A 70-amino acid zinc-binding polypeptide from the regulatory chain of aspartate transcarbamoylase forms a stable complex with the catalytic subunit leading to markedly altered enzyme activity.

Background: Nε-acetyl L-α lysine is an unusual acetylated di-amino acid synthesized and accumulated by certain halophiles under osmotic stress. Osmolytes are generally known to protect proteins and other cellular components under various stress conditions. Objective: The structural and functional stability imparted by Nε-acetyl L-lysine on proteins were unknown and hence was studied and compared to other commonly known bacterial osmolytes - ectoine, proline, glycine betaine, trehalose and sucrose. Methods: Effects of osmolytes on the temperature and pH profiles, pH stability and thermodynamic stability of the model enzyme, α-amylase were analyzed. Results: At physiological pH, all the osmolytes under study increased the optimal temperature for enzyme activity and improved the thermodynamic stability of the enzyme. At acidic conditions (pH 3.0), Nε-acetyl L-α lysine and ectoine improved both the catalytic and thermodynamic stability of the enzyme; it was reflected in the increase in residual enzyme activity after incubation of the enzyme at pH 3.0 for 15 min by 60% and 63.5% and the midpoint temperature of unfolding transition by 11°C and 10°C respectively. Conclusion: Such significant protective effects on both activity and stability of α-amylase imparted by addition of Nε-acetyl L-α lysine and ectoine at acidic conditions make these osmolytes interesting candidates for biotechnological applications.

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The methyltransferase METTL9 mediates pervasive 1-methylhistidine modification in mammalian proteomes

Nature Communications ◽

10.1038/s41467-020-20670-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Erna Davydova ◽

Tadahiro Shimazu ◽

Maren Kirstin Schuhmacher ◽

Magnus E. Jakobsson ◽

Hanneke L. D. M. Willemen ◽

...

Keyword(s):

Amino Acid ◽

Protein Function ◽

Crucial Role ◽

Complex I ◽

Protein Modification ◽

Zinc Binding ◽

Functional Studies ◽

Mitochondrial Respiratory Complex ◽

Respiratory Complex I ◽

Broad Specificity

AbstractPost-translational methylation plays a crucial role in regulating and optimizing protein function. Protein histidine methylation, occurring as the two isomers 1- and 3-methylhistidine (1MH and 3MH), was first reported five decades ago, but remains largely unexplored. Here we report that METTL9 is a broad-specificity methyltransferase that mediates the formation of the majority of 1MH present in mouse and human proteomes. METTL9-catalyzed methylation requires a His-x-His (HxH) motif, where “x” is preferably a small amino acid, allowing METTL9 to methylate a number of HxH-containing proteins, including the immunomodulatory protein S100A9 and the NDUFB3 subunit of mitochondrial respiratory Complex I. Notably, METTL9-mediated methylation enhances respiration via Complex I, and the presence of 1MH in an HxH-containing peptide reduced its zinc binding affinity. Our results establish METTL9-mediated 1MH as a pervasive protein modification, thus setting the stage for further functional studies on protein histidine methylation.

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Human endothelin receptor ETB. Amino acid sequence requirements for super stable complex formation with its ligand.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)37315-5 ◽

1994 ◽

Vol 269 (10) ◽

pp. 7509-7513

Author(s):

T. Takasuka ◽

T. Sakurai ◽

K. Goto ◽

Y. Furuichi ◽

T. Watanabe

Keyword(s):

Amino Acid ◽

Complex Formation ◽

Amino Acid Sequence ◽

Stable Complex ◽

Endothelin Receptor ◽

Sequence Requirements

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Primary structure requirements for correct sorting of the yeast mitochondrial protein ADH III to the yeast mitochondrial matrix space.

Molecular and Cellular Biology ◽

10.1128/mcb.7.1.294 ◽

1987 ◽

Vol 7 (1) ◽

pp. 294-304 ◽

Cited By ~ 30

Author(s):

D Pilgrim ◽

E T Young

Keyword(s):

Amino Acids ◽

Enzyme Activity ◽

Amino Acid ◽

Proteolytic Processing ◽

Mitochondrial Matrix ◽

Wild Type ◽

Mature Form ◽

Amino Terminal ◽

The Matrix

Alcohol dehydrogenase isoenzyme III (ADH III) in Saccharomyces cerevisiae, the product of the ADH3 gene, is located in the mitochondrial matrix. The ADH III protein was synthesized as a larger precursor in vitro when the gene was transcribed with the SP6 promoter and translated with a reticulocyte lysate. A precursor of the same size was detected when radioactively pulse-labeled proteins were immunoprecipitated with anti-ADH antibody. This precursor was rapidly processed to the mature form in vivo with a half-time of less than 3 min. The processing was blocked if the mitochondria were uncoupled with carbonyl cyanide m-chlorophenylhydrazone. Mutant enzymes in which only the amino-terminal 14 or 16 amino acids of the presequence were retained were correctly targeted and imported into the matrix. A mutant enzyme that was missing the amino-terminal 17 amino acids of the presequence produced an active enzyme, but the majority of the enzyme activity remained in the cytoplasmic compartment on cellular fractionation. Random amino acid changes were produced in the wild-type presequence by bisulfite mutagenesis of the ADH3 gene. The resulting ADH III protein was targeted to the mitochondria and imported into the matrix in all of the mutants tested, as judged by enzyme activity. Mutants containing amino acid changes in the carboxyl-proximal half of the ADH3 presequence were imported and processed to the mature form at a slower rate than the wild type, as judged by pulse-chase studies in vivo. The unprocessed precursor appeared to be unstable in vivo. It was concluded that only a small portion of the presequence contains the necessary information for correct targeting and import. Furthermore, the information for correct proteolytic processing of the presequence appears to be distinct from the targeting information and may involve secondary structure information in the presequence.

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