Syntheses and stabilities of proteins related to the polyoma small T antigen in Escherichia coli

1982 ◽  
Vol 2 (1) ◽  
pp. 88-92
Author(s):  
A Horwich ◽  
A H Koop ◽  
W Eckhart
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
T Antigen ◽  
Bacterial Proteins ◽  
N Terminus ◽  
Terminal Amino ◽  
Small T Antigen ◽  
Beta Galactosidase

We compared the syntheses and turnovers of two proteins related to the polyoma small T antigen synthesized in Escherichia coli from plasmids containing polyoma genomic segments joined to lac control elements. A protein with an authentic polyoma N terminus was more unstable than a protein with N-terminal amino acids derived from beta-galactosidase. Both were more unstable than most bacterial proteins.

scholarly journals Syntheses and stabilities of proteins related to the polyoma small T antigen in Escherichia coli.

1982 ◽  
Vol 2 (1) ◽  
pp. 88-92 ◽  
Author(s):  
A Horwich ◽  
A H Koop ◽  
W Eckhart
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
T Antigen ◽  
Bacterial Proteins ◽  
N Terminus ◽  
Terminal Amino ◽  
Small T Antigen ◽  
Beta Galactosidase

We compared the syntheses and turnovers of two proteins related to the polyoma small T antigen synthesized in Escherichia coli from plasmids containing polyoma genomic segments joined to lac control elements. A protein with an authentic polyoma N terminus was more unstable than a protein with N-terminal amino acids derived from beta-galactosidase. Both were more unstable than most bacterial proteins.

scholarly journals Roles of the C-Terminal Amino Acids of Non-Hexameric Helicases: Insights from Escherichia coli UvrD

2021 ◽  
Vol 22 (3) ◽  
pp. 1018
Author(s):  
Hiroaki Yokota
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Single Molecule ◽  
Underlying Mechanism ◽  
Amino Acid Sequences ◽  
E Coli ◽  
X Ray Crystallography ◽  
Terminal Amino

Helicases are nucleic acid-unwinding enzymes that are involved in the maintenance of genome integrity. Several parts of the amino acid sequences of helicases are very similar, and these quite well-conserved amino acid sequences are termed “helicase motifs”. Previous studies by X-ray crystallography and single-molecule measurements have suggested a common underlying mechanism for their function. These studies indicate the role of the helicase motifs in unwinding nucleic acids. In contrast, the sequence and length of the C-terminal amino acids of helicases are highly variable. In this paper, I review past and recent studies that proposed helicase mechanisms and studies that investigated the roles of the C-terminal amino acids on helicase and dimerization activities, primarily on the non-hexermeric Escherichia coli (E. coli) UvrD helicase. Then, I center on my recent study of single-molecule direct visualization of a UvrD mutant lacking the C-terminal 40 amino acids (UvrDΔ40C) used in studies proposing the monomer helicase model. The study demonstrated that multiple UvrDΔ40C molecules jointly participated in DNA unwinding, presumably by forming an oligomer. Thus, the single-molecule observation addressed how the C-terminal amino acids affect the number of helicases bound to DNA, oligomerization, and unwinding activity, which can be applied to other helicases.

Complementation of a polyamine-deficient Escherichia coli mutant by expression of mouse ornithine decarboxylase

1987 ◽  
Vol 7 (1) ◽  
pp. 564-567
Author(s):  
M Macrae ◽  
P Coffino
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Enzymatic Activity ◽  
Ornithine Decarboxylase ◽  
Polyamine Biosynthesis ◽  
Coli Mutant ◽  
Terminal Amino ◽  
High Level ◽  
Carboxy Terminal ◽  
Exogenous Source

Mouse ornithine decarboxylase (ODCase) cDNA was expressed at a high level in an Escherichia coli mutant deficient in polyamine biosynthesis. The expression of mouse ornithine decarboxylase relieved the dependence of the mutant on an exogenous source of polyamines, presumably by providing putrescine, the product of the enzyme. The effect on the enzymatic activity of deletions that removed carboxy-terminal amino acids of the protein was determined.

