The Outer Membrane Protein TolC from <i>Sinorhizobium meliloti</i> Affects Protein Secretion, Polysaccharide Biosynthesis, Antimicrobial Resistance, and Symbiosis

Cosme, Ana M.; Becker, Anke; Santos, Mário R.; Sharypova, L. A.; Santos, Pedro M.; Moreira, Leonilde M.

doi:10.1094/mpmi-21-7-0947

Cited by 49 publications

(48 citation statements)

References 55 publications

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“…Deletions of the two RNDtype pumps, SMc01094-SMc01095 (smeCD) or SMc01828-SMc01829 (smeEF), in a ⌬smeAB background resulted in a further increase in susceptibility to chloramphenicol and nali- dixic acid or to erythromycin and tetracycline, respectively (Table 2; see also Table S3 in the supplemental material). Consistent with the findings of Cosme et al (8), deletion of the tolC gene resulted in increased susceptibility to antibiotics, detergents, dyes, and plant-derived chemicals (Table 2). Deletions in the remaining two OMF genes, SMa1037 and SMc02281, had no effect on antimicrobial susceptibility in both wild-type and ⌬tolC backgrounds (see Table S3 in the supplemental material), indicating that the SMa1037 and SMc02281 proteins are not involved in the efflux of toxic substances tested.…”

Section: Identification Of Multicomponent-type Mdr Pump Genessupporting

confidence: 89%

“…The MFP genes were located adjacent to all of the RND genes. A computational search for the OMF family proteins of S. meliloti identified SMc02082 (designated TolC) (8). This study also identified two sequences, designated SMc1037 and SMc02281, encoding the outer membrane efflux protein motif (Pfam ID PF02321), but these sequences were not analyzed because they displayed low similarity to E. coli TolC and each had a possible lipid attachment site, unlike TolC (8).…”

Section: Identification Of Multicomponent-type Mdr Pump Genesmentioning

confidence: 99%

“…In Sinorhizobium meliloti, a symbiont of alfalfa, the OMF family protein TolC has recently been characterized by Cosme et al (8). A tolC mutant strain of S. meliloti was highly sensitive to antibiotics, detergents, and plant-derived compounds and formed no, or very few, nodules on alfalfa roots.…”

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confidence: 99%

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Involvement of the SmeAB Multidrug Efflux Pump in Resistance to Plant Antimicrobials and Contribution to Nodulation Competitiveness in Sinorhizobium meliloti

Eda

Mitsui

Minamisawa

2011

Appl Environ Microbiol

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The contributions of multicomponent-type multidrug efflux pumps to antimicrobial resistance and nodulation ability in Sinorhizobium meliloti were comprehensively analyzed. Computational searches identified genes in the S. meliloti strain 1021 genome encoding 1 pump from the ATP-binding cassette family, 3 pumps from the major facilitator superfamily, and 10 pumps from the resistance-nodulation-cell division family, and subsequently, these genes were deleted either individually or simultaneously. Antimicrobial susceptibility tests demonstrated that deletion of the smeAB pump genes resulted in increased susceptibility to a range of antibiotics, dyes, detergents, and plant-derived compounds and, further, that specific deletion of the smeCD or smeEF genes in a ⌬smeAB background caused a further increase in susceptibility to certain antibiotics. Competitive nodulation experiments revealed that the smeAB mutant was defective in competing with the wild-type strain for nodulation. The introduction of a plasmid carrying smeAB into the smeAB mutant restored antimicrobial resistance and nodulation competitiveness. These findings suggest that the SmeAB pump, which is a major multidrug efflux system of S. meliloti, plays an important role in nodulation competitiveness by mediating resistance toward antimicrobial compounds produced by the host plant.

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Section: Identification Of Multicomponent-type Mdr Pump Genessupporting

confidence: 89%

Section: Identification Of Multicomponent-type Mdr Pump Genesmentioning

confidence: 99%

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Involvement of the SmeAB Multidrug Efflux Pump in Resistance to Plant Antimicrobials and Contribution to Nodulation Competitiveness in Sinorhizobium meliloti

Eda

Mitsui

Minamisawa

2011

Appl Environ Microbiol

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“…The increased diameter (from 13.5 to 29.0 Å) upon TolC-AcrA association, would admit the translocation of larger molecules, which is in agreement with other strong and recent experimental evidences. [17][18][19] The new proposed model also satisfied the Cryo-EM map volume described by Du et al 6 as seen in Figure 4c. Torres et al 2385 Vol.…”

