Table 3.

Presence of genes encoding enzymes of the L-arginine-degrading pathways in the genomes of selected marine and freshwater cyanobacteria.

Pathway	L-Arginine decarboxylase
Enzymes	A1	A2.1	A2.2	A2.3	A3	A4	A5	A6
Marine species
Prochlorococcus marinus SS 120	+	+	n.d.	+	n.d.	+	+	+
Prochlorococcus marinus str. MIT 9211	+	+	n.d.	+	n.d.	+	+	+
Prochlorococcus marinus MIT 9312	+	+	n.d.	+	n.d.	+	+	+
Prochlorococcus marinus MIT 9313	+	+	n.d.	+	n.d.	+	+	+
Prochlorococcus marinus MED 4	+	+	n.d.	+	n.d.	+	+	+
Prochlorococcus marinus NATL 2A	+	+	n.d.	+	n.d.	+	+	+
Synechococcus sp. CC 9605	+	+	n.d.	+	n.d.	+	+	+
Synechococcus sp. CC 9902	+	+	n.d.	+	n.d.	+	+	+
Synechococcus sp. WH 8102	+	+	n.d.	+	n.d.	+	+	+
Synechococcus sp. WH 7805	+	+	n.d.	+	n.d.	n.d.	+	+
Synechococcus sp. WH 5701	+	+	n.d.	+	n.d.	+	+	+
Synechococcus sp. RS 9917	+	+	n.d.	+	n.d.	+	+	+
Crocosphaera watsonii WH 8501	+	n.d.	n.d.	+	n.d.	+	+	+
Trichodesmium erythraeum IMS 101	+	+	n.d.	+	n.d.	+	+	+
Freshwater species
Synechococcus elongatus sp. PCC 6301	+	n.d.	+	+	n.d.	+	+	+
Synechococcus elongatus sp. PCC 7942	+	n.d.	+	+	n.d.	+	+	+
Synechococcus Yellowstone sp. A JA-3-3-AB	+	+	n.d.	+	n.d.	+	+	+
Synechococcus Yellowstone sp. B JA-2-3B'a (2–13)	+	+	n.d.	+	n.d.	+	+	+
Thermosynechococcus elongatus BP-1	+	n.d.	+	+	n.d.	+	+	+
Synechocystis sp. PCC 6803	+	+	n.d.	+	n.d.	+	+	+
Gloeobacter violaceus PCC 7421	+	n.d.	+	+	n.d.	+	+	+
Nostoc sp. PCC 7120	+	+	n.d.	+	n.d.	+	+	+
Nostoc punctiforme PCC 73102	+	+	n.d.	+	n.d.	+	+	+
Anabaena variabilis ATCC 29413	+	+	n.d.	+	n.d.	+	+	+

L-ornithine is formed from L-arginine by the enzymes arginase or L-arginine amidinotransferase. It is also formed in the 2^nd reaction of the L-arginine deiminase pathway. Enzymes A5 and E3 are identical enzymes and both represent a 4-aminobutyrate transaminase. Enzymes A6 and E4 are identical and both represent a succinate semialdehyde dehydrogenase (Fig. 2). Enzymes A2.1, B1, and C1 represent ureohydrolases, and the same gene(s) is (are) annotated as an agmatinase (A2.1), an arginase (B1) or a 4-guanidinobutyrase (E2). The genes encoding the enzymes C1 and D1 are annotated as L-arginine amidinotransferase as well as L-arginine deiminase (see text for further details). N.d. = not detected.