Rhizobial homologs of the fatty acid transporter FadL facilitate perception of long-chain acyl-homoserine lactone signals

Krol, Elizaveta; Becker, Anke

doi:10.1073/pnas.1404929111

Cited by 46 publications

(36 citation statements)

References 32 publications

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“…FadL, 50 S3b) to describe the 303→504 comlink, which was similar to the one used for the 113→203 comlink, except that two additional compartments surrounding the 303-transmitter and 504-receiver, were added along with transport coefficients that describe the influx and efflux of 3OC 12 HSL between the extracellular space and the membrane, and between the membrane and the intracellular space. In particular, in terms of the deterministic model offered in the supplement, the sequestration is treated as diffusion with two different rates.…”

Section: Resultsmentioning

confidence: 99%

Wiring Together Synthetic Bacterial Consortia to Create a Biological Integrated Circuit

2016

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The promise of adapting biology to information processing will not be realized until engineered gene circuits, operating in different cell populations, can be wired together to express a predictable function. Here, elementary biological integrated circuits (BICs), consisting of two sets of transmitter and receiver gene circuit modules with embedded memory placed in separate cell populations, were meticulously assembled using live cell lithography and wired together by the mass transport of quorum-sensing (QS) signal molecules to form two isolated communication links (comlinks). The comlink dynamics were tested by broadcasting "clock" pulses of inducers into the networks and measuring the responses of functionally linked fluorescent reporters, and then modeled through simulations that realistically captured the protein production and molecular transport. These results show that the comlinks were isolated and each mimicked aspects of the synchronous, sequential networks used in digital computing. The observations about the flow conditions, derived from numerical simulations, and the biofilm architectures that foster or silence cell-to-cell communications have implications for everything from decontamination of drinking water to bacterial virulence.

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Section: Resultsmentioning

confidence: 99%

Wiring Together Synthetic Bacterial Consortia to Create a Biological Integrated Circuit

2016

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“…All constructs were verified by sequencing. Plasmids were transferred to S. meliloti by E. coli S17-1-mediated conjugation as previously described (60,61). Correct plasmid integrations were verified by PCR.…”

Section: Methodsmentioning

confidence: 99%

AraC-like transcriptional activator CuxR binds c-di-GMP by a PilZ-like mechanism to regulate extracellular polysaccharide production

Schäper

Steinchen

Krol

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Cyclic dimeric GMP (c-di-GMP) has emerged as a key regulatory player in the transition between planktonic and sedentary biofilm-associated bacterial lifestyles. It controls a multitude of processes including production of extracellular polysaccharides (EPSs). The PilZ domain, consisting of an N-terminal “RxxxR” motif and a β-barrel domain, represents a prototype c-di-GMP receptor. We identified a class of c-di-GMP–responsive proteins, represented by the AraC-like transcription factor CuxR in plant symbiotic α-proteobacteria. In Sinorhizobium meliloti, CuxR stimulates transcription of an EPS biosynthesis gene cluster at elevated c-di-GMP levels. CuxR consists of a Cupin domain, a helical hairpin, and bipartite helix-turn-helix motif. Although unrelated in sequence, the mode of c-di-GMP binding to CuxR is highly reminiscent to that of PilZ domains. c-di-GMP interacts with a conserved N-terminal RxxxR motif and the Cupin domain, thereby promoting CuxR dimerization and DNA binding. We unravel structure and mechanism of a previously unrecognized c-di-GMP–responsive transcription factor and provide insights into the molecular evolution of c-di-GMP binding to proteins.

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“…All constructs were verified by sequencing. Plasmids were transferred to S. meliloti by E. coli S17-1-mediated conjugation (35) as previously described (36).…”

Section: Methodsmentioning

confidence: 99%

“…Two replicate S. meliloti TY cultures were induced with 100 M IPTG at an OD 600 of 0.05 and grown for 24 h. Cultures were centrifuged for 10 min at 15,000 ϫ g. Twenty microliters of supernatant was applied to an N-acyl-homoserine lactone (AHL) detection assay using A. tumefaciens NTL4(pZLR4) that was performed as previously described (36).…”

Section: Methodsmentioning

confidence: 99%

Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti

et al. 2016

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Sinorhizobium meliloti undergoes major lifestyle changes between planktonic states, biofilm formation, and symbiosis with leguminous plant hosts. In many bacteria, the second messenger 3=,5=-cyclic di-GMP (c-di-GMP, or cdG) promotes a sessile lifestyle by regulating a plethora of processes involved in biofilm formation, including motility and biosynthesis of exopolysaccharides (EPS). Here, we systematically investigated the role of cdG in S. meliloti Rm2011 encoding 22 proteins putatively associated with cdG synthesis, degradation, or binding. Single mutations in 21 of these genes did not cause evident changes in biofilm formation, motility, or EPS biosynthesis. In contrast, manipulation of cdG levels by overproducing endogenous or heterologous diguanylate cyclases (DGCs) or phosphodiesterases (PDEs) affected these processes and accumulation of N-Acyl-homoserine lactones in the culture supernatant. Specifically, individual overexpression of the S. meliloti genes pleD, SMb20523, SMb20447, SMc01464, and SMc03178 encoding putative DGCs and of SMb21517 encoding a single-domain PDE protein had an impact and resulted in increased levels of cdG. Compared to the wild type, an S. meliloti strain that did not produce detectable levels of cdG (cdG 0 ) was more sensitive to acid stress. However, it was symbiotically potent, unaffected in motility, and only slightly reduced in biofilm formation. The SMc01790-SMc01796 locus, homologous to the Agrobacterium tumefaciens uppABCDEF cluster governing biosynthesis of a unipolarly localized polysaccharide, was found to be required for cdG-stimulated biofilm formation, while the single-domain PilZ protein McrA was identified as a cdG receptor protein involved in regulation of motility. IMPORTANCEWe present the first systematic genome-wide investigation of the role of 3=,5=-cyclic di-GMP (c-di-GMP, or cdG) in regulation of motility, biosynthesis of exopolysaccharides, biofilm formation, quorum sensing, and symbiosis in a symbiotic alpha-rhizobial species. Phenotypes of an S. meliloti strain unable to produce cdG (cdG 0 ) demonstrated that this second messenger is not essential for root nodule symbiosis but may contribute to acid tolerance. Our data further suggest that enhanced levels of cdG promote sessility of S. meliloti and uncovered a single-domain PilZ protein as regulator of motility.

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Rhizobial homologs of the fatty acid transporter FadL facilitate perception of long-chain acyl-homoserine lactone signals

Cited by 46 publications

References 32 publications

Wiring Together Synthetic Bacterial Consortia to Create a Biological Integrated Circuit

Wiring Together Synthetic Bacterial Consortia to Create a Biological Integrated Circuit

AraC-like transcriptional activator CuxR binds c-di-GMP by a PilZ-like mechanism to regulate extracellular polysaccharide production

Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti

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