메뉴 건너뛰기




Volumn 184, Issue 20, 2002, Pages 5686-5695

Characterization of the Sinorhizobium meliloti sinR/sinI locus and the production of novel N-acyl homoserine lactones

Author keywords

[No Author keywords available]

Indexed keywords

BACTERIAL PROTEIN; HOMOSERINE; LACTONE; PROTEIN SINI; PROTEIN SINR; UNCLASSIFIED DRUG;

EID: 0036786039     PISSN: 00219193     EISSN: None     Source Type: Journal    
DOI: 10.1128/JB.184.20.5686-5695.2002     Document Type: Article
Times cited : (220)

References (50)
  • 2
    • 0028849833 scopus 로고
    • Synthesis of multiple exoproducts in Pseudomonas aeruginosa is under the control of RhlR-RhlI, another set of regulators in strain PAO1 with homology to the autoinducer-responsive LuxR-LuxI family
    • Brint, J. M., and D. E. Ohman. 1995. Synthesis of multiple exoproducts in Pseudomonas aeruginosa is under the control of RhlR-RhlI, another set of regulators in strain PAO1 with homology to the autoinducer-responsive LuxR-LuxI family. J. Bacteriol, 177:7155-7163.
    • (1995) J. Bacteriol. , vol.177 , pp. 7155-7163
    • Brint, J.M.1    Ohman, D.E.2
  • 4
    • 0029730638 scopus 로고    scopus 로고
    • A special acyl carrier protein for transferring long hydroxylated fatty acids to lipid A in Rhizobium
    • Brozek, K. A., R. W. Carlson, and C. R. Raetz. 1996. A special acyl carrier protein for transferring long hydroxylated fatty acids to lipid A in Rhizobium. J. Biol. Chem. 271:32126-32136.
    • (1996) J. Biol. Chem. , vol.271 , pp. 32126-32136
    • Brozek, K.A.1    Carlson, R.W.2    Raetz, C.R.3
  • 6
    • 0032211618 scopus 로고    scopus 로고
    • Production of acyl-homoserine lactone quorum-sensing signals by Gram-negative plant-associated bacteria
    • Cha, C., P. Gao, Y. C. Chen, P. D. Shaw, and S. K. Farrand. 1998. Production of acyl-homoserine lactone quorum-sensing signals by Gram-negative plant-associated bacteria. Mol. Plant-Microbe Interact. 11:1119-1129.
    • (1998) Mol. Plant-Microbe Interact. , vol.11 , pp. 1119-1129
    • Cha, C.1    Gao, P.2    Chen, Y.C.3    Shaw, P.D.4    Farrand, S.K.5
  • 7
    • 0026623152 scopus 로고
    • Molecular characterization and regulation of the rhizosphere-expressed genes rhiABCR that can influence nodulation by Rhizobium leguminosarum biovar viciae
    • Cubo, M. T., A. Economou, G. Murphy, A. W. Johnston, and J. A. Downie. 1992. Molecular characterization and regulation of the rhizosphere-expressed genes rhiABCR that can influence nodulation by Rhizobium leguminosarum biovar viciae. J. Bacteriol. 174:4026-4035.
    • (1992) J. Bacteriol. , vol.174 , pp. 4026-4035
    • Cubo, M.T.1    Economou, A.2    Murphy, G.3    Johnston, A.W.4    Downie, J.A.5
  • 9
    • 0033862847 scopus 로고    scopus 로고
    • Bacterial quorum sensing in pathogenic relationships
    • de Kievit, T. R., and B. H. Iglewski. 2000. Bacterial quorum sensing in pathogenic relationships. Infect. Immun. 68:4839-4849.
    • (2000) Infect. Immun. , vol.68 , pp. 4839-4849
    • De Kievit, T.R.1    Iglewski, B.H.2
  • 10
    • 0029904404 scopus 로고    scopus 로고
    • Rhizobium lipo-chitooligosaccharide nodulation factors: Signaling molecules mediating recognition and morphogenesis
    • Denarie, J., F. Debelle, and J. C. Prome. 1996. Rhizobium lipo-chitooligosaccharide nodulation factors: signaling molecules mediating recognition and morphogenesis. Annu. Rev. Biochem. 65:503-535.
