scholarly journals Studies of Regulation of Expression of the Propionate (prpBCDE) Operon Provide Insights into How Salmonella typhimurium LT2 Integrates Its 1,2-Propanediol and Propionate Catabolic Pathways

1998 ◽  
Vol 180 (24) ◽  
pp. 6511-6518 ◽  
Author(s):  
Allen W. Tsang ◽  
Alexander R. Horswill ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Energy Source ◽  
Salmonella Typhimurium ◽  
Metabolic Pathway ◽  
Coenzyme A ◽  
Transcriptional Activators ◽  
Wild Type ◽  
Regulation Of Expression ◽  
Catabolic Pathways ◽  
Sigma 54 ◽  
Redundant Functions

ABSTRACT Expression of the prpBCDE operon of Salmonella typhimurium LT2 required (i) the synthesis of propionyl-coenzyme A (CoA) by the PrpE protein or the acetyl-CoA-synthesizing systems of the cell and (ii) the synthesis of 2-methylcitrate from propionyl-CoA and oxaloacetate by the PrpC protein. We propose that either 2-methylcitrate or a derivative of it signals the presence of propionate in the environment. This as yet unidentified signal is thought to serve as a coregulator of the activity of PrpR, the member of the sigma-54 family of transcriptional activators needed for activation of prpBCDE transcription. The CobB protein was also required for expression of the prpBCDE operon, but its role is less well understood. Expression of the prpBCDEoperon in cobB mutants was restored to wild-type levels upon induction of the propanediol utilization (pdu) operon by 1,2-propanediol. This effect did not require catabolism of 1,2-propanediol, suggesting that a Pdu protein, not a catabolite of 1,2-propanediol, was responsible for the observed effect. We explain the existence of these redundant functions in terms of metabolic pathway integration. In an environment with 1,2-propanediol as the sole carbon and energy source, expression of the prpBCDE operon is ensured by the Pdu protein that has CobB-like activity. Since synthesis of this Pdu protein depends on the availability of 1,2-propanediol, the cell solves the problem faced in an environment devoid of 1,2-propanediol where propionate is the sole carbon and energy source by having cobB located outside of thepdu operon and its expression independent of 1,2-propanediol. At present, it is unclear how the CobB and Pdu proteins affect prpBCDE expression.

scholarly journals Propionyl Coenzyme A Is a Common Intermediate in the 1,2-Propanediol and Propionate Catabolic Pathways Needed for Expression of the prpBCDE Operon during Growth of Salmonella enterica on 1,2-Propanediol

2003 ◽  
Vol 185 (9) ◽  
pp. 2802-2810 ◽  
Author(s):  
Sergio Palacios ◽  
Vincent J. Starai ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Salmonella Enterica ◽  
Coenzyme A ◽  
Regulatory Protein ◽  
Wild Type ◽  
Gene Encoding ◽  
Catabolic Pathways ◽  
Serovar Typhimurium ◽  
The Common ◽  
High Concentrations ◽  
Methylcitrate Synthase

ABSTRACT The studies reported here identify propionyl coenzyme A (propionyl-CoA) as the common intermediate in the 1,2-propanediol and propionate catabolic pathways of Salmonella enterica serovar Typhimurium LT2. Growth on 1,2-propanediol as a carbon and energy source led to the formation and excretion of propionate, whose activation to propionyl-CoA relied on the activities of the propionate kinase (PduW)/phosphotransacetylase (Pta) enzyme system and the CobB sirtuin-controlled acetyl-CoA and propionyl-CoA (Acs, PrpE) synthetases. The different affinities of these systems for propionate ensure sufficient synthesis of propionyl-CoA to support wild-type growth of S. enterica under low or high concentrations of propionate in the environment. These redundant systems of propionyl-CoA synthesis are needed because the prpE gene encoding the propionyl-CoA synthetase enzyme is part of the prpBCDE operon under the control of the PrpR regulatory protein, which needs 2-methylcitrate as a coactivator. Because the synthesis of 2-methylcitrate by PrpC (i.e., the 2-methylcitrate synthase enzyme) requires propionyl-CoA as a substrate, the level of propionyl-CoA needs to be raised by the Acs or PduW-Pta system before 2-methylcitrate can be synthesized and prpBCDE transcription can be activated.

scholarly journals The Drosophila engrailed and invected Genes: Partners in Regulation, Expression and Function

