Limits...
Single-molecule study on histone-like nucleoid-structuring protein (H-NS) paralogue in Pseudomonas aeruginosa: MvaU bears DNA organization mode similarities to MvaT.

Winardhi RS, Castang S, Dove SL, Yan J - PLoS ONE (2014)

Bottom Line: Using single-molecule stretching and imaging experiments, we found striking similarities in the DNA organization modes of MvaU compared to the previously studied MvaT.Similar to MvaT, MvaU filament can mediate DNA bridging while excessive MvaU can cause DNA aggregation.The almost identical DNA organization modes of MvaU and MvaT explain their functional redundancy, and raise an interesting question regarding the evolutionary benefits of having multiple H-NS paralogues in the Pseudomonas genus.

View Article: PubMed Central - PubMed

Affiliation: NUS Graduate school for Integrative Sciences and Engineering, Singapore, Singapore; Mechanobiology Institute, National University of Singapore, Singapore, Singapore; Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore.

ABSTRACT
Pseudomonas aeruginosa contains two distinct members of H-NS family of nucleoid-structuring proteins: MvaT and MvaU. Together, these proteins bind to the same regions of the chromosome and function coordinately in the regulation of hundreds of genes. Due to their structural similarity, they can associate to form heteromeric complexes. These findings left us wondering whether they bear similar DNA binding properties that underlie their gene-silencing functions. Using single-molecule stretching and imaging experiments, we found striking similarities in the DNA organization modes of MvaU compared to the previously studied MvaT. MvaU can form protective nucleoprotein filaments that are insensitive to environmental factors, consistent with its role as a repressor of gene expression. Similar to MvaT, MvaU filament can mediate DNA bridging while excessive MvaU can cause DNA aggregation. The almost identical DNA organization modes of MvaU and MvaT explain their functional redundancy, and raise an interesting question regarding the evolutionary benefits of having multiple H-NS paralogues in the Pseudomonas genus.

Show MeSH

Related in: MedlinePlus

Sequence alignment and predicted secondary structure of MvaT and MvaU.(A) The sequence alignment was done with ClustalW2 [46], [47], with 46% pairwise identity. An * (asterisk) indicates positions which have a single, fully conserved residue, a : (colon) indicates conservation between groups of strongly similar properties, and a . (period) indicates conservation between groups of weakly similar properties. (B) The secondary structures were predicted using a consensus prediction method [48]. Blue vertical bars represent a-helix, red vertical bars represent extended strand, purple vertical bars represent random coil, and gray vertical bars represent ambiguous states.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4221281&req=5

pone-0112246-g001: Sequence alignment and predicted secondary structure of MvaT and MvaU.(A) The sequence alignment was done with ClustalW2 [46], [47], with 46% pairwise identity. An * (asterisk) indicates positions which have a single, fully conserved residue, a : (colon) indicates conservation between groups of strongly similar properties, and a . (period) indicates conservation between groups of weakly similar properties. (B) The secondary structures were predicted using a consensus prediction method [48]. Blue vertical bars represent a-helix, red vertical bars represent extended strand, purple vertical bars represent random coil, and gray vertical bars represent ambiguous states.

Mentions: H-NS paralogues also exist in other species of bacteria, some of which can functionally substitute for H-NS and complement an E. coli H-NS deficient mutant invivo despite their lack of sequence similarity and identity to E. coli H-NS [14]–[16]. In Pseudomonas, MvaT and MvaU have been identified as the paralogues of H-NS that share structural and functional similarity to H-NS despite sharing <20% sequence identity to H-NS [16] (see Figure 1 for sequence alignment and predicted structural elements of MvaT and MvaU). Transcriptional profiling using DNA microarrays revealed that MvaT from Pseudomonas aeruginosa regulates the expression of hundreds of genes [17]–[19]. Moreover, MvaU has been shown to function coordinately with MvaT, occupying the same regions of the chromosome and co-regulating the expression of ∼350 genes [20]. The amount of genes they regulate is similar to that regulated by H-NS and StpA in E. coli, which have intracellular concentrations of few micromolar [21]. Therefore, we reason that MvaT and MvaU have similar intracellular concentrations. The deletion of either MvaT or MvaU leads to the increase in production of the other, indicating cross-regulation of the two proteins and that they can functionally compensate each other [22]. In addition, MvaT and MvaU show a binding preference for AT-rich regions of the chromosome, suggesting that these proteins are involved in xenogeneic DNA silencing [20]. This preferential binding to AT-rich regions seems to be shared among H-NS family proteins [23]–[26]. Other than the AT-rich preferential binding, in general H-NS family proteins bind DNA non-specifically, which is consistent with their role as abundant nucleoid associated proteins that play a crucial role in organizing chromosomes.