    • (1996) Annu. Rev. Biochem. , vol.65 , pp. 503-535
    • Denarie, J.1    Debelle, F.2    Prome, J.C.3
  • 12
    • 0025979786 scopus 로고
    • Synthesis of the lux gene autoinducer in Vibrio fischeri is positively autoregulated
    • Eberhard, A., T. Longin, C. A. Widrig, and S. J. Stranick. 1991. Synthesis of the lux gene autoinducer in Vibrio fischeri is positively autoregulated. Arch. Microbiol. 155:294-297.
    • (1991) Arch. Microbiol. , vol.155 , pp. 294-297
    • Eberhard, A.1    Longin, T.2    Widrig, C.A.3    Stranick, S.J.4
  • 13
    • 0020724032 scopus 로고
    • Bacterial bioluminescence: Isolation and genetic analysis of functions from Vibrio fischeri
    • Engebrecht, J., K. Nealson, and M. Silverman. 1983. Bacterial bioluminescence: isolation and genetic analysis of functions from Vibrio fischeri. Cell 32:773-781.
    • (1983) Cell , vol.32 , pp. 773-781
    • Engebrecht, J.1    Nealson, K.2    Silverman, M.3
  • 14
    • 0031689645 scopus 로고    scopus 로고
    • Characterization of a novel acyl carrier protein, RkpF, encoded by an operon involved in capsular polysaccharide biosynthesis in Sinorhizobium meliloti
    • Epple, G., K. M. van der Drift, J. E. Thomas-Oates, and O. Geiger. 1998. Characterization of a novel acyl carrier protein, RkpF, encoded by an operon involved in capsular polysaccharide biosynthesis in Sinorhizobium meliloti. J. Bacteriol. 180:4950-4954.
    • (1998) J. Bacteriol. , vol.180 , pp. 4950-4954
    • Epple, G.1    Van der Drift, K.M.2    Thomas-Oates, J.E.3    Geiger, O.4
  • 15
    • 0032035296 scopus 로고    scopus 로고
    • Self perception in bacteria: Quorum sensing with acylated homoserine lactones
    • Fuqua, C., and E. P. Greenberg. 1998. Self perception in bacteria: quorum sensing with acylated homoserine lactones. Curr. Opin. Microbiol. 1:183-189.
    • (1998) Curr. Opin. Microbiol. , vol.1 , pp. 183-189
    • Fuqua, C.1    Greenberg, E.P.2
  • 16
    • 0035675837 scopus 로고    scopus 로고
    • Regulation of gene expression by cell-to-cell communication: Acyl-homoserine lactone quorum sensing
    • Fuqua, C., M. R. Parsek, and E. P. Greenberg. 2001. Regulation of gene expression by cell-to-cell communication: acyl-homoserine lactone quorum sensing. Annu. Rev. Genet. 35:439-468.
    • (2001) Annu. Rev. Genet. , vol.35 , pp. 439-468
    • Fuqua, C.1    Parsek, M.R.2    Greenberg, E.P.3
  • 17
    • 0027957161 scopus 로고
    • Quorum sensing in bacteria: The LuxR-LuxI family of cell density-responsive transcriptional regulators
    • Fuqua, W. C., S. C. Winans, and E. P. Greenberg. 1994. Quorum sensing in bacteria: the LuxR-LuxI family of cell density-responsive transcriptional regulators. J. Bacteriol. 176:269-275.
    • (1994) J. Bacteriol. , vol.176 , pp. 269-275
    • Fuqua, W.C.1    Winans, S.C.2    Greenberg, E.P.3
  • 19
    • 0034947940 scopus 로고    scopus 로고
    • Integration of PCR fragments at any specific site within cloning vectors without the use of restriction enzymes and DNA ligase
    • Geiser, M., R. Cebe, D. Drewello, and R. Schmitz. 2001. Integration of PCR fragments at any specific site within cloning vectors without the use of restriction enzymes and DNA ligase. BioTechniques 31:88-92.
    • (2001) BioTechniques , vol.31 , pp. 88-92
    • Geiser, M.1    Cebe, R.2    Drewello, D.3    Schmitz, R.4
  • 20
    • 0025748804 scopus 로고
    • Genetic techniques in Rhizobium meliloti
    • Glazebrook, J., and G. C. Walker. 1991. Genetic techniques in Rhizobium meliloti. Methods Enzymol. 204:398-418.
