scholarly journals Characterization of the Weimberg Pathway in Caulobacter crescentus

Fermentation ◽  
2018 ◽  
Vol 4 (2) ◽  
pp. 44
Author(s):  
Henrik Almqvist ◽  
Sara Jonsdottir Glaser ◽  
Celina Tufvegren ◽  
Lisa Wasserstrom ◽  
Gunnar Lidén
Keyword(s):  
Caulobacter Crescentus ◽  
Weimberg Pathway

scholarly journals Characterization of the SOS Regulon of Caulobacter crescentus

2007 ◽  
Vol 190 (4) ◽  
pp. 1209-1218 ◽  
Author(s):  
Raquel Paes da Rocha ◽  
Apuã César de Miranda Paquola ◽  
Marilis do Valle Marques ◽  
Carlos Frederico Martins Menck ◽  
Rodrigo S. Galhardo
Keyword(s):  
Dna Damage ◽  
Caulobacter Crescentus ◽  
Bacterial Species ◽  
Direct Repeat ◽  
Site Directed Mutagenesis ◽  
Dependent Manner ◽  
Wild Type ◽  
Promoter Regions ◽  
Potential Promoter

ABSTRACT The SOS regulon is a paradigm of bacterial responses to DNA damage. A wide variety of bacterial species possess homologs of lexA and recA, the central players in the regulation of the SOS circuit. Nevertheless, the genes actually regulated by the SOS have been determined only experimentally in a few bacterial species. In this work, we describe 37 genes regulated in a LexA-dependent manner in the alphaproteobacterium Caulobacter crescentus. In agreement with previous results, we have found that the direct repeat GTTCN7GTTC is the SOS operator of C. crescentus, which was confirmed by site-directed mutagenesis studies of the imuA promoter. Several potential promoter regions containing the SOS operator were identified in the genome, and the expression of the corresponding genes was analyzed for both the wild type and the lexA strain, demonstrating that the vast majority of these genes are indeed SOS regulated. Interestingly, many of these genes encode proteins with unknown functions, revealing the potential of this approach for the discovery of novel genes involved in cellular responses to DNA damage in prokaryotes, and illustrating the diversity of SOS-regulated genes among different bacterial species.

scholarly journals Characterization of highly active 2-keto-3-deoxy-L-arabinonate and 2-keto-3-deoxy-D-xylonate dehydratases in terms of the biotransformation of hemicellulose sugars to chemicals

2020 ◽  
Vol 104 (16) ◽  
pp. 7023-7035
Author(s):  
Samuel Sutiono ◽  
Bettina Siebers ◽  
Volker Sieber
Keyword(s):  
Racemic Mixture ◽  
Highly Active ◽  
Key Points ◽  
Deoxy Sugar ◽  
Weimberg Pathway ◽  
One Step ◽  
The One ◽  
Increased Activity ◽  
Enzyme Class

Abstract2-keto-3-L-arabinonate dehydratase (L-KdpD) and 2-keto-3-D-xylonate dehydratase (D-KdpD) are the third enzymes in the Weimberg pathway catalyzing the dehydration of respective 2-keto-3-deoxy sugar acids (KDP) to α-ketoglutaric semialdehyde (KGSA). The Weimberg pathway has been explored recently with respect to the synthesis of chemicals from L-arabinose and D-xylose. However, only limited work has been done toward characterizing these two enzymes. In this work, several new L-KdpDs and D-KdpDs were cloned and heterologously expressed in Escherichia coli. Following kinetic characterizations and kinetic stability studies, the L-KdpD from Cupriavidus necator (CnL-KdpD) and D-KdpD from Pseudomonas putida (PpD-KdpD) appeared to be the most promising variants from each enzyme class. Magnesium had no effect on CnL-KdpD, whereas increased activity and stability were observed for PpD-KdpD in the presence of Mg2+. Furthermore, CnL-KdpD was not inhibited in the presence of L-arabinose and L-arabinonate, whereas PpD-KdpD was inhibited with D-xylonate (I50 of 75 mM), but not with D-xylose. Both enzymes were shown to be highly active in the one-step conversions of L-KDP and D-KDP. CnL-KdpD converted > 95% of 500 mM L-KDP to KGSA in the first 2 h while PpD-KdpD converted > 90% of 500 mM D-KDP after 4 h. Both enzymes in combination were able to convert 83% of a racemic mixture of D,L-KDP (500 mM) after 4 h, with both enzymes being specific toward the respective stereoisomer. Key points• L-KdpDs and D-KdpDs are specific toward L- and D-KDP, respectively.• Mg2+affected activity and stabilities of D-KdpDs, but not of L-KdpDs.• CnL-KdpD and PpD-KdpD converted 0.5 M of each KDP isomer reaching 95 and 90% yield.• Both enzymes in combination converted 0.5 M racemic D,L-KDP reaching 83% yield.

scholarly journals Isolation and Characterization of NaCl-Sensitive Mutants of Caulobacter crescentus

