BacA is indispensable for successful Mesorhizobium-Astragalus symbiosis.
A homologue of Sinorhizobium meliloti bacA was isolated from Mesorhizobium huakuii 7653R, which is capable of fixing atmospheric nitrogen in symbiotic association with leguminous Astragalus sinicus (Chinese milk vetch). Inactivation of the bacA gene abolished the ability of M. huakuii 7653R to establish a successful symbiosis with its host plant. Simultaneously, compared with wild-type M. huakuii 7653R, the bacA mutant was more sensitive to cell envelope-disrupting agents (acidic solution, ethanol, SDS, and crystal violet). Mass spectrometry analysis revealed that the very-long-chain fatty acid (27-OHC-28:0 and 29-OHC-30:0) contents of lipid A was reduced in the M. huakuii 7653R bacA mutant. Taken together, our data suggest that the cell envelope was altered in the M. huakuii 7653R bacA mutant, which might deteriorate bacterial adaption to acute environmental changes encountered in host cells and ultimately result in the failure of Mesorhizobium-legume symbiosis.
National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
Xue-Juan
XJ
Tan
Yong
Y
Cheng
Yi-Xing
YX
Li
You-Guo
YG
Li
Jun-Chu
JC
Zhou
D020561:Alphaproteobacteria / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D027883:Astragalus Plant / Q000382:microbiology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry; D005227:Fatty Acids / Q000032:analysis; D015964:Gene Expression Regulation, Bacterial; D008050:Lipid A / Q000032:analysis / Q000737:chemistry; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009586:Nitrogen Fixation; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013559:Symbiosis
D001426:Bacterial Proteins; D005227:Fatty Acids; D008050:Lipid A; D026901:Membrane Transport Proteins; C082397:bacA protein, Rhizobium meliloti