Single-molecule study on histone-like nucleoid-structuring protein (H-NS) paralogue in Pseudomonas aeruginosa: MvaU bears DNA organization mode similarities to MvaT.

Winardhi RS, Castang S, Dove SL, Yan J - PLoS ONE (2014)

Sequence alignment and predicted secondary structure of MvaT and MvaU.(A) The sequence alignment was done with ClustalW2 [46], [47], with 46% pairwise identity. An * (asterisk) indicates positions which have a single, fully conserved residue, a : (colon) indicates conservation between groups of strongly similar properties, and a . (period) indicates conservation between groups of weakly similar properties. (B) The secondary structures were predicted using a consensus prediction method [48]. Blue vertical bars represent a-helix, red vertical bars represent extended strand, purple vertical bars represent random coil, and gray vertical bars represent ambiguous states.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4221281&req=5

pone-0112246-g001: Sequence alignment and predicted secondary structure of MvaT and MvaU.(A) The sequence alignment was done with ClustalW2 [46], [47], with 46% pairwise identity. An * (asterisk) indicates positions which have a single, fully conserved residue, a : (colon) indicates conservation between groups of strongly similar properties, and a . (period) indicates conservation between groups of weakly similar properties. (B) The secondary structures were predicted using a consensus prediction method [48]. Blue vertical bars represent a-helix, red vertical bars represent extended strand, purple vertical bars represent random coil, and gray vertical bars represent ambiguous states.
Mentions: H-NS paralogues also exist in other species of bacteria, some of which can functionally substitute for H-NS and complement an E. coli H-NS deficient mutant invivo despite their lack of sequence similarity and identity to E. coli H-NS [14]–[16]. In Pseudomonas, MvaT and MvaU have been identified as the paralogues of H-NS that share structural and functional similarity to H-NS despite sharing <20% sequence identity to H-NS [16] (see Figure 1 for sequence alignment and predicted structural elements of MvaT and MvaU). Transcriptional profiling using DNA microarrays revealed that MvaT from Pseudomonas aeruginosa regulates the expression of hundreds of genes [17]–[19]. Moreover, MvaU has been shown to function coordinately with MvaT, occupying the same regions of the chromosome and co-regulating the expression of ∼350 genes [20]. The amount of genes they regulate is similar to that regulated by H-NS and StpA in E. coli, which have intracellular concentrations of few micromolar [21]. Therefore, we reason that MvaT and MvaU have similar intracellular concentrations. The deletion of either MvaT or MvaU leads to the increase in production of the other, indicating cross-regulation of the two proteins and that they can functionally compensate each other [22]. In addition, MvaT and MvaU show a binding preference for AT-rich regions of the chromosome, suggesting that these proteins are involved in xenogeneic DNA silencing [20]. This preferential binding to AT-rich regions seems to be shared among H-NS family proteins [23]–[26]. Other than the AT-rich preferential binding, in general H-NS family proteins bind DNA non-specifically, which is consistent with their role as abundant nucleoid associated proteins that play a crucial role in organizing chromosomes.

Bottom Line: Using single-molecule stretching and imaging experiments, we found striking similarities in the DNA organization modes of MvaU compared to the previously studied MvaT.Similar to MvaT, MvaU filament can mediate DNA bridging while excessive MvaU can cause DNA aggregation.The almost identical DNA organization modes of MvaU and MvaT explain their functional redundancy, and raise an interesting question regarding the evolutionary benefits of having multiple H-NS paralogues in the Pseudomonas genus.

View Article: PubMed Central - PubMed

Affiliation: NUS Graduate school for Integrative Sciences and Engineering, Singapore, Singapore; Mechanobiology Institute, National University of Singapore, Singapore, Singapore; Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore.

ABSTRACT
Pseudomonas aeruginosa contains two distinct members of H-NS family of nucleoid-structuring proteins: MvaT and MvaU. Together, these proteins bind to the same regions of the chromosome and function coordinately in the regulation of hundreds of genes. Due to their structural similarity, they can associate to form heteromeric complexes. These findings left us wondering whether they bear similar DNA binding properties that underlie their gene-silencing functions. Using single-molecule stretching and imaging experiments, we found striking similarities in the DNA organization modes of MvaU compared to the previously studied MvaT. MvaU can form protective nucleoprotein filaments that are insensitive to environmental factors, consistent with its role as a repressor of gene expression. Similar to MvaT, MvaU filament can mediate DNA bridging while excessive MvaU can cause DNA aggregation. The almost identical DNA organization modes of MvaU and MvaT explain their functional redundancy, and raise an interesting question regarding the evolutionary benefits of having multiple H-NS paralogues in the Pseudomonas genus.

Show MeSH
Related in: MedlinePlus