scholarly journals Biochemical characterization of polypeptides encoded by mutated human Ha-ras1 genes.

1986 ◽  
Vol 6 (2) ◽  
pp. 730-734 ◽  
Author(s):  
W W Colby ◽  
J S Hayflick ◽  
S G Clark ◽  
A D Levinson
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Kinase Activity ◽  
Biochemical Characterization ◽  
Strong Support ◽  
Guanine Nucleotides ◽  
Amino Acid Substitutions ◽  
Gtpase Activity ◽  
P21 Ras

We expressed six forms of p21-ras polypeptides in Escherichia coli with differing transformation potentials resulting from amino acid substitutions at position 12. The ability of the encoded p21's to autophosphorylate, bind guanine nucleotides, and hydrolyze GTP was assessed. All versions of p21 bound GTP equivalently; the kinase activity, while dependent upon residue 12, did not correlate with the transforming potential of the polypeptide. All transforming versions exhibited an impaired GTPase activity, while a novel nontransforming derivative [p21(pro-12)] possessed an enhanced GTPase activity. These results provide strong support for the proposal that an impairment of the cellular p21 GTPase activity can unmask its transforming potential.

Biochemical characterization of polypeptides encoded by mutated human Ha-ras1 genes

1986 ◽  
Vol 6 (2) ◽  
pp. 730-734
Author(s):  
W W Colby ◽  
J S Hayflick ◽  
S G Clark ◽  
A D Levinson
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Kinase Activity ◽  
Biochemical Characterization ◽  
Strong Support ◽  
Guanine Nucleotides ◽  
Amino Acid Substitutions ◽  
Gtpase Activity ◽  
P21 Ras

We expressed six forms of p21-ras polypeptides in Escherichia coli with differing transformation potentials resulting from amino acid substitutions at position 12. The ability of the encoded p21's to autophosphorylate, bind guanine nucleotides, and hydrolyze GTP was assessed. All versions of p21 bound GTP equivalently; the kinase activity, while dependent upon residue 12, did not correlate with the transforming potential of the polypeptide. All transforming versions exhibited an impaired GTPase activity, while a novel nontransforming derivative [p21(pro-12)] possessed an enhanced GTPase activity. These results provide strong support for the proposal that an impairment of the cellular p21 GTPase activity can unmask its transforming potential.

scholarly journals TEM-109 (CMT-5), a Natural Complex Mutant of TEM-1 β-Lactamase Combining the Amino Acid Substitutions of TEM-6 and TEM-33 (IRT-5)

2005 ◽  
Vol 49 (11) ◽  
pp. 4443-4447 ◽  
Author(s):  
F. Robin ◽  
J. Delmas ◽  
C. Chanal ◽  
D. Sirot ◽  
J. Sirot ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Protein Sequence ◽  
Hydrolytic Activity ◽  
Conjugative Plasmid ◽  
Amino Acid Substitutions ◽  
Resistance Phenotype ◽  
Natural Complex ◽  
Synergy Test

ABSTRACT Escherichia coli CF349 exhibited a complex β-lactam resistance phenotype, including resistance to amoxicillin and ticarcillin alone and in combination with clavulanate and to some extended-spectrum cephalosporins. The double-disk synergy test was positive. CF349 harbored an 85-kb conjugative plasmid which encoded a β-lactamase of pI 5.9. The corresponding bla gene was identified by PCR and sequencing as a bla TEM gene. The deduced protein sequence revealed a new complex mutant of TEM-1 β-lactamase designated TEM-109 (CMT-5). TEM-109 contained both the substitutions Glu104Lys and Arg164His of the expanded-spectrum β-lactamase (ESBL) TEM-6 and Met69Leu of the inhibitor-resistant TEM-33 (IRT-5). TEM-109 exhibited hydrolytic activity against ceftazidime similar to that of TEM-6 (k cat, 56 s−1 and 105 s−1, respectively; Km values, 226 and 247 μM, respectively). The 50% inhibitory concentrations of clavulanate and tazobactam (0.13 μM and 0.27 μM, respectively) were 5- to 10-fold higher for TEM-109 than for TEM-6 (0.01 and 0.06 μM, respectively) but were almost 10-fold lower than those for TEM-33. The characterization of this novel CMT, which exhibits a low level of resistance to inhibitors, highlights the emergence of this new ESBL type.