    • (1991) Methods Enzymol. , vol.204 , pp. 398-418
    • Glazebrook, J.1    Walker, G.C.2
  • 21
    • 0030034468 scopus 로고    scopus 로고
    • Cell-to-cell signaling in the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum: Autoinduction of a stationary phase and rhizosphere-expressed genes
    • Gray, K. M., J. P. Pearson, J. A. Downie, B. E. Boboye, and E. P. Greenberg. 1996. Cell-to-cell signaling in the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum: autoinduction of a stationary phase and rhizosphere-expressed genes. J. Bacteriol. 178:372-376.
    • (1996) J. Bacteriol. , vol.178 , pp. 372-376
    • Gray, K.M.1    Pearson, J.P.2    Downie, J.A.3    Boboye, B.E.4    Greenberg, E.P.5
  • 22
    • 0028945107 scopus 로고
    • Evidence that the N-terminal region of the Vibrio fischeri LuxR protein constitutes an autoinducer-binding domain
    • Hanzelka, B. L., and E. P. Greenberg. 1995. Evidence that the N-terminal region of the Vibrio fischeri LuxR protein constitutes an autoinducer-binding domain. J. Bacteriol. 177:815-817.
    • (1995) J. Bacteriol. , vol.177 , pp. 815-817
    • Hanzelka, B.L.1    Greenberg, E.P.2
  • 23
    • 0026432638 scopus 로고
    • Activation of Escherichia coli prohaemolysin to the mature toxin by acyl carrier protein-dependent fatty acylation
    • Issartel, J. P., V. Koronakis, and C. Hughes. 1991. Activation of Escherichia coli prohaemolysin to the mature toxin by acyl carrier protein-dependent fatty acylation. Nature 351:759-761.
    • (1991) Nature , vol.351 , pp. 759-761
    • Issartel, J.P.1    Koronakis, V.2    Hughes, C.3
  • 24
    • 77956862571 scopus 로고
    • Lipid metabolism in procaryotes
    • J. E. Vance and D. E. Vance (ed.). Elsevier, Amsterdam, The Netherlands
    • Jackowski, S., J. E. J. Cronan, and C. O. Rock. 1991. Lipid metabolism in procaryotes, p. 43-85. In J. E. Vance and D. E. Vance (ed.), Biochemistry of lipids, lipoproteins and membranes. Elsevier, Amsterdam, The Netherlands.
    • (1991) Biochemistry of lipids, lipoproteins and membranes , pp. 43-85
    • Jackowski, S.1    Cronan, J.E.J.2    Rock, C.O.3
  • 25
    • 0028148276 scopus 로고
    • Multiple N-acyl-L-homoserine lactone autoinducers of luminescence in the marine symbiotic bacterium Vibrio fischeri
    • Kuo, A., N. V. Blough, and P. V. Dunlap. 1994. Multiple N-acyl-L-homoserine lactone autoinducers of luminescence in the marine symbiotic bacterium Vibrio fischeri. J. Bacteriol. 176:7558-7565.
    • (1994) J. Bacteriol. , vol.176 , pp. 7558-7565
    • Kuo, A.1    Blough, N.V.2    Dunlap, P.V.3
  • 26
    • 0030066649 scopus 로고    scopus 로고
    • Modulation of luminescence operon expression by N-octanoyl-L-homoserine lactone in ainS mutants of Vibrio fischeri
    • Kuo, A., S. M. Callahan, and P. V. Dunlap. 1996. Modulation of luminescence operon expression by N-octanoyl-L-homoserine lactone in ainS mutants of Vibrio fischeri. J. Bacteriol. 178:971-976.
    • (1996) J. Bacteriol. , vol.178 , pp. 971-976
    • Kuo, A.1    Callahan, S.M.2    Dunlap, P.V.3
  • 27
    • 0033764087 scopus 로고    scopus 로고
    • The biocontrol strain Pseudomonas fluorescens F113 produces the Rhizobium small bacteriocin, N-(3-hydroxy-7-cis-tetradecenoyl)homoserine lactone, via HdtS, a putative novel N-acylhomoserine lactone synthase
    • Laue, B. E., Y. Jiang, S. R. Chhabra, S. Jacob, G. S. Stewart, A. Hardman, J. A. Downie, F. O'Gara, and P. Williams. 2000. The biocontrol strain Pseudomonas fluorescens F113 produces the Rhizobium small bacteriocin, N-(3-hydroxy-7-cis-tetradecenoyl)homoserine lactone, via HdtS, a putative novel N-acylhomoserine lactone synthase. Microbiology 146:2469-2480.
