Glutamine utilization by Rhizobium etli.
We undertook the study of the use of glutamine (Gln) as the source of carbon and energy by Rhizobium etli. Tn5-induced mutagenesis allowed us to identify several genes required for Gln utilization, including those coding for two broad-range amino acid transporters and a glutamate dehydrogenase. The isolated mutants were characterized by the analysis of their capacity i) to grow on different media, ii) to transport Gln (uptake assays), and iii) to utilize Gln as the C energy source (CO2 production from Gln). We show that Gln is degraded through the citric acid cycle and that its utilization as the sole C source is related to a change in the bacterial cell shape (from bacillary to coccoid form) and a high susceptibility to a thiol oxidative insult. Both these data and the analysis of ntr-dependent promoters suggested that Gln-grown bacteria are under a condition of C starvation and N sufficiency, and as expected, the addition of glucose counteracted the morphological change and increased both the bacterial growth rate and their resistance to oxidative stress. Finally, a nodulation analysis indicates that the genes involved in Gln transport and degradation are dispensable for the bacterial ability to induce and invade developing nodules, whereas those involved in gluconeogenesis and nucleotide biosynthesis are strictly required.
Tatè
Rosarita
R
Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Via G. Marconi 10, 80125 Naples, Italy.
Ferraioli
Simona
S
Filosa
Stefania
S
Cermola
Michele
M
Riccio
Anna
A
Iaccarino
Maurizio
M
Patriarca
Eduardo J
EJ
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002245:Carbon Dioxide / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D005969:Glutamate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D018384:Oxidative Stress; D042163:Rhizobium etli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013559:Symbiosis / Q000187:drug effects / Q000502:physiology
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; C037853:glutamine transport proteins; D005973:Glutamine; D002245:Carbon Dioxide; D005969:Glutamate Dehydrogenase; D005947:Glucose; D009584:Nitrogen