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Activity of Bdellovibrio hit locus proteins, Bd0108 and Bd0109, links Type IVa pilus extrusion/retraction status to prey-independent growth signalling.

Capeness MJ, Lambert C, Lovering AL, Till R, Uchida K, Chaudhuri R, Alderwick LJ, Lee DJ, Swarbreck D, Liddell S, Aizawa S, Sockett RE - PLoS ONE (2013)

Bottom Line: We find that deletion of the whole bd0108 gene greatly reduced the extrusion of pili, whereas the 42 bp deletion caused greater pilus extrusion than wild-type.Bd0109 has a sugar binding YD- repeat motif and an N-terminus with a putative pilin-like fold and was found to interact directly with Bd0108.These results lead us to propose that the Bd0109/Bd0108 interaction regulates pilus production in Bdellovibrio (possibly by interaction with the pilus fibre at the cell wall), and that the presence (and possibly retraction state) of the pilus feeds back to alter the growth state of the Bdellovibrio cell.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.

ABSTRACT
Bdellovibrio bacteriovorus are facultatively predatory bacteria that grow within gram-negative prey, using pili to invade their periplasmic niche. They also grow prey-independently on organic nutrients after undergoing a reversible switch. The nature of the growth switching mechanism has been elusive, but several independent reports suggested mutations in the hit (host-interaction) locus on the Bdellovibrio genome were associated with the transition to prey-independent growth. Pili are essential for prey entry by Bdellovibrio and sequence analysis of the hit locus predicted that it was part of a cluster of Type IVb pilus-associated genes, containing bd0108 and bd0109. In this study we have deleted the whole bd0108 gene, which is unique to Bdellovibrio, and compared its phenotype to strains containing spontaneous mutations in bd0108 and the common natural 42 bp deletion variant of bd0108. We find that deletion of the whole bd0108 gene greatly reduced the extrusion of pili, whereas the 42 bp deletion caused greater pilus extrusion than wild-type. The pili isolated from these strains were comprised of the Type IVa pilin protein; PilA. Attempts to similarly delete gene bd0109, which like bd0108 encodes a periplasmic/secreted protein, were not successful, suggesting that it is likely to be essential for Bdellovibrio viability in any growth mode. Bd0109 has a sugar binding YD- repeat motif and an N-terminus with a putative pilin-like fold and was found to interact directly with Bd0108. These results lead us to propose that the Bd0109/Bd0108 interaction regulates pilus production in Bdellovibrio (possibly by interaction with the pilus fibre at the cell wall), and that the presence (and possibly retraction state) of the pilus feeds back to alter the growth state of the Bdellovibrio cell. We further identify a novel small RNA encoded by the hit locus, the transcription of which is altered in different bd0108 mutation backgrounds.

Show MeSH
Alignment of Bd0109 with other RHS elements.Multiple sequence alignment constructed using Clustal W showing that the main regions of homology between the Bdellovibrio Bd0109 predicted protein and other RHS elements is the core pFAM RHS repeat (PF05593) region which consists of a repeating YD element. The whole Bd0109 sequence contains 13 YD or YE sequences and several other Y residues. The sequences aligned are from the genera indicated with the names, with the second Dickeya sequence being RhsB.
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pone-0079759-g007: Alignment of Bd0109 with other RHS elements.Multiple sequence alignment constructed using Clustal W showing that the main regions of homology between the Bdellovibrio Bd0109 predicted protein and other RHS elements is the core pFAM RHS repeat (PF05593) region which consists of a repeating YD element. The whole Bd0109 sequence contains 13 YD or YE sequences and several other Y residues. The sequences aligned are from the genera indicated with the names, with the second Dickeya sequence being RhsB.

Mentions: Taken together, the work so far on RHS elements suggest that the common attribute may be a sugar binding YD-repeat region (of widely varying size due to different numbers of repeats) with variable N- and C- termini which could confer a wide variety of functions. There are no determined structures for a member of the YD-repeat family; however, the (predicted) β-rich architecture and carbohydrate binding function mirror that of the wider beta-solenoid grouping e.g. toxin A of Clostridium difficile [37] or the LytA cell-wall binding protein [38]. Multiple sequence alignment (Figure 7) shows that the majority of sequence similarity of Bd0109 with RHS elements is to the YD-repeat core.


