MetaCyc Pathway: homospermidine biosynthesis
Inferred from experiment

Enzyme View:

Pathway diagram: homospermidine biosynthesis

This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Synonyms: polyamine biosynthesis, triaminic polyamine biosynthesis

Superclasses: BiosynthesisAmines and Polyamines Biosynthesis

Some taxa known to possess this pathway include : Nicotiana tabacum, Senecio vernalis, Senecio vulgaris

Expected Taxonomic Range: cellular organisms

sym-homospermidine is an uncommon triaminic polyamine found in bacteria, fungi, higher plants as well as amphibians, arthropods and mammalian tissues. The biosynthetic pathway has recently been worked out in higher plants with the isolation of the enzyme homospermidine synthase [Kaiser99].

The homospermidine synthase enzyme catalyzes the first biosynthetic step in pyrrolizidine alkaloids (PA) found in certain angiosperm families. homospermidine synthase detected in PA producing plants catalyzes the formation of the polyamine sym-homospermidine, the unique precursor of necine base moiety of all PA's representing 1-hydroxmethylpyrrolizidine derivatives [Frolich07].

In Nicotiana tabacum and Senecio, it has been demonstrated that the HSS enzyme evolved from deoxyhypusine synthase and possessed all the enzyme characteristics except it had lost the ability to bind elF5A [Ober99a]. The deoxyhypusine synthase enzyme however was able to carry out both sym-homospermidine as well as hypusine biosynthesis.

Created 30-Apr-2008 by Pujar A, Cornell University


Frolich07: Frolich C, Ober D, Hartmann T (2007). "Tissue distribution, core biosynthesis and diversification of pyrrolizidine alkaloids of the lycopsamine type in three Boraginaceae species." Phytochemistry 68(7);1026-37. PMID: 17320124

Kaiser99: Kaiser A (1999). "Cloning and expression of a cDNA encoding homospermidine synthase from Senecio vulgaris (Asteraceae) in Escherichia coli." Plant J 19(2);195-201. PMID: 10476066

Ober99: Ober D, Hartmann T (1999). "Homospermidine synthase, the first pathway-specific enzyme of pyrrolizidine alkaloid biosynthesis, evolved from deoxyhypusine synthase." Proc Natl Acad Sci U S A 96(26);14777-82. PMID: 10611289

Ober99a: Ober D, Hartmann T (1999). "Deoxyhypusine synthase from tobacco. cDNA isolation, characterization, and bacterial expression of an enzyme with extended substrate specificity." J Biol Chem 274(45);32040-7. PMID: 10542236

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Thu May 5, 2016, biocyc14.