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 893-906 ◽  
Author(s):  
Elizabeth Gustavson ◽  
Andrew S Goldsborough ◽  
Zehra Ali ◽  
Thomas B Kornberg
Keyword(s):  
Expression Pattern ◽  
Cultured Cells ◽  
Regulatory Region ◽  
Embryonic Lethality ◽  
Wild Type ◽  
Terminal Portion ◽  
Coding Sequence ◽  
Differential Effects ◽  
And Function ◽  
Redundant Functions

Abstract We isolated and characterized numerous engrailed and invected alleles. Among the deficiencies we isolated, a mutant lacking invected sequences was viable and phenotypically normal, a mutant lacking engrailed was an embryo lethal and had slight segmentation defects, and a mutant lacking both engrailed and invected was most severely affected. In seven engrailed alleles, mutations caused translation to terminate prematurely in the central or C-terminal portion of the coding sequence, resulting in embryonic lethality and segmentation defects. Both engrailed and invected expression declined prematurely in these mutant embryos. In wild-type embryos, engrailed and invected are juxtaposed and are expressed in essentially identical patterns. A breakpoint mutant that separates the mgrailed and invected transcription units parceled different aspects of the expression pattern to engrailed or invected. We also found that both genes cause similar defects when expressed ectopically and that the protein products of both genes act to repress transcription in cultured cells. We propose that the varied phenotypes of the engrailed alleles can be explained by the differential effects these mutants have on the combination of engrailed and invected activities, that engrailed and invected share a regulatory region, and that they encode redundant functions.

scholarly journals Interaction between phosphoribosyltransferase and purified histidine tRNA from wild type Salmonella typhimurium and a derepressed hisT mutant strain

1975 ◽  
Vol 2 (4) ◽  
pp. 545-554 ◽  
Author(s):  
Roger G. Deeley ◽  
Robert F. Goldberger ◽  
John S. Kovach ◽  
Marilyn M. Meyers ◽  
Kathleen P. Mullinix
Keyword(s):  
Salmonella Typhimurium ◽  
Mutant Strain ◽  
Wild Type

scholarly journals Autoproteolysis of YscU of Yersinia pseudotuberculosis Is Important for Regulation of Expression and Secretion of Yop Proteins

2009 ◽  
Vol 191 (13) ◽  
pp. 4259-4267 ◽  
Author(s):  
Ann-Catrin Björnfot ◽  
Moa Lavander ◽  
Åke Forsberg ◽  
Hans Wolf-Watz
Keyword(s):  
Type Iii Secretion ◽  
Calcium Concentration ◽  
Wild Type Strain ◽  
Yersinia Pseudotuberculosis ◽  
Secretion System ◽  
Wild Type ◽  
Regulation Of Expression ◽  
Significant Difference ◽  
In The Wild ◽  
Needle Protein

ABSTRACT YscU of Yersinia can be autoproteolysed to generate a 10-kDa C-terminal polypeptide designated YscUCC. Autoproteolysis occurs at the conserved N↓PTH motif of YscU. The specific in-cis-generated point mutants N263A and P264A were found to be defective in proteolysis. Both mutants expressed and secreted Yop proteins (Yops) in calcium-containing medium (+Ca2+ conditions) and calcium-depleted medium (−Ca2+ conditions). The level of Yop and LcrV secretion by the N263A mutant was about 20% that of the wild-type strain, but there was no significant difference in the ratio of the different secreted Yops, including LcrV. The N263A mutant secreted LcrQ regardless of the calcium concentration in the medium, corroborating the observation that Yops were expressed and secreted in Ca2+-containing medium by the mutant. YscF, the type III secretion system (T3SS) needle protein, was secreted at elevated levels by the mutant compared to the wild type when bacteria were grown under +Ca2+ conditions. YscF secretion was induced in the mutant, as well as in the wild type, when the bacteria were incubated under −Ca2+ conditions, although the mutant secreted smaller amounts of YscF. The N263A mutant was cytotoxic for HeLa cells, demonstrating that the T3SS-mediated delivery of effectors was functional. We suggest that YscU blocks Yop release and that autoproteolysis is required to relieve this block.

scholarly journals Novobiocin Sensitivity of Salmonella typhimurium dam and/or seqA Mutants

2014 ◽  
Vol 63 (1) ◽  
pp. 51-56 ◽  
Author(s):  
ABDELWAHEB CHATTI ◽  
MERIEM ALOUI ◽  
JIHEN TAGOURTI ◽  
MOUADH MIHOUB ◽  
AHMED LANDOULSI
Keyword(s):  
Dna Methylation ◽  
Stationary Phase ◽  
Salmonella Typhimurium ◽  
The Other ◽  
Protein Profiles ◽  
Wild Type ◽  
Whole Cell ◽  
Expression Levels

