Linked Life Data

7782306

Source:http://linkedlifedata.com/resource/pubmed/id/7782306

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
1995-7-17
pubmed:databankReference
pubmed:abstractText
In Escherichia coli, lysyl-tRNA synthetase activity is encoded by either a constitutive lysS gene or an inducible one, lysU. The two corresponding enzymes could be purified at homogeneity from a delta lysU and a delta lysS strain, respectively. Comparison of the pure enzymes, LysS and LysU, indicates that, in the presence of saturating substrates, LysS is about twice more active than LysU in the ATP-PPi exchange as well as in the tRNALys aminoacylation reaction. Moreover, the dissociation constant of the LysU-lysine complex is 8-fold smaller than that of the LysS-lysine complex. In agreement with this difference, the activity of LysU is less sensitive than that of LysS to the addition of cadaverine, a decarboxylation product of lysine and a competitive inhibitor of lysine binding to its synthetase. This observation points to a possible useful role of LysU, under physiological conditions causing cadaverine accumulation in the bacterium. Remarkably, these conditions also induce lysU expression. Homogeneous LysU and LysS were also compared in Ap4A synthesis. LysU is only 2-fold more active than LysS in the production of this dinucleotide. This makes unlikely that the heat-inducible LysU species could be preferentially involved in the accumulation of Ap4A inside stressed Escherichia coli cells. This conclusion could be strengthened by determining the concentrations of Ap4N (N = A, C, G, or U) in a delta lysU as well as in a lysU+ strain, before and after a 1-h temperature shift at 48 degrees C. The measured concentration values were the same in both strains.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
16
pubmed:volume
270
pubmed:geneSymbol
lysU
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14439-44
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Comparison of the enzymatic properties of the two Escherichia coli lysyl-tRNA synthetase species.
pubmed:affiliation
Laboratoire de Biochimie, URA 240 CNRS, Ecole Polytechnique, Palaiseau, France.
pubmed:publicationType
Journal Article, Comparative Study