Activity of Bdellovibrio hit locus proteins, Bd0108 and Bd0109, links Type IVa pilus extrusion/retraction status to prey-independent growth signalling.

Capeness MJ, Lambert C, Lovering AL, Till R, Uchida K, Chaudhuri R, Alderwick LJ, Lee DJ, Swarbreck D, Liddell S, Aizawa S, Sockett RE - PLoS ONE (2013)

Alignment of Bd0109 with other RHS elements.Multiple sequence alignment constructed using Clustal W showing that the main regions of homology between the Bdellovibrio Bd0109 predicted protein and other RHS elements is the core pFAM RHS repeat (PF05593) region which consists of a repeating YD element. The whole Bd0109 sequence contains 13 YD or YE sequences and several other Y residues. The sequences aligned are from the genera indicated with the names, with the second Dickeya sequence being RhsB.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818213&req=5

pone-0079759-g007: Alignment of Bd0109 with other RHS elements.Multiple sequence alignment constructed using Clustal W showing that the main regions of homology between the Bdellovibrio Bd0109 predicted protein and other RHS elements is the core pFAM RHS repeat (PF05593) region which consists of a repeating YD element. The whole Bd0109 sequence contains 13 YD or YE sequences and several other Y residues. The sequences aligned are from the genera indicated with the names, with the second Dickeya sequence being RhsB.
Mentions: Taken together, the work so far on RHS elements suggest that the common attribute may be a sugar binding YD-repeat region (of widely varying size due to different numbers of repeats) with variable N- and C- termini which could confer a wide variety of functions. There are no determined structures for a member of the YD-repeat family; however, the (predicted) β-rich architecture and carbohydrate binding function mirror that of the wider beta-solenoid grouping e.g. toxin A of Clostridium difficile [37] or the LytA cell-wall binding protein [38]. Multiple sequence alignment (Figure 7) shows that the majority of sequence similarity of Bd0109 with RHS elements is to the YD-repeat core.

Bottom Line: We find that deletion of the whole bd0108 gene greatly reduced the extrusion of pili, whereas the 42 bp deletion caused greater pilus extrusion than wild-type.Bd0109 has a sugar binding YD- repeat motif and an N-terminus with a putative pilin-like fold and was found to interact directly with Bd0108.These results lead us to propose that the Bd0109/Bd0108 interaction regulates pilus production in Bdellovibrio (possibly by interaction with the pilus fibre at the cell wall), and that the presence (and possibly retraction state) of the pilus feeds back to alter the growth state of the Bdellovibrio cell.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.

ABSTRACT
Bdellovibrio bacteriovorus are facultatively predatory bacteria that grow within gram-negative prey, using pili to invade their periplasmic niche. They also grow prey-independently on organic nutrients after undergoing a reversible switch. The nature of the growth switching mechanism has been elusive, but several independent reports suggested mutations in the hit (host-interaction) locus on the Bdellovibrio genome were associated with the transition to prey-independent growth. Pili are essential for prey entry by Bdellovibrio and sequence analysis of the hit locus predicted that it was part of a cluster of Type IVb pilus-associated genes, containing bd0108 and bd0109. In this study we have deleted the whole bd0108 gene, which is unique to Bdellovibrio, and compared its phenotype to strains containing spontaneous mutations in bd0108 and the common natural 42 bp deletion variant of bd0108. We find that deletion of the whole bd0108 gene greatly reduced the extrusion of pili, whereas the 42 bp deletion caused greater pilus extrusion than wild-type. The pili isolated from these strains were comprised of the Type IVa pilin protein; PilA. Attempts to similarly delete gene bd0109, which like bd0108 encodes a periplasmic/secreted protein, were not successful, suggesting that it is likely to be essential for Bdellovibrio viability in any growth mode. Bd0109 has a sugar binding YD- repeat motif and an N-terminus with a putative pilin-like fold and was found to interact directly with Bd0108. These results lead us to propose that the Bd0109/Bd0108 interaction regulates pilus production in Bdellovibrio (possibly by interaction with the pilus fibre at the cell wall), and that the presence (and possibly retraction state) of the pilus feeds back to alter the growth state of the Bdellovibrio cell. We further identify a novel small RNA encoded by the hit locus, the transcription of which is altered in different bd0108 mutation backgrounds.

Show MeSH