2003 ◽  
Vol 69 (6) ◽  
pp. 3029-3035 ◽  
Author(s):  
Luiz Fernando G. Zuleta ◽  
Val�ria C. S. Italiani ◽  
Marilis V. Marques
Keyword(s):  
Caulobacter Crescentus ◽  
Osmotic Shock ◽  
Promoter Regions ◽  
Isolation And Characterization ◽  
Lipopolysaccharide Biosynthesis ◽  
Severe Reduction ◽  
Mutant Strains ◽  
High Concentrations ◽  
Severe Growth

ABSTRACT An attempt to characterize Caulobacter crescentus genes important for the response to high concentrations of NaCl was initiated by the isolation of mutants defective in survival in the presence of 85 mM NaCl. A transposon Tn5 library was screened, and five strains which contained different genes disrupted by the transposon were isolated. Three of the mutants had the Tn5 in genes involved in lipopolysaccharide biosynthesis, one had the Tn5 in the nhaA gene, which encodes a Na+/H+ antiporter, and one had the Tn5 in the ppiD gene, which encodes a peptidyl-prolyl cis-trans isomerase. All the mutant strains showed severe growth arrest in the presence of 85 mM NaCl, but only the nhaA mutant showed decreased viability under these conditions. All the mutants except the nhaA mutant showed a slightly reduced viability in the presence of 40 mM KCl, but all the strains showed a more severe reduction in viability in the presence of 150 mM sucrose, suggesting that they are defective in responding to osmotic shock. The promoter regions of each disrupted gene were cloned in lacZ reporter vectors, and the pattern of expression in response to NaCl and sucrose was determined; this showed that both agents induced ppiD and nhaA gene expression but did not induce the other genes. Furthermore, the ppiD gene was not induced by heat shock, indicating that it does not belong to the σ32 regulon, as opposed to what was observed for its Escherichia coli homolog.

scholarly journals Genetic analysis and characterization of a Caulobacter crescentus mutant defective in membrane biogenesis.

1984 ◽  
Vol 158 (2) ◽  
pp. 430-440
Author(s):  
D Hodgson ◽  
P Shaw ◽  
V Letts ◽  
S Henry ◽  
L Shapiro
Keyword(s):  
Genetic Analysis ◽  
Caulobacter Crescentus ◽  
Membrane Biogenesis

scholarly journals Release of Nonstop Ribosomes Is Essential

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Heather A. Feaga ◽  
Patrick H. Viollier ◽  
Kenneth C. Keiler
Keyword(s):  
Messenger Rna ◽  
Caulobacter Crescentus ◽  
Stop Codon ◽  
Selective Advantage ◽  
Gene Encoding ◽  
Content Type ◽  
Bacterial Phyla ◽  
Almost All

ABSTRACTBacterial ribosomes frequently translate to the 3′ end of an mRNA without terminating at a stop codon. Almost all bacteria use the transfer-messenger RNA (tmRNA)-basedtrans-translation pathway to release these “nonstop” ribosomes and maintain protein synthesis capacity.trans-translation is essential in some species, but in others, such asCaulobacter crescentus,trans-translation can be inactivated. To determine whytrans-translation is dispensable inC. crescentus, a Tn-seq screen was used to identify genes that specifically alter growth in cells lackingssrA, the gene encoding tmRNA. One of these genes,CC1214, was essential in ΔssrAcells. Purified CC1214 protein could release nonstop ribosomesin vitro. CC1214 is a homolog of theEscherichia coliArfB protein, and using the CC1214 sequence, ArfB homologs were identified in the majority of bacterial phyla. Most species in whichssrAhas been deleted contain an ArfB homolog, suggesting that release of nonstop ribosomes may be essential in most or all bacteria.IMPORTANCEGenes that are conserved across large phylogenetic distances are expected to confer a selective advantage. The genes required fortrans-translation,ssrAandsmpB, have been found in >99% of sequenced bacterial genomes, suggesting that they are broadly important. However, these genes can be deleted in some species without loss of viability. The identification and characterization ofC. crescentusArfB reveals whytrans-translation is not essential inC. crescentusand suggests that many other bacteria are likely to use ArfB to survive whentrans-translation is compromised.

Expression and Characterization of a GH39 β-Xylosidase II from Caulobacter crescentus

2012 ◽  
Vol 168 (8) ◽  
pp. 2218-2229 ◽  
Author(s):  
Juliana Moço Corrêa ◽  
Luciana Graciano ◽  
Josielle Abrahão ◽  
Eduardo Alexandre Loth ◽  
Rinaldo Ferreira Gandra ◽  
...  
Keyword(s):  
Caulobacter Crescentus

Biochemical characterization of Caulobacter crescentus xylose dehydrogenase

2018 ◽  
Vol 118 ◽  
pp. 1362-1367 ◽  
Author(s):  
Charles C. Lee ◽  
Douglas B. Jordan ◽  
J. Rose Stoller ◽  
Rena E. Kibblewhite ◽  
Kurt Wagschal
Keyword(s):  
Biochemical Characterization ◽  
Caulobacter Crescentus
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