scholarly journals Altered affinity of insulin-like growth factor II (IGF-II) for receptors and IGF-binding proteins, resulting from limited modifications of the IGF-II molecule

1991 ◽  
Vol 278 (1) ◽  
pp. 249-254 ◽  
Author(s):  
Y Oh ◽  
M W Beukers ◽  
H M Pham ◽  
P A Smanik ◽  
M C Smith ◽  
...  
Keyword(s):  
Amino Acids ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Type I ◽  
Type Ii ◽  
Factor Ii ◽  
N Terminus ◽  
Severe Impairment ◽  
Igf Binding ◽  
Terminal Amino

The binding affinities of seven analogues of recombinant human insulin-like growth factor II (hIGF-II) were characterized for the IGF type-I and type-II receptors and insulin receptors, as well as for IGF-binding protein (IGFBP)-1, IGFBP-2, IGFPB-3 and human serum IGFBPs. A switch of two of the three cysteine bridges in hIGF-II, 9-47 and 46-51 to 9-46 and 47-51, severely impaired the binding of this analogue to all receptors and to the IGFBPs. The affinities for the IGF type-I receptor and the IGFBPs were decreased over 100-fold, while the binding to the insulin receptor and the IGF type-II receptor was less affected, with a 6-10-fold decrease in affinity. Slight modifications of the N-terminus had only minor effects upon the binding of hIGF-II to the IGFBPs or to the receptors. Deletion of both the N-terminal amino acid and the two C-terminal amino acids resulted in moderate decreases in affinity, with a 60% decrease in affinity for IGFBP-1 and the IGF type-I receptor. Acetylation of the N-terminus of Ala1 and the epsilon-nitrogen of Lys65 decreased the affinity, by 60-90%, of hIGF-II for all of the IGFBPs and receptors. The experiments involving acetylation of IGF-II or switching of its cysteine bridges indicated that these modifications (no substitution, deletion or addition of any of the 67 amino acids of hIGF-II) may lead to a severe impairment of the binding affinity of IGF-II for both the IGFBPs and the receptors. Acetylation of the epsilon-nitrogen of Lys65, which causes a charge change, or alteration of the three-dimensional structure, as shown by the cysteine bridge switch, lead to a severe impairment of the binding affinity for the binding proteins and for the receptors. In general, care should be taken with the synthesis of analogues and the interpretation of resulting binding data, since affinity alterations ascribed to amino acid changes may instead be caused by alterations of the charge or the three-dimensional structure of the protein.

scholarly journals Escherichia coli l-aspartate-α-decarboxylase: preprotein processing and observation of reaction intermediates by electrospray mass spectrometry

1997 ◽  
Vol 323 (3) ◽  
pp. 661-669 ◽  
Author(s):  
Manoj K. RAMJEE ◽  
Ulrich GENSCHEL ◽  
Chris ABELL ◽  
Alison G. SMITH
Keyword(s):  
Mass Spectrometry ◽  
Escherichia Coli ◽  
Electrospray Mass Spectrometry ◽  
Elevated Temperatures ◽  
Gene Encoding ◽  
Α Subunit ◽  
C Terminus ◽  
N Terminus ◽  
Terminal Amino ◽  
Α Subunits

