Complete Genomic Structure of the Cultivated Rice Endophyte Azospirillum sp. B510

Kaneko, Takakazu; Minamisawa, Kiwamu; Isawa, Toyoharu; Nakatsukasa, Hiroki; Mitsui, Hisayuki; Kawaharada, Yasuyuki; Nakamura, Yasukazu; Watanabe, Akïharu; Kawashima, Kumiko; Ono, Akiko; Shimizu, Yoshimi; Takahashi, Chika; Minami, Chiharu; Fujishiro, Tsunakazu; Kohara, Mitsuyo; Katoh, Midori; Nakazaki, Naomi; Nakayama, Shinobu; Yamada, Manabu; Tabata, Satoshi; Sato, Shusei

doi:10.1093/dnares/dsp026

Cited by 147 publications

(85 citation statements)

References 72 publications

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“…None of the other Azospirillum species strains sequenced to date shows evidence of a similar domain insertion (34)(35)(36)(37)(38)(39). In fact, the draft genome of an Sp7 strain generated by a team of South Korean scientists also lacks the TMX fusion to CheA1 (NCBI BioProject PRJNA293508).…”

Section: Discussionmentioning

confidence: 99%

“…In fact, the draft genome of an Sp7 strain generated by a team of South Korean scientists also lacks the TMX fusion to CheA1 (NCBI BioProject PRJNA293508). A. brasilense genomes are organized as 7 replicons: one chromosome and 6 large plasmids named p1 through p6 (34)(35)(36)(37)(38)(39). The DNA regions coding for CheA1 and for TMX are both located on the largest plasmid, p1, in all A. brasilense strains with available genome sequences, but they are not adjacent and are separated by several kilobases, precluding a simple frameshifting or slippage mutation between adjacent genes.…”

Section: Discussionmentioning

confidence: 99%

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Distinct Domains of CheA Confer Unique Functions in Chemotaxis and Cell Length in Azospirillum brasilense Sp7

2017

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Chemotaxis is the movement of cells in response to gradients of diverse chemical cues. Motile bacteria utilize a conserved chemotaxis signal transduction system to bias their motility and navigate through a gradient. A central regulator of chemotaxis is the histidine kinase CheA. This cytoplasmic protein interacts with membrane-bound receptors, which assemble into large polar arrays, to propagate the signal. In the alphaproteobacterium Azospirillum brasilense, Che1 controls transient increases in swimming speed during chemotaxis, but it also biases the cell length at division. However, the exact underlying molecular mechanisms for Che1-dependent control of multiple cellular behaviors are not known. Here, we identify specific domains of the CheA1 histidine kinase implicated in modulating each of these functions. We show that CheA1 is produced in two isoforms: a membraneanchored isoform produced as a fusion with a conserved seven-transmembrane domain of unknown function (TMX) at the N terminus and a soluble isoform similar to prototypical CheA. Site-directed and deletion mutagenesis combined with behavioral assays confirm the role of CheA1 in chemotaxis and implicate the TMX domain in mediating changes in cell length. Fluorescence microscopy further reveals that the membrane-anchored isoform is distributed around the cell surface while the soluble isoform localizes at the cell poles. Together, the data provide a mechanism for the role of Che1 in controlling multiple unrelated cellular behaviors via acquisition of a new domain in CheA1 and production of distinct functional isoforms.IMPORTANCE Chemotaxis provides a significant competitive advantage to bacteria in the environment, and this function has been transferred laterally multiple times, with evidence of functional divergence in different genomic contexts. The molecular principles that underlie functional diversification of chemotaxis in various genomic contexts are unknown. Here, we provide a molecular mechanism by which a single CheA protein controls two unrelated functions: chemotaxis and cell length. Acquisition of this multifunctionality is seemingly a recent evolutionary event. The findings illustrate a mechanism by which chemotaxis function may be co-opted to regulate additional cellular functions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Distinct Domains of CheA Confer Unique Functions in Chemotaxis and Cell Length in Azospirillum brasilense Sp7

