Evolution of the Nitric Oxide Synthase Family in Metazoans

Abstract

Nitric oxide (NO) is essential to many physiological functions and operates in several signaling pathways. It is not understood how and when the different isoforms of nitric oxide synthase (NOS), the enzyme responsible for NO production, evolved in metazoans. This study investigates the number and structure of metazoan NOS enzymes by genome data mining and direct cloning of Nos genes from the lamprey. In total, 181 NOS proteins are analyzed from 33 invertebrate and 63 vertebrate species. Comparisons among protein and gene structures, combined with phylogenetic and syntenic studies, provide novel insights into how NOS isoforms arose and diverged. Protein domains and gene organization--that is, intron positions and phases--of animal NOS are remarkably conserved across all lineages, even in fast-evolving species. Phylogenetic and syntenic analyses support the view that a proto-NOS isoform was recurrently duplicated in different lineages, acquiring new structural configurations through gains and losses of protein motifs. We propose that in vertebrates a first duplication took place after the agnathan-gnathostome split followed by a paralog loss. A second duplication occurred during early tetrapod evolution, giving rise to the three isoforms--I, II, and III--in current mammals. Overall, NOS family evolution was the result of multiple gene and genome duplication events together with changes in protein architecture.

Molecular cloning and expression pattern of oriental river prawn (Macrobrachium nipponense) nitric oxide synthase

“…Furthermore, most prior reports have confirmed the involvement of NO in metabolism, growth, cell proliferation, development, and neurogenesis in vertebrates, insects, and mollusks, verifying the broad role of NOSs in the microvascular, neural, and immune systems (Kuzin et al, 1996;Andreakis et al, 2011;Hampton et al, 2015). Furthermore, NO in rat has additional functions as it appears to be found in all parts of the male reproductive system as well and seems to play a role in testicular, epididymal and vas deferens function.…”

“…Thus, compared to vertebrate enzymes, the MnNOS sequence exhibited a relatively high level of identity with crustacean NOSs (Figure 3). This evolutionary relationship implies that, with the exception of iNOS produced by the arthropod Limulus polyphemus, different isoforms of this enzyme may not be found in invertebrates, and this lineage may have inherited only on eNOS type, as in mollusks (Andreakis et al, 2011), the mud crab Scylla paramamosain (Li et al, 2012), and the Zhikong scallop Chlamys farreri (Jiang et al, 2013). Furthermore, the observed connections between these groups might reflect taxonomic relationships, and appear to show that although MnNOS clustered with invertebrate NOS enzymes, it was not closely related to that of any species examined.…”

Nitric oxide-coupled signaling in odor elicited molecular events in the olfactory center of the terrestrial snail, Helix pomatia

“…In vertebrates, two constitutive and one inducible forms of the NOS gene have been described. In contrast, there are only a few invertebrate species, in which more than one NOS isoform has been sequenced, and in these few cases the function of the homologues have not been clearly determined [53]. In this context, the functional significance of the two NB cell populations producing different amount of NO is difficult to explain.…”

“…Alternatively, NO can directly nitrosylate specific protein cystein residues, forming S-nitrosothiols, which have a modulatory role at glutamatergic synapses, affecting synaptic vesicle release and NMDA-receptor inactivation [52]. Although NOS gene evolution and NO neurotransmitter actions have been studied intensively [53,54], the different elements of NO signaling have received little attention in invertebrates [54]. In mollusks, the canonical NO/cGMP/PKG pathway was detected in the regulation of growth cone filopodial dynamics of cultured neuron of Helisoma trivolvis [55].…”

The dynamic nitric oxide pattern in developing cuttlefish Sepia officinalis

“…NO and NOS are present in all metazoans from placozoans to vertebrates (Palumbo, 2005;Andreakis et al, 2011). Despite being a simple molecule, NO is a fundamental player in the fields of neuroscience, physiology and immunology.…”