Rhizobium sp. strain NGR234 possesses a remarkable number of secretion systems.
Rhizobium sp. strain NGR234 is a unique alphaproteobacterium (order Rhizobiales) that forms nitrogen-fixing nodules with more legumes than any other microsymbiont. We report here that the 3.93-Mbp chromosome (cNGR234) encodes most functions required for cellular growth. Few essential functions are encoded on the 2.43-Mbp megaplasmid (pNGR234b), and none are present on the second 0.54-Mbp symbiotic plasmid (pNGR234a). Among many striking features, the 6.9-Mbp genome encodes more different secretion systems than any other known rhizobia and probably most known bacteria. Altogether, 132 genes and proteins are linked to secretory processes. Secretion systems identified include general and export pathways, a twin arginine translocase secretion system, six type I transporter genes, one functional and one putative type III system, three type IV attachment systems, and two putative type IV conjugation pili. Type V and VI transporters were not identified, however. NGR234 also carries genes and regulatory networks linked to the metabolism of a wide range of aromatic and nonaromatic compounds. In this way, NGR234 can quickly adapt to changing environmental stimuli in soils, rhizospheres, and plants. Finally, NGR234 carries at least six loci linked to the quenching of quorum-sensing signals, as well as one gene (ngrI) that possibly encodes a novel type of autoinducer I molecule.
Biozentrum Klein Flottbek, Abteilung für Mikrobiologie und Biotechnologie, Universität Hamburg, Germany.
Christel
C
Schmeisser
Heiko
H
Liesegang
Dagmar
D
Krysciak
Nadia
N
Bakkou
Antoine
A
Le Quéré
Antje
A
Wollherr
Isabelle
I
Heinemeyer
Burkhard
B
Morgenstern
Andreas
A
Pommerening-Röser
Margarita
M
Flores
Rafael
R
Palacios
Sydney
S
Brenner
Gerhard
G
Gottschalk
Ruth A
RA
Schmitz
William J
WJ
Broughton
Xavier
X
Perret
Axel W
AW
Strittmatter
Wolfgang R
WR
Streit
D001692:Biological Transport; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D010957:Plasmids; D012231:Rhizobium / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial; D026901:Membrane Transport Proteins