2017

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“…. However, it is also possible that these strains lack a nitrite reduction pathway as nirK of several Azospirillum strains is located on plasmids (Pothier et al, 2008;Kaneko et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Identification and isolation of active N2O reducers in rice paddy soil

et al. 2011

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Dissolved N 2 O is occasionally detected in surface and ground water in rice paddy fields, whereas little or no N 2 O is emitted to the atmosphere above these fields. This indicates the occurrence of N 2 O reduction in rice paddy fields; however, identity of the N 2 O reducers is largely unknown. In this study, we employed both culture-dependent and culture-independent approaches to identify N 2 O reducers in rice paddy soil. In a soil microcosm, N 2 O and succinate were added as the electron acceptor and donor, respectively, for N 2 O reduction. For the stable isotope probing (SIP) experiment, 13 C-labeled succinate was used to identify succinate-assimilating microbes under N 2 O-reducing conditions. DNA was extracted 24 h after incubation, and heavy and light DNA fractions were separated by density gradient ultracentrifugation. Denaturing gradient gel electrophoresis and clone library analysis targeting the 16S rRNA and the N 2 O reductase gene were performed. For culture-dependent analysis, the microbes that elongated under N 2 O-reducing conditions in the presence of cell-division inhibitors were individually captured by a micromanipulator and transferred to a low-nutrient medium. The N 2 O-reducing ability of these strains was examined by gas chromatography/mass spectrometry. Results of the SIP analysis suggested that Burkholderiales and Rhodospirillales bacteria dominated the population under N 2 O-reducing conditions, in contrast to the control sample (soil incubated with only 13 C-succinate). Results of the single-cell isolation technique also indicated that the majority of the N 2 O-reducing strains belonged to the genera Herbaspirillum (Burkholderiales) and Azospirillum (Rhodospirillales). In addition, Herbaspirillum strains reduced N 2 O faster than Azospirillum strains. These results suggest that Herbaspirillum spp. may have an important role in N 2 O reduction in rice paddy soils.

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“…Primers used in the primary reaction were 5'-TTGAGGGTCCGGCATCAG-3' and 5'-TCAGGAAGTCCGTATGGCGTT-3', and those in the sec-ondary reaction were 5'-CGTCCCTCGACACCAGCAC-3' and 5'-GTCGCCTTGTGGGCTTGC-3', designed from the sequence of the 16S-23S internal transcribed spacer (ITS) region of strain B510 (Accession No. AP010947) (10). PCRs were run in 25-µL volumes containing 10 µL (primary reaction) or 2 µL (secondary reaction) of template, 2 pmol primers, 1.5 mM magnesium chloride, 200 µM dNTPs, and 0.1 U of Taq DNA polymerase (Takara Bio, Otsu, Japan).…”

mentioning

confidence: 99%

Azospirillum sp. Strain B510 Enhances Rice Growth and Yield

Isawa¹,

Yasuda²,

Awazaki³

et al. 2010

Microb. Environ.

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Inoculation experiments with the endophytic bacterium Azospirillum sp. strain B510, an isolate from surface-sterilized stems of field-grown rice, were conducted in pots in a greenhouse, and in paddy fields in Hokkaido, Japan. B510 significantly enhanced the growth of newly generated leaves and shoot biomass under greenhouse conditions. When rice seedlings were treated with 1×10 8 CFU ml −1 , then transplanted to paddy fields, tiller numbers and seed yield significantly increased. Azospirillum sp. strain B510 is a promising bacterial inoculant for plant growth promotion and agricultural practices.

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Complete Genomic Structure of the Cultivated Rice Endophyte Azospirillum sp. B510

Cited by 147 publications

References 72 publications

Distinct Domains of CheA Confer Unique Functions in Chemotaxis and Cell Length in Azospirillum brasilense Sp7

Distinct Domains of CheA Confer Unique Functions in Chemotaxis and Cell Length in Azospirillum brasilense Sp7

Identification and isolation of active N2O reducers in rice paddy soil

Azospirillum sp. Strain B510 Enhances Rice Growth and Yield

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