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

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.


Growth of D. radiodurans wild type and mutant strains.The growth of DR_146T mutant (∆DR_146T, black) and SlpA mutant (∆DR_2577, purple) were much slower than that of the wild type (DRWT, blue), while the growth of the mutant deficient in the DUF490 motif of DR_146T (∆DR_146T-DUF490, green) was only slightly slower than that of the wild type. Cell growth was monitored by measuring the OD600 of cell cultures.
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f2: Growth of D. radiodurans wild type and mutant strains.The growth of DR_146T mutant (∆DR_146T, black) and SlpA mutant (∆DR_2577, purple) were much slower than that of the wild type (DRWT, blue), while the growth of the mutant deficient in the DUF490 motif of DR_146T (∆DR_146T-DUF490, green) was only slightly slower than that of the wild type. Cell growth was monitored by measuring the OD600 of cell cultures.

Mentions: The growth of the DR_146T mutant (∆DR_146T) and the mutant deficient in DUF490 (∆DR_146T-DUF490) were slower than that of the wild type (Fig. 2). The DR_146T mutant grew twice as slowly as the wild type, while ∆DR_146T-DUF490 had only a slightly longer doubling time than the wild type. These results indicate that DR_146T might play an important role in cell growth or cell division. Moreover, the growth defect phenotype of ∆DR_146T is similar to that of the SlpA (DR_2577) mutant (Fig. 2), suggesting that DR_146T might contribute to cell envelope integrity along with the S-layer components.


A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans
Growth of D. radiodurans wild type and mutant strains.The growth of DR_146T mutant (∆DR_146T, black) and SlpA mutant (∆DR_2577, purple) were much slower than that of the wild type (DRWT, blue), while the growth of the mutant deficient in the DUF490 motif of DR_146T (∆DR_146T-DUF490, green) was only slightly slower than that of the wild type. Cell growth was monitored by measuring the OD600 of cell cultures.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Growth of D. radiodurans wild type and mutant strains.The growth of DR_146T mutant (∆DR_146T, black) and SlpA mutant (∆DR_2577, purple) were much slower than that of the wild type (DRWT, blue), while the growth of the mutant deficient in the DUF490 motif of DR_146T (∆DR_146T-DUF490, green) was only slightly slower than that of the wild type. Cell growth was monitored by measuring the OD600 of cell cultures.
Mentions: The growth of the DR_146T mutant (∆DR_146T) and the mutant deficient in DUF490 (∆DR_146T-DUF490) were slower than that of the wild type (Fig. 2). The DR_146T mutant grew twice as slowly as the wild type, while ∆DR_146T-DUF490 had only a slightly longer doubling time than the wild type. These results indicate that DR_146T might play an important role in cell growth or cell division. Moreover, the growth defect phenotype of ∆DR_146T is similar to that of the SlpA (DR_2577) mutant (Fig. 2), suggesting that DR_146T might contribute to cell envelope integrity along with the S-layer components.

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.