    • (2000) Microbiology , vol.146 , pp. 2469-2480
    • Laue, B.E.1    Jiang, Y.2    Chhabra, S.R.3    Jacob, S.4    Stewart, G.S.5    Hardman, A.6    Downie, J.A.7    O'Gara, F.8    Williams, P.9
  • 28
    • 0010269952 scopus 로고
    • Exopolysaccharide-deficient mutants of Rhizobium meliloti that form ineffective nodules
    • Leigh, J. A., E. R. Signer, and G. C. Walker. 1985. Exopolysaccharide-deficient mutants of Rhizobium meliloti that form ineffective nodules. Proc. Natl. Acad. Sci. USA 82:6231-6235.
    • (1985) Proc. Natl. Acad. Sci. USA , vol.82 , pp. 6231-6235
    • Leigh, J.A.1    Signer, E.R.2    Walker, G.C.3
  • 30
    • 0041110220 scopus 로고    scopus 로고
    • Expression and purification of four different rhizobial acyl carrier proteins
    • Lopez-Lara, I. M., and O. Geiger. 2000. Expression and purification of four different rhizobial acyl carrier proteins. Microbiology 146:839-849.
    • (2000) Microbiology , vol.146 , pp. 839-849
    • Lopez-Lara, I.M.1    Geiger, O.2
  • 31
    • 0034677968 scopus 로고    scopus 로고
    • The antiactivator TraM interferes with the autoinducer-dependent binding of TraR to DNA by interacting with the C-terminal region of the quorum-sensing activator
    • Luo, Z. Q., Y. Qin, and S. K. Farrand. 2000. The antiactivator TraM interferes with the autoinducer-dependent binding of TraR to DNA by interacting with the C-terminal region of the quorum-sensing activator. J. Biol. Chem. 275:7713-7722.
    • (2000) J. Biol. Chem. , vol.275 , pp. 7713-7722
    • Luo, Z.Q.1    Qin, Y.2    Farrand, S.K.3
  • 32
    • 0036285252 scopus 로고    scopus 로고
    • Identification of two quorum-sensing systems in Sinorhizobium meliloti
    • Marketon, M. M., and J. E. González. 2002. Identification of two quorum-sensing systems in Sinorhizobium meliloti. J. Bacteriol. 184:3466-3475.
    • (2002) J. Bacteriol. , vol.184 , pp. 3466-3475
    • Marketon, M.M.1    González, J.E.2
  • 34
    • 0034061824 scopus 로고    scopus 로고
    • Control of bioluminescence in Vibrio fischeri by the LuxO signal response regulator
    • Miyamoto, C. M., Y. H. Lin, and E. A. Meighen. 2000. Control of bioluminescence in Vibrio fischeri by the LuxO signal response regulator. Mol. Microbiol. 36:594-607.
    • (2000) Mol. Microbiol. , vol.36 , pp. 594-607
    • Miyamoto, C.M.1    Lin, Y.H.2    Meighen, E.A.3
  • 35
    • 0029980095 scopus 로고    scopus 로고
    • Enzymatic synthesis of a quorum-sensing autoinducer through use of defined substrates
    • More, M. I., L. D. Finger, J. L. Stryker, C. Fuqua, A. Eberhard, and S. C. Winans. 1996. Enzymatic synthesis of a quorum-sensing autoinducer through use of defined substrates. Science 272:1655-1658.
    • (1996) Science , vol.272 , pp. 1655-1658
    • More, M.I.1    Finger, L.D.2    Stryker, J.L.3    Fuqua, C.4    Eberhard, A.5    Winans, S.C.6
  • 36
    • 0027299747 scopus 로고
    • Expression of Pseudomonas aeruginosa virulence genes requires cell-to-cell communication
    • Passador, L., J. M. Cook, M. J. Gambello, L. Rust, and B. H. Iglewski. 1993. Expression of Pseudomonas aeruginosa virulence genes requires cell-to-cell communication. Science 260:1127-1130.