scholarly journals Characterization of Amino Acid Substitutions in KdpA, the K+-Binding and -Translocating Subunit of the KdpFABC Complex of Escherichia coli

2002 ◽  
Vol 184 (19) ◽  
pp. 5491-5494 ◽  
Author(s):  
Martin van der Laan ◽  
Michael Gaßel ◽  
Karlheinz Altendorf
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Atpase Activity ◽  
Amino Acid Substitutions ◽  
Cation Selectivity ◽  
First Time ◽  
Enzyme Complexes ◽  
Stimulation Of

ABSTRACT When grown under K+ limitation, Escherichia coli induces the K+-translocating KdpFABC complex. The stimulation of ATPase activity by NH4 + ions was shown for the first time. Substitutions in KdpA, which is responsible for K+ binding and translocation, revealed that enzyme complexes KdpA:G232A and KdpA:G232S have completely lost their cation selectivity.

scholarly journals Genetic and Biochemical Characterization of a Highly Thermostable α-l-Arabinofuranosidase fromThermobacillus xylanilyticus

2000 ◽  
Vol 66 (4) ◽  
pp. 1734-1736 ◽  
Author(s):  
Takoua Debeche ◽  
Nicola Cummings ◽  
Ian Connerton ◽  
Philippe Debeire ◽  
Michael J. O'Donohue
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Classification System ◽  
Biochemical Characterization ◽  
Glycosyl Hydrolase ◽  
Gene Encoding ◽  
Ph Range ◽  
Sequence Similarities

ABSTRACT The gene encoding an α-l-arabinofuranosidase fromThermobacillus xylanilyticus D3, AbfD3, was isolated. Characterization of the purified recombinant α-l-arabinofuranosidase produced in Escherichia coli revealed that it is highly stable with respect to both temperature (up to 90°C) and pH (stable in the pH range 4 to 12). On the basis of amino acid sequence similarities, this 56,071-Da enzyme could be assigned to family 51 of the glycosyl hydrolase classification system. However, substrate specificity analysis revealed that AbfD3, unlike the majority of F51 members, displays high activity in the presence of polysaccharides.

scholarly journals Biochemical Characterization of CPS-1, a Subclass B3 Metallo-β-Lactamase from a Chryseobacterium piscium Soil Isolate

2015 ◽  
Vol 60 (3) ◽  
pp. 1869-1873 ◽  
Author(s):  
Dereje Dadi Gudeta ◽  
Simona Pollini ◽  
Jean-Denis Docquier ◽  
Valeria Bortolaia ◽  
Gian Maria Rossolini ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Broad Spectrum ◽  
Biochemical Characterization ◽  
Amino Acid Identity ◽  
Content Type ◽  
Acid Identity ◽  
Soil Isolate

CPS-1 is a subclass B3 metallo-β-lactamase from aChryseobacteriumpisciumisolate collected from soil, showing 68% amino acid identity to the GOB-1 enzyme. CPS-1 was overproduced inEscherichia coliRosetta (DE3), purified by chromatography, and biochemically characterized. This enzyme exhibits a broad-spectrum substrate profile, including penicillins, cephalosporins, and carbapenems, which overall resembles those of L1, GOB-1, and acquired subclass B3 enzymes AIM-1 and SMB-1.

scholarly journals Amino acid substitutions and alteration in cation specificity in the melibiose carrier of Escherichia coli.

1988 ◽  
Vol 263 (28) ◽  
pp. 14276-14280 ◽  
Author(s):  
T Kawakami ◽  
Y Akizawa ◽  
T Ishikawa ◽  
T Shimamoto ◽  
M Tsuda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Substitutions
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