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A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans

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ABSTRACT

The translocation and assembly module (TAM) in bacteria consists of TamA and TamB that form a complex to control the transport and secretion of outer membrane proteins. Herein, we demonstrated that the DR_1462-DR_1461-DR_1460 gene loci on chromosome 1 of Deinococcus radiodurans, which lacks tamA homologs, is a tamB homolog (DR_146T) with two tamB motifs and a DUF490 motif. Mutation of DR_146T resulted in cell envelope peeling and a decrease in resistance to shear stress and osmotic pressure, as well as an increase in oxidative stress resistance, consistent with the phenotype of a surface layer (S-layer) protein SlpA (DR_2577) mutant, demonstrating the involvement of DR_146T in maintenance of cell envelope integrity. The 123 kDa SlpA was absent and only its fragments were present in the cell envelope of DR_146T mutant, suggesting that DR_146T might be involved in maintenance of the S-layer. A mutant lacking the DUF490 motif displayed only a slight alteration in phenotype compared with the wild type, suggesting DUF490 is less important than tamB motif for the function of DR_146T. These findings enhance our understanding of the properties of the multilayered envelope in extremophilic D. radiodurans, as well as the diversity and functions of TAMs in bacteria.

No MeSH data available.


Survival of D. radiodurans wild type and mutant strains to shear stress.The survival fraction of ∆DR_146T was substantially lower than that for the wild type and ∆DR_146T-DUF490 under shear stress. DRWT, D. radiodurans wild type; ∆DR_146T-DUF490, mutant deficient in the DUF490 motif of DR_146T; ∆DR_146T, mutant deficient in DR_146T.
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f4: Survival of D. radiodurans wild type and mutant strains to shear stress.The survival fraction of ∆DR_146T was substantially lower than that for the wild type and ∆DR_146T-DUF490 under shear stress. DRWT, D. radiodurans wild type; ∆DR_146T-DUF490, mutant deficient in the DUF490 motif of DR_146T; ∆DR_146T, mutant deficient in DR_146T.

Mentions: Under continuous vortexing, the survival fraction of ∆DR_146T was substantially lower than that of the wild type (Fig. 4), consistent with the survival phenotype of the SlpA mutant28. The survival of ∆DR_146T-DUF490 was slightly lower than that of the wild type. Fig. 5 shows that the cell resistance of ∆DR_146T and ∆DR_146T-DUF490 to osmotic pressure was lower than that of the wild type, indicating that mutation-induced deficiency in cell envelope integrity led to higher sensitivity to osmotic pressure. These suggest that DR_146T contributes to stress resistance, and the DUF490 motif might be less important than the TamB motif for the function of DR_146T.


A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans
Survival of D. radiodurans wild type and mutant strains to shear stress.The survival fraction of ∆DR_146T was substantially lower than that for the wild type and ∆DR_146T-DUF490 under shear stress. DRWT, D. radiodurans wild type; ∆DR_146T-DUF490, mutant deficient in the DUF490 motif of DR_146T; ∆DR_146T, mutant deficient in DR_146T.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382914&req=5

f4: Survival of D. radiodurans wild type and mutant strains to shear stress.The survival fraction of ∆DR_146T was substantially lower than that for the wild type and ∆DR_146T-DUF490 under shear stress. DRWT, D. radiodurans wild type; ∆DR_146T-DUF490, mutant deficient in the DUF490 motif of DR_146T; ∆DR_146T, mutant deficient in DR_146T.
Mentions: Under continuous vortexing, the survival fraction of ∆DR_146T was substantially lower than that of the wild type (Fig. 4), consistent with the survival phenotype of the SlpA mutant28. The survival of ∆DR_146T-DUF490 was slightly lower than that of the wild type. Fig. 5 shows that the cell resistance of ∆DR_146T and ∆DR_146T-DUF490 to osmotic pressure was lower than that of the wild type, indicating that mutation-induced deficiency in cell envelope integrity led to higher sensitivity to osmotic pressure. These suggest that DR_146T contributes to stress resistance, and the DUF490 motif might be less important than the TamB motif for the function of DR_146T.

View Article: PubMed Central - PubMed

ABSTRACT

The translocation and assembly module (TAM) in bacteria consists of TamA and TamB that form a complex to control the transport and secretion of outer membrane proteins. Herein, we demonstrated that the DR_1462-DR_1461-DR_1460 gene loci on chromosome 1 of Deinococcus radiodurans, which lacks tamA homologs, is a tamB homolog (DR_146T) with two tamB motifs and a DUF490 motif. Mutation of DR_146T resulted in cell envelope peeling and a decrease in resistance to shear stress and osmotic pressure, as well as an increase in oxidative stress resistance, consistent with the phenotype of a surface layer (S-layer) protein SlpA (DR_2577) mutant, demonstrating the involvement of DR_146T in maintenance of cell envelope integrity. The 123 kDa SlpA was absent and only its fragments were present in the cell envelope of DR_146T mutant, suggesting that DR_146T might be involved in maintenance of the S-layer. A mutant lacking the DUF490 motif displayed only a slight alteration in phenotype compared with the wild type, suggesting DUF490 is less important than tamB motif for the function of DR_146T. These findings enhance our understanding of the properties of the multilayered envelope in extremophilic D. radiodurans, as well as the diversity and functions of TAMs in bacteria.

No MeSH data available.