Structural biology of the Gram-negative bacterial conjugation systems

Ilangovan, Aravindan; Connery, Sarah; Waksman, Gabriel

doi:10.1016/j.tim.2015.02.012

Cited by 96 publications

(81 citation statements)

References 72 publications

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“…During the classical conjugation process in Gram-negative bacteria, plasmid DNA travels through a type IV secretion system (T4SS) between donor and recipient bacteria (58,59). Conjugative plasmids carry all the genetic information required to synthetize the T4SS and the proteins needed to escort plasmid DNA to the new host (3).…”

Section: Conjugationmentioning

confidence: 99%

“…Conjugation provides plasmids with the opportunity to replicate horizontally, and, all else being equal, this should increase the relative frequency of the plasmid in the population. However, conjugation is energetically expensive (it requires three plasmid-encoded ATPases [58]) and entails a reduction in bacterial host fitness, thus reducing the rate of vertical plasmid transmission (60). The fitness cost associated with conjugation comes primarily from the high ATP demand for mating-channel formation and plasmid DNA translocation (58).…”

Section: Conjugationmentioning

confidence: 99%

“…However, conjugation is energetically expensive (it requires three plasmid-encoded ATPases [58]) and entails a reduction in bacterial host fitness, thus reducing the rate of vertical plasmid transmission (60). The fitness cost associated with conjugation comes primarily from the high ATP demand for mating-channel formation and plasmid DNA translocation (58). To minimize this cost, plasmids tightly control the expression of conjugative systems (41,(61)(62)(63).…”

Section: Conjugationmentioning

confidence: 99%

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Fitness Costs of Plasmids: a Limit to Plasmid Transmission

2017

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Plasmids mediate the horizontal transmission of genetic information between bacteria, facilitating their adaptation to multiple environmental conditions. An especially important example of the ability of plasmids to catalyze bacterial adaptation and evolution is their instrumental role in the global spread of antibiotic resistance, which constitutes a major threat to public health. Plasmids provide bacteria with new adaptive tools, but they also entail a metabolic burden that, in the absence of selection for plasmid-encoded traits, reduces the competitiveness of the plasmid-carrying clone. Although this fitness reduction can be alleviated over time through compensatory evolution, the initial cost associated with plasmid carriage is the main constraint on the vertical and horizontal replication of these genetic elements. The fitness effects of plasmids therefore have a crucial influence on their ability to associate with new bacterial hosts and consequently on the evolution of plasmid-mediated antibiotic resistance. However, the molecular mechanisms underlying plasmid fitness cost remain poorly understood. Here, we analyze the literature in the field and examine the potential fitness effects produced by plasmids throughout their life cycle in the host bacterium. We also explore the various mechanisms evolved by plasmids and bacteria to minimize the cost entailed by these mobile genetic elements. Finally, we discuss potential future research directions in the field.

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Section: Conjugationmentioning

confidence: 99%

Section: Conjugationmentioning

confidence: 99%

Section: Conjugationmentioning

confidence: 99%

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Fitness Costs of Plasmids: a Limit to Plasmid Transmission

2017

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“…Conjugation is the principal means by which horizontal gene transfer, a process crucial for the spread of antibiotic resistance genes among bacterial populations, is mediated 97 . Bacterial conjugation in Gramnegative bacteria involves two main structures: i) a versatile type IV secretion system (T4SS) responsible for assembling the conjugative pilus, and of secreting different types of cargos, ranging from ssDNA, proteins or protein-DNA complexes and ii) a dynamic conjugative pilus able to extend and retract 98,99 . Many types of conjugative pilus have been described 100 , however this section will focus on the F pilus as it represents the best functionally and structurally characterised example.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive guide to pilus biogenesis in Gram-negative bacteria

2017

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Pili are critical virulence factors of many Gram-negative pathogens. These surface structures provide bacteria with a link to their outside environments, allowing bacteria to interact with their hosts, other surfaces or with each other. They can even provide a conduit for the exchange of information. The surface chemistries and other biophysical properties of pili are uniquely adapted to the environmental challenges faced by bacteria. The assembly of these surface structures presents a molecular engineering challenge, which bacteria have solved in a variety of unique ways. In this review, we examine recent advances in our structural understanding of various Gram-negative pilus systems and discuss their functional implications.

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“…The relaxase is loaded onto a region of the plasmid called the origin of transfer or oriT with the assistance of 2–3 auxiliary proteins (Zechner et al , 2012; Ilangovan et al , 2015). Once loaded, the relaxase nicks oriT at a site called nic , and covalently reacts to the resulting 5′‐phosphate.…”

Section: Introductionmentioning

confidence: 99%

Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery

et al. 2017

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Type IV secretion (T4S) systems are versatile bacterial secretion systems mediating transport of protein and/or DNA. T4S systems are generally composed of 11 VirB proteins and 1 VirD protein (VirD4). The VirB1‐11 proteins assemble to form a secretion machinery and a pilus while the VirD4 protein is responsible for substrate recruitment. The structure of VirD4 in isolation is known; however, its structure bound to the VirB1‐11 apparatus has not been determined. Here, we purify a T4S system with VirD4 bound, define the biochemical requirements for complex formation and describe the protein–protein interaction network in which VirD4 is involved. We also solve the structure of this complex by negative stain electron microscopy, demonstrating that two copies of VirD4 dimers locate on both sides of the apparatus, in between the VirB4 ATPases. Given the central role of VirD4 in type IV secretion, our study provides mechanistic insights on a process that mediates the dangerous spread of antibiotic resistance genes among bacterial populations.

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Structural biology of the Gram-negative bacterial conjugation systems

Cited by 96 publications

References 72 publications

Fitness Costs of Plasmids: a Limit to Plasmid Transmission

Fitness Costs of Plasmids: a Limit to Plasmid Transmission

A comprehensive guide to pilus biogenesis in Gram-negative bacteria

Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery

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