    • (1993) Science , vol.260 , pp. 1127-1130
    • Passador, L.1    Cook, J.M.2    Gambello, M.J.3    Rust, L.4    Iglewski, B.H.5
  • 37
    • 0027195161 scopus 로고
    • The presence of a novel type of surface polysaccharide in Rhizobium meliloti requires a new fatty acid synthase-like gene cluster involved in symbiotic nodule development
    • Petrovics, G., P. Putnoky, B. Reuhs, J. Kim, T. A. Thorp, K. D. Noel, R. W. Carlson, and A. Kondorosi. 1993. The presence of a novel type of surface polysaccharide in Rhizobium meliloti requires a new fatty acid synthase-like gene cluster involved in symbiotic nodule development. Mol. Microbiol. 8:1083-1094.
    • (1993) Mol. Microbiol. , vol.8 , pp. 1083-1094
    • Petrovics, G.1    Putnoky, P.2    Reuhs, B.3    Kim, J.4    Thorp, T.A.5    Noel, K.D.6    Carlson, R.W.7    Kondorosi, A.8
  • 38
    • 0030671073 scopus 로고    scopus 로고
    • A quorum-sensing system in the free-living photosynthetic bacterium Rhodobacter sphaeroides
    • Puskas, A., E. P. Greenberg, S. Kaplan, and A. L. Schaefer. 1997. A quorum-sensing system in the free-living photosynthetic bacterium Rhodobacter sphaeroides. J. Bacteriol. 179:7530-7537.
    • (1997) J. Bacteriol. , vol.179 , pp. 7530-7537
    • Puskas, A.1    Greenberg, E.P.2    Kaplan, S.3    Schaefer, A.L.4
  • 39
    • 0027158657 scopus 로고
    • Versatile suicide vectors which allow direct selection for gene replacement in gram-negative bacteria
    • Quandt, J., and M. F. Hynes. 1993. Versatile suicide vectors which allow direct selection for gene replacement in gram-negative bacteria. Gene 127: 15-21.
    • (1993) Gene , vol.127 , pp. 15-21
    • Quandt, J.1    Hynes, M.F.2
  • 40
    • 0026703235 scopus 로고
    • The gene encoding Escherichia coli acyl carrier protein lies within a cluster of fatty acid biosynthetic genes
    • Rawlings, M., and J. E. Cronan, Jr. 1992. The gene encoding Escherichia coli acyl carrier protein lies within a cluster of fatty acid biosynthetic genes. J. Biol. Chem. 267:5751-5754.
    • (1992) J. Biol. Chem. , vol.267 , pp. 5751-5754
    • Rawlings, M.1    Cronan J.E., Jr.2
  • 41
    • 0031906353 scopus 로고    scopus 로고
    • luxI- and luxR-homologous genes of Rhizobium etli CNPAF512 contribute to synthesis of autoinducer molecules and nodulation of Phaseolus vulgaris
    • Rosemeyer, V., J. Michiels, C. Verreth, and J. Vanderleyden. 1998. luxI- and luxR-homologous genes of Rhizobium etli CNPAF512 contribute to synthesis of autoinducer molecules and nodulation of Phaseolus vulgaris. J. Bacteriol. 180:815-821.
    • (1998) J. Bacteriol. , vol.180 , pp. 815-821
    • Rosemeyer, V.1    Michiels, J.2    Verreth, C.3    Vanderleyden, J.4
  • 42
    • 0033931441 scopus 로고    scopus 로고
    • Detection, purification, and structural elucidation of the acylhomoserine lactone inducer of Vibrio fisched luminescence and other related molecules
    • Schaefer, A. L., B. L. Hanzelka, M. R. Parsek, and E. P. Greenberg. 2000. Detection, purification, and structural elucidation of the acylhomoserine lactone inducer of Vibrio fisched luminescence and other related molecules. Methods Enzymol. 305:288-301.
