Sinorhizobium meliloti Chemoreceptor McpU Mediates Chemotaxis toward Host Plant Exudates through Direct Proline Sensing

Webb, Benjamin A.; Hildreth, Sherry B.; Helm, Richard F.; Scharf, Birgit E.

doi:10.1128/aem.00115-14

Cited by 72 publications

(76 citation statements)

References 87 publications

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“…Homology modeling predicted the involvement of asp-182 together with asp-155 in ligand coordination, by forming hydrogen bonds between their oxygen atoms and the amino group of the ligand. This prediction was experimentally supported for the binding of pro to McpU in vivo and in vitro (Webb et al 2014). Since ligand coordination Cache is an acronym formed from the names of proteins in which these signaling domains were recognized (animal Ca 2+ channel subunits and prokaryotic chemotaxis receptors) (Anantharaman and Aravind 2000); TM1 and TM2 are transmembrane regions 1 and 2; HAMP is the conserved signal transduction domain in histidine kinases, adenylyl cyclases, methyl-accepting chemotaxis proteins, and phosphatases (Aravind and Ponting 1999); MH is a methyl-accepting helix; signaling is the methyl-accepting chemotaxis protein signaling domain and interaction site for CheA and CheW.…”

Section: Thermal Denaturation Of Mcpu-pr With Aamentioning

confidence: 89%

“…We also tested the response of the mcpU deletion strain, because experimental and bioinformatics evidence suggested that McpU serves as a general aa sensor (Webb et al 2014(Webb et al , 2016. Chemotactic responses of both strains were observed in a modified hydrogel capillary assay, which enables quantitative time-course assessments (Webb et al 2016).…”

Section: Resultsmentioning

confidence: 99%

“…Homology modeling of the periplasmic region of McpU (McpU-PR), with the crystal structure of Vibrio cholerae McpN as the template, identified the ligand-binding site and, specifically, two conserved aspartate residues (asp-155 and asp-182) of the N-terminal cache domain to be involved in ligand sensing. The prediction was supported by chemotaxis behavioral assays of single point mutants and in vitro binding analysis of purified mutant variant proteins (Webb et al 2014). The recognized motif, also known as a double PhoQ-DcuS-CitA (PDC) domain, recognizes aa directly as well as indirectly through ABC transport-binding lipoproteins (Anantharaman and Aravind 2000;Glekas et al 2012;McKellar et al 2015;Reyes-Darias et al 2015;Ulrich and Zhulin 2005;Webb et al 2014).…”

mentioning

confidence: 97%

“…The complex molecular composition of seed exudates comprises amino acids (aa), sugars, lipids, phenolics, proteins, and other metabolites (Barbour et al 1991;Nelson 2004;Webb et al 2014). Positive chemotactic responses to host seed exudates were described for Bradyhizobium japonicum, R. leguminosarum, and S. meliloti (Barbour et al 1991;Gaworzewska and Carlile 1982;Webb et al 2014).…”

mentioning

confidence: 99%

“…We previously presented that McpU senses proline (pro) via tandem cache domains located in its periplasmic region (Anantharaman and Aravind 2000;Webb et al 2014). The domain architecture of McpU is depicted in Figure 1.…”

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confidence: 99%

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Sinorhizobium meliloti Chemotaxis to Multiple Amino Acids Is Mediated by the Chemoreceptor McpU

Webb

Compton

Campo

et al. 2017

MPMI

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The legume symbiont Sinorhizobium meliloti is chemoattracted to compounds exuded by germinating seeds of its host alfalfa. This response is mainly mediated by the S. meliloti chemoreceptor McpU. McpU also has a prominent contribution in sensing a synthetic amino acid (aa) mixture mimicking the amounts and composition observed in seed exudate. Here, we used the hydrogel capillary assay to quantify chemotactic responses of S. meliloti to individual aa exuded by germinating alfalfa seeds and to define the role of McpU in this behavior. S. meliloti exhibited positive chemotaxis responses to all proteinogenic aa, except for aspartate, and to citrulline, cystine, gamma-aminobutyric acid, and ornithine. Wild-type responses were diverse in intensity, while a strain lacking mcpU displayed strongly diminished responses. Differential scanning fluorimetry demonstrated interaction of the purified periplasmic region of McpU (McpU-PR) with the aa, except glutamate and aspartate. We additionally tested organic acids and sugars, but there were no significant interactions with the McpU ligand-binding domain, except for citrate. Using ligand displacement, we confirmed the interaction of McpU-PR with aa representing strong and weak attractants. Our results show that S. meliloti McpU is a broad-range aa receptor mediating differential responses to individual attractants, which does not bind negatively charged aa.

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Section: Thermal Denaturation Of Mcpu-pr With Aamentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Sinorhizobium meliloti Chemotaxis to Multiple Amino Acids Is Mediated by the Chemoreceptor McpU

Webb

Compton

Campo

et al. 2017

MPMI

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The structural analysis of the periplasmic domain of Sinorhizobium meliloti chemoreceptor McpZ reveals a novel fold and suggests a complex mechanism of transmembrane signaling

et al. 2023

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Chemotaxis is a fundamental process whereby bacteria seek out nutrient sources and avoid harmful chemicals. For the symbiotic soil bacterium Sinorhizobium meliloti, the chemotaxis system also plays an essential role in the interaction with its legume host. The chemotactic signaling cascade is initiated through interactions of an attractant or repellent compound with chemoreceptors or methyl‐accepting chemotaxis proteins (MCPs). S. meliloti possesses eight chemoreceptors to mediate chemotaxis. Six of these receptors are transmembrane proteins with periplasmic ligand‐binding domains (LBDs). The specific functions of McpW and McpZ are still unknown. Here, we report the crystal structure of the periplasmic domain of McpZ (McpZPD) at 2.7 Å resolution. McpZPD assumes a novel fold consisting of three concatenated four‐helix bundle modules. Through phylogenetic analyses, we discovered that this helical tri‐modular domain fold arose within the Rhizobiaceae family and is still evolving rapidly. The structure, offering a rare view of a ligand‐free dimeric MCP‐LBD, reveals a novel dimerization interface. Molecular dynamics calculations suggest ligand binding will induce conformational changes that result in large horizontal helix movements within the membrane‐proximal domains of the McpZPD dimer that are accompanied by a 5 Å vertical shift of the terminal helix toward the inner cell membrane. These results suggest a mechanism of transmembrane signaling for this family of MCPs that entails both piston‐type and scissoring movements. The predicted movements terminate in a conformation that closely mirrors those observed in related ligand‐bound MCP‐LBDs.

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Phylogenetic and Protein Sequence Analysis of Bacterial Chemoreceptors

Ortega

Zhulin

2018

Methods in Molecular Biology

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Sinorhizobium meliloti Chemoreceptor McpU Mediates Chemotaxis toward Host Plant Exudates through Direct Proline Sensing

Cited by 72 publications

References 87 publications

Sinorhizobium meliloti Chemotaxis to Multiple Amino Acids Is Mediated by the Chemoreceptor McpU

Sinorhizobium meliloti Chemotaxis to Multiple Amino Acids Is Mediated by the Chemoreceptor McpU

The structural analysis of the periplasmic domain of Sinorhizobium meliloti chemoreceptor McpZ reveals a novel fold and suggests a complex mechanism of transmembrane signaling

Phylogenetic and Protein Sequence Analysis of Bacterial Chemoreceptors

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