA+ galE strains.…”

mentioning

confidence: 72%

Control of lipopolysaccharide biosynthesis and release by Escherichia coli and Salmonella typhimurium

Ishiguro¹,

Vanderwel²,

Kusser³

1986

J Bacteriol

View full text Add to dashboard Cite

The influence of the reLA gene on lipopolysaccharide (LPS) biosynthesis and release by Escherichia coli and Salmonella typhimurium was investigated. Similar results were obtained with both species. The incorporation of [3H]galactose into LPS by galE mutants was inhibited by at least 50% (as compared with normal growing controls) during amino acid deprivation of relA+ strains. This inhibition could be prevented by the treatment of the amino acid-deprived reLA+ bacteria with chloramphenicol, a known antagonist of the stringent control mechanism. Furthermore, LPS biosynthesis was not inhibited during amino acid deprivation of isogenic reLA mutant strains. These results indicate that LPS synthesis is regulated by the stringent control mechanism.Normal growing cells of both relA + and relA strains released LPS into the culture fluid at low rates. Amino acid deprivation stimulated the rate of LPS release by reLA mutants but not by relA+ bacteria. Chloramphenicol treatment markedly stimulated the release of cell-bound LPS by amino acid-deprived relA+ cells. Thus, a low rate of LPS release was characteristic of normal growth and could be increased in nongrowing cells by relaxing the control of LPS synthesis.During amino acid deprivation, the syntheses of several classes of macromolecules (e.g., stable RNA species, phospholipids, and peptidoglycan) are inhibited by a mechanism known as stringent control in relA+ strains of Escherichia coli (1,5). In contrast, the syntheses of these macromolecules continue in amino acid-deprived relA mutants, and this phenomenon is referred to as relaxed control. Two novel nucleotides, GTP 3'-diphosphate (pppGpp) and GDP 3'-diphosphate (ppGpp), accumulate during amino acid deprivation in relA+ bacteria but not in relA mutants, and at least one of these nucleotides may be the mediator of stringent control. Chloramphenicol is an antagonist of stringent control; i.e., treatment of amino acid-deprived relA+ bacteria with chloramphenicol prevents the accumulation of pppGpp and ppGpp and results in relaxed control.The possibility that lipopolysaccharide (LPS) synthesis in E. coli is regulated by the stringent control mechanism has been previously investigated in several laboratories (3, Bacterial strains. Strains IT5 (hisT1504 hisC508 galE) and IT18 (hisT1504 hisC508 galE relA2J::TnlO) were derivatives of S. typhimurium LT2. Strain IT18 was constructed by transducing the relA2J::TnlO marker from strain TT7428 (obtained from J. R. Roth, University of Utah, Salt Lake City) into strain IT5 with phage P22. The experiments described in this paper were originally performed with E. coli K-12 strains VC3 (thi-l lysA23 galE15) and VC50 (thi-1 lysA23 galE15 galK relA2). We noted that the rate of [3HJgalactose incorporation into LPS by strain VC50 was only about 20% of the rate in strain VC3. We now attribute the inefficient incorporation of galactose by strain VC50 to a spontaneous mutation in galK which apparently arose during laboratory subculture and which we were originally unaware of (we are indeb...

show abstract

mentioning

confidence: 72%

Control of lipopolysaccharide biosynthesis and release by Escherichia coli and Salmonella typhimurium

Ishiguro¹,

Vanderwel²,

Kusser³

1986

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…2A). Since it has been reported that galE mutants of a number of species accumulated intracellular Gal- 1-P and UDP-Gal in the presence of galactose, leading to bacteriostasis and bacteriolysis (8,26,30), we examined their growth in BHI-HM broth supplemented with galactose. Among the mutant strains, only the growth of the galE strain was delayed in the presence of more than 0.1% galactose (data not shown).…”

Section: Construction Of P Gingivalis Mutantsmentioning

confidence: 99%

Porphyromonas gingivalis galEIs Involved in Lipopolysaccharide O-Antigen Synthesis and Biofilm Formation

2006

View full text Add to dashboard Cite

Porphyromonas gingivalis is a crucial component of complex plaque biofilms that form in the oral cavity, resulting in the progression of periodontal disease. To elucidate the mechanism of periodontal biofilm formation, we analyzed the involvement of several genes related to the synthesis of polysaccharides in P. gingivalis. Gene knockout P. gingivalis mutants were constructed by insertion of an ermF-ermAM cassette; among these mutants, the galE mutant showed some characteristic phenotypes involved in the loss of GalE activity. As expected, the galE mutant accumulated intracellular carbohydrates in the presence of 0.1% galactose and did not grow in the presence of galactose at a concentration greater than 1%, in contrast to the parental strain. Lipopolysaccharide (LPS) analysis indicated that the length of the O-antigen chain of the galE mutant was shorter than that of the wild type. It was also demonstrated that biofilms generated by the galE mutant had an intensity 4.5-fold greater than those of the wild type. Further, the galE mutant was found to be significantly susceptible to some antibiotics in comparison with the wild type. In addition, complementation of the galE mutation led to a partial recovery of the parental phenotypes. We concluded that the galE gene plays a pivotal role in the modification of LPS O antigen and biofilm formation in P. gingivalis and considered that our findings of a relationship between the function of the P. gingivalis galE gene and virulence phenotypes such as biofilm formation may provide clues for understanding the mechanism of pathogenicity in periodontal disease.