The Escherichia coli panD gene, encoding l-aspartate-α-decarboxylase, was cloned by PCR, and shown to complement apanD mutant defective in β-alanine biosynthesis. Aspartate decarboxylase is a pyruvoyl-dependent enzyme, and is synthesized initially as an inactive proenzyme (the π-protein), which is proteolytically cleaved at a specific X–Ser bond to produce a β-subunit with XOH at its C-terminus and an α-subunit with a pyruvoyl group at its N-terminus, derived from the serine. The recombinant enzyme, as purified, is a tetramer, and comprises principally the unprocessed π-subunit (of 13.8 kDa), with a small proportion of the α- and β-subunits (11 kDa and 2.8 kDa respectively). Incubation of the purified enzyme at elevated temperatures for several hours results in further processing. Using fluorescein thiosemicarbazide, the completely processed enzyme was shown to contain three pyruvoyl groups per tetrameric enzyme. The presence of unchanged serine at the N-terminus of some of the α-subunits was confirmed by electrospray mass spectrometry (ESMS) and N-terminal amino acid sequencing. A novel HPLC assay for aspartate decarboxylase was established and used to determine the Km and kcat for l-aspartate as 151±16 μM and 0.57 s-1 respectively. ESMS was also used to observe substrate and product adducts trapped on the pyruvoyl group by sodium cyanoborohydride treatment.

scholarly journals Kinetics and mechanism of the bactericidal action of human neutrophils against Escherichia coli

Blood ◽  
1984 ◽  
Vol 64 (3) ◽  
pp. 635-641
Author(s):  
MN Hamers ◽  
AA Bot ◽  
RS Weening ◽  
HJ Sips ◽  
D Roos
Keyword(s):  
Escherichia Coli ◽  
Computer Program ◽  
Rate Constants ◽  
Bacterial Cell ◽  
Cell Envelope ◽  
Human Neutrophils ◽  
Galactosidase Activity ◽  
E Coli ◽  
Bacterial Proteins ◽  
Beta Galactosidase

A mutant strain of Escherichia coli (E. coli ML-35) was used to follow the kinetics of phagocytosis, perforation of the bacterial cell envelope, and inactivation of bacterial proteins by human neutrophils. This particular E. coli mutant strain has no lactose permease, but constitutively forms the cytoplasmic enzyme beta-galactosidase. This implies that the artificial substrate ortho-nitrophenyl-beta-D- galactopyranoside cannot reach the beta-galactosidase unless the bacterial cell envelope has been perforated. Thus, the integrity of the E. coli envelope can be measured simply by the activity of beta- galactosidase with this substrate. Indeed, ingestion of E. coli ML-35 by human neutrophils was followed by perforation of the bacteria (increase in beta-galactosidase activity). Subsequently, the beta- galactosidase activity decreased due to inactivation of the enzyme. With a simple mathematical model and a curve-fitting computer program, we have determined the first-order rate constants for phagocytosis, perforation, and beta-galactosidase inactivation. With 32 normal donors, we found an interdonor variation in these rate constants of 20% to 30% (SD) and an assay variance of 5%. The perforation process closely correlated with the loss of colony-forming capacity of the bacteria. This new assay measures phagocytosis and killing in a fast, simple, and accurate way; it is not hindered by extracellular bacteria. Moreover, this method also measures the postkilling event of inactivation of a bacterial protein, which permits a better detection of neutrophils deficient in this function. The assay can also be used for screening neutrophil functions without the use of a computer program. A simple calculation suffices to detect neutrophil abnormalities. Neutrophils from patients with chronic granulomatous disease (CGD) showed an impaired rate of perforation and thus also of inactivation. Neutrophils from myeloperoxidase-deficient patients or from a patient with the Chediak-Higashi syndrome only showed a retarded inactivation of beta-galactosidase, but normal ingestion and perforation. The role of myeloperoxidase in the killing process is discussed. Although myeloperoxidase does not seem to be a prerequisite for perforation, it probably plays a role in bacterial destruction by normal cells, because the inactivation of bacterial proteins seems strictly myeloperoxidase dependent.