This study was carried out to determine the effects of novobiocin, a gyrase inhibitor, on the growth, survival, motility and whole cell proteins of S. Typhimurium dam and/or seqA strains. Our results showed that the dam and seqA/dam mutants are the most sensitive to novobiocin, compared to wild type and seqA strains. Surprisingly, the motility of seqA mutants increased after exposure to novobiocin only in stationary phase cells. All the other strains showed a significant decrease in their motility. The analysis of protein profiles of all strains demonstrated several modifications as manifested by the alteration of the expression levels of certain bands. Our work is therefore of great interest in understanding the effects of novobiocin on S. Typhimurium and the involvement of DNA methylation.

scholarly journals Degradation of Anthracene by Mycobacterium sp. Strain LB501T Proceeds via a Novel Pathway, through o-Phthalic Acid

2003 ◽  
Vol 69 (1) ◽  
pp. 186-190 ◽  
Author(s):  
René van Herwijnen ◽  
Dirk Springael ◽  
Pieter Slot ◽  
Harrie A. J. Govers ◽  
John R. Parsons
Keyword(s):  
Energy Source ◽  
Type Strain ◽  
Phthalic Acid ◽  
Protocatechuic Acid ◽  
Wild Type Strain ◽  
Degradation Pathway ◽  
Wild Type ◽  
Catabolic Pathway ◽  
Naphthalene Degradation

ABSTRACT Mycobacterium sp. strain LB501T utilizes anthracene as a sole carbon and energy source. We analyzed cultures of the wild-type strain and of UV-generated mutants impaired in anthracene utilization for metabolites to determine the anthracene degradation pathway. Identification of metabolites by comparison with authentic standards and transient accumulation of o-phthalic acid by the wild-type strain during growth on anthracene suggest a pathway through o-phthalic acid and protocatechuic acid. As the only productive degradation pathway known so far for anthracene proceeds through 2,3-dihydroxynaphthalene and the naphthalene degradation pathway to form salicylate, this indicates the existence of a novel anthracene catabolic pathway in Mycobacterium sp. LB501T.

scholarly journals Envelope Proteins of the CsmB/CsmF and CsmC/CsmD Motif Families Influence the Size, Shape, and Composition of Chlorosomes in Chlorobaculum tepidum

2009 ◽  
Vol 191 (22) ◽  
pp. 7109-7120 ◽  
Author(s):  
Hui Li ◽  
Donald A. Bryant
Keyword(s):  
Size Composition ◽  
Envelope Proteins ◽  
Structural Motif ◽  
Supramolecular Organization ◽  
Wild Type ◽  
Absorbance Maximum ◽  
Chlorobaculum Tepidum ◽  
Mutant Strains ◽  
Redundant Functions ◽  
Mutational Study

ABSTRACT The chlorosome envelope of Chlorobaculum tepidum contains 10 proteins that belong to four structural motif families. A previous mutational study (N.-U. Frigaard, H. Li, K. J. Milks, and D. A. Bryant, J. Bacteriol. 186:646-653, 2004) suggested that some of these proteins might have redundant functions. Six multilocus mutants were constructed to test the effects of eliminating the proteins of the CsmC/CsmD and CsmB/CsmF motif families, and the resulting strains were characterized physiologically and biochemically. Mutants lacking all proteins of either motif family still assembled functional chlorosomes, and as measured by growth rates of the mutant strains, light harvesting was affected only at the lowest light intensities tested (9 and 32 μmol photons m−2 s−1). The size, composition, and biogenesis of the mutant chlorosomes differed from those of wild-type chlorosomes. Mutants lacking proteins of the CsmC/CsmD motif family produced smaller chlorosomes than did the wild type, and the Qy absorbance maximum for the bacteriochlorophyll c aggregates in these chlorosomes was strongly blueshifted. Conversely, the chlorosomes of mutants lacking proteins of the CsmB/CsmF motif family were larger than wild-type chlorosomes, and the Qy absorption for their bacteriochlorophyll c aggregates was redshifted. When CsmH was eliminated in addition to other proteins of either motif family, chlorosomes had smaller diameters. These data show that the chlorosome envelope proteins of the CsmB/CsmF and CsmC/CsmD families play important roles in determining chlorosome size as well as the assembly and supramolecular organization of the bacteriochlorophyll c aggregates within the chlorosome.

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