Section: Resultssupporting

confidence: 70%

Alternative Model for RND-Type Efflux Pump

Tôrres¹,

Pascutti²,

Bisch³

et al. 2016

Journal of the Brazilian Chemical Society

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RND (resistance-nodulation-division) transporters are found in several Gram-negative bacteria species. These proteins form a complex along with membrane fusion proteins and outer membrane factors. This complex acts as an efflux pump, transporting several different molecules directly from the cytoplasm to the extracellular medium. Although the crystallographic structure of each protein of the complex is known, the complete complex assembly is not yet fully characterized. In 2014, a model for the complete system, based upon a cryoelectron-microscopy map, was proposed. In the present work, we propose an alternative model that also satisfies the volume obtained from the cryoelectron-microscopy assay. In this model, the AcrA helical domains are interleaved to the helical domains of the TolC protein, increasing the diameter of the formed pore. We believe that this model represents a better model for RND-type efflux pump and might contribute to the characterization of this system. Keywords: RND efflux system, comparative modeling, efflux pump, molecular modeling, protein structure IntroductionMulti-drug resistance systems, like the resistancenodulation-division RND-type efflux pump, play a crucial role on the adaptation of bacteria to toxic environments and are key components on cellular extrusion of structurally diverse antimicrobials in Gram-negative bacteria. 1These systems are composed of at least three different protein families. In Escherichia coli the AcrA-AcrB-TolC complex is a model system for the RND-type pump. AcrB is located at the inner membrane and is responsible for the translocation of several compounds from the cytoplasm to the periplasm, powered by a proton antiport mechanism. AcrA, located at the periplasm, acts as an adaptor protein, believed to assemble in a hexameric disposition. Finally, TolC forms a pore across the outer membrane, connecting the periplasm and the extracellular environment. Some authors have raised hypothesis regarding the assembly of the complex AcrAB-TolC, nevertheless the exact spatial conformation is still a matter of debate.3-5 In 2014, Du et al. 6 built AcrA-AcrB constructs and performed electron microscopy and cryo-electron microscopy assays that provided significant understanding of the complete pump assembly. It was proposed that TolC and AcrB are connected by the association with AcrA and that the former proteins make no direct contact, which is corroborated by cryo-electron microscopy density map. The model proposed by Du et al. 6 was in good agreement with previous works in what regarded the 3:6:3 stoichiometry ratio (AcrB:AcrA:TolC). 7 On the other hand, the proposed model had some very interesting novel features, as, for example, the fact that TolC and AcrB made no direct contact. The AcrA-TolC contact interface, as presented by the referred work, considered the TolC coiled-coils to be located inside the AcrA-formed pore lumen. This mode of interaction was based solely on the cryo-EM data, despite the fact that crystallographic data for the intermeshing cogwheel-t...

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“…The complete channel exports virulence-associated proteins, antibiotics, detergents, colicin V, and organic solvents (67). The TolC protein plays an important role in the virulence of many Gram-negative bacterial pathogens (7,11,13,22,32,46). Thus, TolC should not be overlooked for its possible role in protein secretion in rickettsiae.…”

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confidence: 99%

TolC-Dependent Secretion of an Ankyrin Repeat-Containing Protein of Rickettsia typhi

et al. 2012

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bRickettsia typhi, the causative agent of murine (endemic) typhus, is an obligate intracellular pathogen with a life cycle involving both vertebrate and invertebrate hosts. In this study, we characterized a gene (RT0218) encoding a C-terminal ankyrin repeat domain-containing protein, named Rickettsia ankyrin repeat protein 1 (RARP-1), and identified it as a secreted effector protein of R. typhi. RT0218 showed differential transcript abundance at various phases of R. typhi intracellular growth. RARP-1 was secreted by R. typhi into the host cytoplasm during in vitro infection of mammalian cells. Transcriptional analysis revealed that RT0218 was cotranscribed with adjacent genes RT0217 (hypothetical protein) and RT0216 (TolC) as a single polycistronic mRNA. Given one of its functions as a facilitator of extracellular protein secretion in some Gram-negative bacterial pathogens, we tested the possible role of TolC in the secretion of RARP-1. Using Escherichia coli C600 and an isogenic tolC insertion mutant as surrogate hosts, our data demonstrate that RARP-1 is secreted in a TolC-dependent manner. Deletion of either the N-terminal signal peptide or the C-terminal ankyrin repeats abolished RARP-1 secretion by wild-type E. coli. Importantly, expression of R. typhi tolC in the E. coli tolC mutant restored the secretion of RARP-1, suggesting that TolC has a role in RARP-1 translocation across the outer membrane. This work implies that the TolC component of the putative type 1 secretion system of R. typhi is involved in the secretion process of RARP-1.

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The Outer Membrane Protein TolC from Sinorhizobium meliloti Affects Protein Secretion, Polysaccharide Biosynthesis, Antimicrobial Resistance, and Symbiosis

Cited by 49 publications

References 55 publications

Involvement of the SmeAB Multidrug Efflux Pump in Resistance to Plant Antimicrobials and Contribution to Nodulation Competitiveness in Sinorhizobium meliloti

Involvement of the SmeAB Multidrug Efflux Pump in Resistance to Plant Antimicrobials and Contribution to Nodulation Competitiveness in Sinorhizobium meliloti

Alternative Model for RND-Type Efflux Pump

TolC-Dependent Secretion of an Ankyrin Repeat-Containing Protein of Rickettsia typhi

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