Amino acid sequences that determine the nuclear localization of yeast histone 2B

1987 ◽  
Vol 7 (11) ◽  
pp. 4048-4057
Author(s):  
R B Moreland ◽  
G L Langevin ◽  
R H Singer ◽  
R L Garcea ◽  
L M Hereford
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Fusion Protein ◽  
Point Mutation ◽  
Nuclear Localization ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Amino Acid Sequences ◽  
Nuclear Localization Sequence ◽  
Beta Galactosidase

Histone-beta-galactosidase protein fusions were used to identify the domain of yeast histone 2B, which targets this protein to the nucleus. Amino acids 28 to 33 in H2B were required for nuclear localization of such fusion proteins and thus constitute a nuclear localization sequence. The amino acid sequence in this region (Gly-29 Lys Lys Arg Ser Lys Ala) is similar to the nuclear location signal in simian virus 40 large T antigen (Pro-126 Lys Lys Lys Arg Lys Val) (D. Kalderon, B.L. Roberts, W.D. Richardson, and A.E. Smith, Cell 39:499-509, 1984). A point mutation changing lysine 31 to methionine abolished nuclear localization of an H2B-beta-galactosidase fusion protein containing amino acids 1 to 33 of H2B. However, an H2B-beta-galactosidase fusion protein containing both this point mutation and the H2A interaction domain of H2B was nuclear localized. These results suggest that H2A and H2B may be cotransported to the nucleus as a heterodimer.

scholarly journals Kinetics and mechanism of the bactericidal action of human neutrophils against Escherichia coli

Blood ◽  
1984 ◽  
Vol 64 (3) ◽  
pp. 635-641 ◽  
Author(s):  
MN Hamers ◽  
AA Bot ◽  
RS Weening ◽  
HJ Sips ◽  
D Roos
Keyword(s):  
Escherichia Coli ◽  
Computer Program ◽  
Rate Constants ◽  
Bacterial Cell ◽  
Cell Envelope ◽  
Human Neutrophils ◽  
Galactosidase Activity ◽  
E Coli ◽  
Bacterial Proteins ◽  
Beta Galactosidase

Abstract A mutant strain of Escherichia coli (E. coli ML-35) was used to follow the kinetics of phagocytosis, perforation of the bacterial cell envelope, and inactivation of bacterial proteins by human neutrophils. This particular E. coli mutant strain has no lactose permease, but constitutively forms the cytoplasmic enzyme beta-galactosidase. This implies that the artificial substrate ortho-nitrophenyl-beta-D- galactopyranoside cannot reach the beta-galactosidase unless the bacterial cell envelope has been perforated. Thus, the integrity of the E. coli envelope can be measured simply by the activity of beta- galactosidase with this substrate. Indeed, ingestion of E. coli ML-35 by human neutrophils was followed by perforation of the bacteria (increase in beta-galactosidase activity). Subsequently, the beta- galactosidase activity decreased due to inactivation of the enzyme. With a simple mathematical model and a curve-fitting computer program, we have determined the first-order rate constants for phagocytosis, perforation, and beta-galactosidase inactivation. With 32 normal donors, we found an interdonor variation in these rate constants of 20% to 30% (SD) and an assay variance of 5%. The perforation process closely correlated with the loss of colony-forming capacity of the bacteria. This new assay measures phagocytosis and killing in a fast, simple, and accurate way; it is not hindered by extracellular bacteria. Moreover, this method also measures the postkilling event of inactivation of a bacterial protein, which permits a better detection of neutrophils deficient in this function. The assay can also be used for screening neutrophil functions without the use of a computer program. A simple calculation suffices to detect neutrophil abnormalities. Neutrophils from patients with chronic granulomatous disease (CGD) showed an impaired rate of perforation and thus also of inactivation. Neutrophils from myeloperoxidase-deficient patients or from a patient with the Chediak-Higashi syndrome only showed a retarded inactivation of beta-galactosidase, but normal ingestion and perforation. The role of myeloperoxidase in the killing process is discussed. Although myeloperoxidase does not seem to be a prerequisite for perforation, it probably plays a role in bacterial destruction by normal cells, because the inactivation of bacterial proteins seems strictly myeloperoxidase dependent.

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