ISSN:
1432-072X
Keywords:
Key words Bradyrhizobium japonicum
;
Heat shock
;
DegP
;
HtrA
;
Periplasmic serine protease
;
Small
;
heat-shock protein
;
Mutants
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract A degP (htrA)-like gene of Bradyrhizobium japonicum was identified immediately downstream of two genes (hspB and hspC) coding for small heat-shock proteins. All three genes are oriented in the same direction and are separated by only 85 and 72 bp, and a heat-inducible transcript covering hspB, hspC, and degP was detected by RT-PCR. These results show that the genes are organized in an operon. Two mutants, a degP insertion mutant and a ΔhspBCdegP mutant, were constructed by marker replacement mutagenesis. Immunoblot analysis performed with a serum raised against the amino-terminal end of IbpA, an HspB homolog of Escherichia coli, identified three heat-inducible protein bands in B. japonicum extract, one of which was missing in the deletion mutant. None of the mutants showed an obvious defect during growth at different temperatures, after heat-shock treatment, or in the presence of solvents. Moreover, they were not affected in root-nodule symbiosis, indicating that the small heat-shock proteins HspB and HspC and the DegP homolog of B. japonicum are not required under a wide range of growth conditions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002030050547
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