Hydrodynamics of bacteriophage migration along bacterial flagella
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Citations
The architecture and stabilisation of flagellotropic tailed bacteriophages.
The flagellotropic bacteriophage YSD1 targets Salmonella Typhi with a Chi‐like protein tail fibre
Spreading of biologically relevant liquids over the laser textured surfaces.
Genome sequence analysis of the temperate bacteriophage TBP2 of the solvent producer Clostridium saccharoperbutylacetonicum N1-4 (HMT, ATCC 27021).
The nut-and-bolt motion of a bacteriophage sliding along a bacterial flagellum: a complete hydrodynamics model
References
Is phage DNA "injected" into cells - biologists and physicists can agree
Flagellar determinants of bacterial sensitivity to chi-phage.
Primary Adsorption Site of Phage PBS1: the Flagellum of Bacillus subtilis
A Mutant of Salmonella Possessing Straight Flagella
The structure of Bacillus subtilis bacteriophage PBS 1
Related Papers (5)
Frequently Asked Questions (17)
Q2. What future works have the authors mentioned in the paper "Hydrodynamics of bacteriophage migration along bacterial flagella" ?
This opens up the possibility of a competition between the nut-and-bolt translocation effect and the possibly opposing drag due to translation, which will vary with the helical angle of the flagellar filament. Future studies could address the transient period of wrapping, where the length of the fibres wrapped around the filament is increasing and the ‘ grip ’ is possibly becoming tighter. The authors hope that the modelling developed in this paper will motivate not only further theoretical studies along those lines but also more experimental work clarifying the processes involved in the wrapping and motion of the fibre in the grooves.
Q3. What is the effect of the term involving Lfib on the fibres?
The presence of the term involving Lfib in the denominator of Eq. 63 leads to a decrease of U with Lfib, and is physically due to an increase of the viscous drag on the fibres as Lfib increases.
Q4. What is the drag anisotropy of the filament?
the very drag anisotropy that allows the rotation of helical flagellar filaments to propel bacteria in the bulk will also enable the rotation of helical fibres around a smooth filament to lead to translocation along the axis of the filament.
Q5. What is the common prefactor in the formulae for the speed of the phage?
The common prefactor in the formulae for the translocation speed along the filament, U ∼ −hωflRfl sinα cosα, appears in the expressions from both models.
Q6. How do the authors capture the effect of the grooves?
The authors implicitly capture the effect of the grooves (i) by imposing that the fibres that emanate from the bottom of the tail of the phage are wrapped around the flagellar filament in a helical shape and (ii) via the anisotropy in the drag arising from the relative motion between the fibres and the rotating flagellar filament.
Q7. What is the effect of the helical wrapping of the fibres on the phage?
The assumption of a helical wrapping of the fibres coupled with this anisotropy simulates the guiding effect of the grooves in this first model by resisting motion perpendicular to the local tangent of the grooves and promoting motion parallel to it.
Q8. what is the restoring force of the fibre?
A simple modelling approach consists of viewing each side13of the groove as repelling the fibre, with the resultant of these forces providing a restoring force hkδbfib(s) per unit length, arising from a potential well 12kδ2 where δ is the distance from the centre of the well, and bfib is the local binormal vector to the fibre centreline,bfib =[ h cosα sin ( sRfl/ sinα) ,− cosα cos ( sRfl/ sinα) , h sinα ] , (44)that lies in the local tangent plane of the surface of the flagellar filament and is perpendicular to the tangent vector tfib of the fibre centreline.
Q9. What is the z-component of the torque on the phage tail?
The drag force and torque due to the motion of the head in the otherwise stagnant fluid are given byFhead = −6πµahurelhead, (13) ez ·Mhead = ez · [ −6πµah ( rh ∧ urelhead )] − 8πµa3hωp, (14)8 with urelh given byurelh = ωp (ez ∧ rh) + Uez. (15)Taking th = ttail, the centre of the head will be located at position rh = rb +
Q10. What is the helical shape of the flagellar filament?
5. With the assumption that the gap between the fibres and the flagellar filament is negligible compared to the radius Rfl of the flagellar filament, the centreline rfib(s) of the fibres, parametrised by6the contour length position s, is described mathematically asrfib(s) = ( Rfl cos ( sRfl/ sinα) , hRfl sin ( sRfl/ sinα) , s cosα ) , −LLfib < s < LRfib, (1)with total contour length Lfib = L L fib + L R fib, where the authors allow for fibres extending to both sides of the base of the tail to have lengths LLfib (left side) and L R fib (right side).
Q11. What is the significance of the factor hRflfl sin co?
Here again, the crucial factor −hRflωfl sinα cosα appears in both equations multiplying a positive, non-dimensional expression, and the authors obtain the correct directionality and speed of translocation in agreement with Ref. [27].
Q12. What are the main theoretical observations and predictions of Refs?
These mathematical results capture the basic qualitative experimental observations and predictions of Refs. [23, 27] for the speed and directionality of translocation which are both crucial for successful infection.
Q13. What is the directionality of the phage?
The factor −hωfl gives a directionality for U in agreement with the qualitative prediction of Ref. [27] that CCW rotation will only pull the phage toward the cell body if the phage slides along a right-handed groove.
Q14. What is the z-component of the drag anisotropy for the fibre?
These results are valid in the limit in which the distance d between the fibre and the surface of the flagellar filaments is much smaller than the radius of the flagellar filament (d Rfl), such that the surface of the smooth flagellar filament is locally planar.
Q15. What is the effect of the term Lt in Eq. 40?
The long-tailed approximation from Eq. 63, through the terms with Lt in both numerator and denominator, is able to capture the increasing behaviour of U with Lt. Physically, this trend is caused by the propulsive terms in ez ·Mtail in Eq. 40 (proportional to L3t ) that increase as Lt increases.
Q16. What is the difference between the two models?
17The important point where the two models deviate from each other is their opposite predictions for the translocation speed as a function of the phage tail length and the phage fibre length.
Q17. What is the effect of the translation on the phage?
there will be an additional hydrodynamic drag on the phage due to the rotation and translation of the flagellar filament.