show abstract

“…Grown in the presence of galactose, Salmonella enterica serotype Typhimurium galE mutants accumulate intracellular Gal-1-P and UDP-Gal, leading to bacteriostasis and bacteriolysis (33,34). On the basis of the sensitivity of galE mutants to galactose, an A. hydrophila AH-3 gene bank in pLA2917 previously obtained (35) was electroporated into S. enterica serotype Typhimurium SL1306.…”

Section: Identification and Cloning Of The A Hydrophila Ah-3 Gale Genementioning

confidence: 99%

Role of Gne and GalE in the Virulence of Aeromonas hydrophila Serotype O34

et al. 2007

View full text Add to dashboard Cite

The mesophilic Aeromonas hydrophila AH-3 (serotype O34) strain shows two different UDP-hexose epimerases in its genome: GalE (EC 3.1.5.2) and Gne (EC 3.1.5.7). Similar homologues were detected in the different mesophilic Aeromonas strains tested. GalE shows only UDP-galactose 4-epimerase activity, while Gne is able to perform a dual activity (mainly UDP-N-acetyl galactosamine 4-epimerase and also UDP-galactose 4-epimerase). We studied the activities in vitro of both epimerases and also in vivo through the lipopolysaccharide (LPS) structure of A. hydrophila gne mutants, A. hydrophila galE mutants, A. hydrophila galE-gne double mutants, and independently complemented mutants with both genes. Furthermore, the enzymatic activity in vivo, which renders different LPS structures on the mentioned A. hydrophila mutant strains or the complemented mutants, allowed us to confirm a clear relationship between the virulence of these strains and the presence/absence of the O34 antigen LPS.Mesophilic Aeromonas spp. are ubiquitous waterborne bacteria and pathogens of reptiles, amphibians, and fish (3). They can be isolated as a part of the fecal flora of a wide variety of other animals, including some used for human consumption, such a pigs, cows, sheep, and poultry. In humans, Aeromonas hydrophila isolates belonging to hybridization groups 1 and 3 (HG1 and HG3), Aeromonas veronii biovar sobria (HG8/ HG10), and Aeromonas caviae (HG4) have been associated with gastrointestinal and extraintestinal diseases, such as wound infections of healthy humans, and less commonly with septicemias of immunocompromised patients (23). The pathogenicity of mesophilic aeromonads has been linked to a number of different determinants, such as toxins, proteases, outer membrane proteins (35), lipopolysaccharide (LPS) (29), flagella (30, 37), and the type III secretion system (43).Mesophilic Aeromonas sp. strains of serotype O34 typically express smooth LPS on the surface. We fully characterized chemically the O-antigen and the core LPS of A. hydrophila strain AH-3 (serotype O34) ( Fig. 1) (24,25). Mesophilic Aeromonas strains from this serotype are the most frequently isolated in clinical sources (28). A single mutation in a gene that codes for UDP N-acetylgalactosamine 4-epimerase (gne) renders a strain with the O Ϫ phenotype (LPS without O-antigen molecules) in serotype O34 (9). No changes were observed for the LPS core in a gne mutant from strain A. hydrophila AH-3 (serotype O34). O34 antigen LPS contains N-acetyl galactosamine (GalNAc), while no such sugar residue forms part of the LPS core from A. hydrophila AH-3. The A. hydrophila AH-3 gne mutants are drastically reduced in some pathogenic features (serum resistance or adhesion to Hep-2 cells) and less virulent for fish and mice than the wild-type strain. Strain AH-3, like other mesophilic Aeromonas strains, possesses two kinds of flagella (18), and the lack of the O34-antigen molecules by the gne mutation in this strain reduced the motility without any effect on the biogenesis of both polar and ...

show abstract

Galactose-sensitive mutants of Salmonella I. Metabolism of galactose

Cited by 137 publications

References 25 publications

Control of lipopolysaccharide biosynthesis and release by Escherichia coli and Salmonella typhimurium

Control of lipopolysaccharide biosynthesis and release by Escherichia coli and Salmonella typhimurium

Porphyromonas gingivalis galEIs Involved in Lipopolysaccharide O-Antigen Synthesis and Biofilm Formation

Role of Gne and GalE in the Virulence of Aeromonas hydrophila Serotype O34

Contact Info

Product

Resources

About