    • (2000) Methods Enzymol. , vol.305 , pp. 288-301
    • Schaefer, A.L.1    Hanzelka, B.L.2    Parsek, M.R.3    Greenberg, E.P.4
  • 43
    • 0030071672 scopus 로고    scopus 로고
    • Bacteriocin small of Rhizobium leguminosarum belongs to the class of N-acyl-L-homoserine lactone molecules, known as autoinducers and as quorum sensing co-transcription factors
    • Schripsema, J., K. E. de Rudder, T. B. van Vliet, P. P. Lankhorst, E. de Vroom, J. W. Kijne, and A. A. van Brussel. 1996. Bacteriocin small of Rhizobium leguminosarum belongs to the class of N-acyl-L-homoserine lactone molecules, known as autoinducers and as quorum sensing co-transcription factors. J. Bacteriol. 178:366-371.
    • (1996) J. Bacteriol. , vol.178 , pp. 366-371
    • Schripsema, J.1    De Rudder, K.E.2    Van Vliet, T.B.3    Lankhorst, P.P.4    De Vroom, E.5    Kijne, J.W.6    Van Brussel, A.A.7
  • 44
    • 0027134384 scopus 로고
    • Small broad-host-range gentamycin resistance gene cassettes for site-specific insertion and deletion mutagenesis
    • Schweizer, H. D. 1993. Small broad-host-range gentamycin resistance gene cassettes for site-specific insertion and deletion mutagenesis. BioTechniques 15:831-834.
    • (1993) BioTechniques , vol.15 , pp. 831-834
    • Schweizer, H.D.1
  • 45
    • 0028967496 scopus 로고
    • Activation of the Pseudomonas aeruginosa lasI gene by LasR and the Pseudomonas autoinducer PAI: An autoinduction regulatory hierarchy
    • Seed, P. C., L. Passador, and B. H. Iglewski. 1995. Activation of the Pseudomonas aeruginosa lasI gene by LasR and the Pseudomonas autoinducer PAI: an autoinduction regulatory hierarchy. J. Bacteriol. 177:654-659.
    • (1995) J. Bacteriol. , vol.177 , pp. 654-659
    • Seed, P.C.1    Passador, L.2    Iglewski, B.H.3
  • 47
    • 0028598277 scopus 로고
    • Synergistic binding of the Vibrio fischeri LuxR transcriptional activator domain and RNA polymerase to the lux promoter region
    • Stevens, A. M., K. M. Dolan, and E. P. Greenberg. 1994. Synergistic binding of the Vibrio fischeri LuxR transcriptional activator domain and RNA polymerase to the lux promoter region. Proc. Natl. Acad. Sci. USA 91:12619-12623.
    • (1994) Proc. Natl. Acad. Sci. USA , vol.91 , pp. 12619-12623
    • Stevens, A.M.1    Dolan, K.M.2    Greenberg, E.P.3
  • 48
    • 0031033798 scopus 로고    scopus 로고
    • Quorum sensing in Vibrio fischeri: Essential elements for activation of the luminescence genes
    • Stevens, A. M., and E. P. Greenberg. 1997. Quorum sensing in Vibrio fischeri: essential elements for activation of the luminescence genes. J. Bacteriol. 179:557-562.
    • (1997) J. Bacteriol. , vol.179 , pp. 557-562
    • Stevens, A.M.1    Greenberg, E.P.2
  • 50
    • 0032873702 scopus 로고    scopus 로고
    • Structure of the Mesorhizobium huakuii and Rhizobium galegae Nod factors: A cluster of phylogenetically related legumes are nodulated by rhizobia producing Nod factors with α,β-unsaturated N-acyl substitutions
    • Yang, G. P., F. Debelle, A. Savagnac, M. Ferro, O. Schlitz, F. Maillet, D. Prome, M. Treilhou, C. Vialas, K. Lindstrom, J. Denarie, and J. C. Prome. 1999. Structure of the Mesorhizobium huakuii and Rhizobium galegae Nod factors: a cluster of phylogenetically related legumes are nodulated by rhizobia producing Nod factors with α,β-unsaturated N-acyl substitutions. Mol. Microbiol. 34:227-237.
    • (1999) Mol. Microbiol. , vol.34 , pp. 227-237
    • Yang, G.P.1    Debelle, F.2    Savagnac, A.3    Ferro, M.4    Schlitz, O.5    Maillet, F.6    Prome, D.7    Treilhou, M.8    Vialas, C.9    Lindstrom, K.10    Denarie, J.11    Prome, J.C.12


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.