Nourseothricin (NTC) is a member of the
streptothricin-class of
aminoglycoside antibiotics produced by ''
Streptomyces
''Streptomyces'', from στρεπτός (''streptós''), meaning "twisted", and μύκης (''múkés''), meaning "fungus", is the largest genus of Actinomycetota, and the type genus of the family Streptomycetaceae. Over 700 species of ''St ...
'' species. Chemically, NTC is a mixture of the related compounds streptothricin C, D, E, and F. NTC inhibits
protein synthesis
Protein biosynthesis, or protein synthesis, is a core biological process, occurring inside cells, balancing the loss of cellular proteins (via degradation or export) through the production of new proteins. Proteins perform a number of critica ...
by inducing miscoding. It is used as a
selection marker for a wide range of organisms including
bacteria
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
,
yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...
,
filamentous fungi, and
plant cell
Plant cells are the cells present in Viridiplantae, green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids ...
s. It is not known to have adverse side-effects on positively selected cells, a property cardinal to a selection drug.
Streptothricin F is effective against highly drug-resistant gram-negative bacteria, including
carbapenem
Carbapenems are a class of very effective antibiotic agents most commonly used for treatment of severe bacterial infections. This class of antibiotics is usually reserved for known or suspected multidrug-resistant (MDR) bacterial infections. Si ...
-resistant ''E. coli''.
NTC can be inactivated by
nourseothricin N-acetyl transferase (NAT) from ''
Streptomyces noursei'', an
enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
that
acetylates the beta-amino group of the
beta-lysine residue of NTC.
NAT can thus act as an
antibiotic resistance
Antimicrobial resistance (AMR or AR) occurs when microbes evolve mechanisms that protect them from antimicrobials, which are drugs used to treat infections. This resistance affects all classes of microbes, including bacteria (antibiotic resis ...
gene.
Properties
NTC is highly soluble in water (~ 1 g/mL) and stable in solution for 2 years at 4 °C.
NTC propertiesJena Bioscience
/ref>
References
{{Reflist
Aminoglycoside antibiotics
Eukaryotic selection compounds