The ancient roots of nicotianamine: diversity, role, regulation and evolution of nicotianamine-like metallophores
Abstract
Nicotianamine(NA)isametabolitesynthesized by allplantsinwhichitisinvolved inthe
homeostasisofdifferentmicronutrientssuchasiron,nickelorzinc.Insomeplantsitalso
serves as a precursor of phytosiderophores that are used for extracellular iron
scavenging.PreviousworkshavealsoestablishedthepresenceofNA infilamentousfungi
andsomemosseswhereasananalogueofNAwasinferredinanarchaea.Morerecently,
opine-typemetallophoreswithhomologytoNAwereuncoveredinbacteria, especiallyin
human pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa or Yersinia
pestis, synthesizing respectively staphylopine, pseudopalineand yersinopine.Here, we
reviewthecurrentstateofknowledgeregardingthediscovery,biosynthesis,functionand
regulationofthesemetallophores.WealsodiscussthegenomicenvironmentofthecntL
gene,whichishomologous totheplantNAsynthase(NAS)gene,andplaysacentralrole
inthesynthesisofNA-like metallophores.Thisreveals alargediversityofbiosynthetic,
export and import pathways.Using sequence similarity networks, we uncovered that
these metallophores are widespread in numerous bacteria thriving in very different
environments,suchasthose livingatthehost-pathogeninterfacebutalsointhe soil. We
additionally establishedaphylogenyoftheNAS/cntLgeneand,asaresult,wepropose
thatthisgene isanancientgeneandNA, oritsderivatives, isan ancientmetallophore that
playedaprominentroleinmetalacquisition ormetalresistance.Indeed,ourphylogenetic
analysis suggests an evolutionary model where the possibility to synthesize this
metallophore waspresentearlyintheapparitionoflife, althoughit waslaterlostbymost
living microorganisms, unless facing metal starvation such as at the host-pathogen
interface or in some soils. According to our model, NA then re-emerged as a central
metabolitefor metalhomeostasis in fungi,mossesandallknownhigherplants.
Origin : Files produced by the author(s)