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Koyanagi T, Nakagawa A, Sakurama H, Yamamoto K, Sakurai N, Takagi Y, Minami H, Katayama T, Kumagai H. Eukaryotic-type aromatic amino acid decarboxylase from the root colonizer Pseudomonas putida is highly specific for 3,4-dihydroxyphenyl-L-alanine, an allelochemical in the rhizosphere. MICROBIOLOGY-SGM 2012; 158:2965-2974. [PMID: 23059975 DOI: 10.1099/mic.0.062463-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Aromatic amino acid decarboxylases (AADCs) are found in various organisms and play distinct physiological roles. AADCs from higher eukaryotes have been well studied because they are involved in the synthesis of biologically important molecules such as neurotransmitters and alkaloids. In contrast, bacterial AADCs have received less attention because of their simplicity in physiology and in target substrate (tyrosine). In the present study, we found that Pseudomonas putida KT2440 possesses an AADC homologue (PP_2552) that is more closely related to eukaryotic enzymes than to bacterial enzymes, and determined the genetic and enzymic characteristics of the homologue. The purified enzyme converted 3,4-dihydroxyphenyl-l-alanine (DOPA) to dopamine with K(m) and k(cat) values of 0.092 mM and 1.8 s(-1), respectively. The enzyme was essentially inactive towards other aromatic amino acids such as 5-hydroxy-l-tryptophan, l-phenylalanine, l-tryptophan and l-tyrosine. The observed strict substrate specificity is distinct from that of any AADC characterized so far. The proposed name of this enzyme is DOPA decarboxylase (DDC). Expression of the gene was induced by DOPA, as revealed by quantitative RT-PCR analysis. DDC is encoded in a cluster together with a LysR-type transcriptional regulator and a major facilitator superfamily transporter. This genetic organization is conserved among all sequenced P. putida strains that inhabit the rhizosphere environment, where DOPA acts as a strong allelochemical. These findings suggest the possible involvement of this enzyme in detoxification of the allelochemical in the rhizosphere, and the potential occurrence of a horizontal gene transfer event between the pseudomonad and its host organism.
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Affiliation(s)
- Takashi Koyanagi
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Akira Nakagawa
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Haruko Sakurama
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Keiko Yamamoto
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Naofumi Sakurai
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Yukinobu Takagi
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Hiromichi Minami
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Takane Katayama
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Hidehiko Kumagai
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
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van Bruggen AHC, Semenov AM, Zelenev VV, Semenov AV, Raaijmakers JM, Sayler RJ, de Vos O. Wave-like distribution patterns of gfp-marked Pseudomonas fluorescens along roots of wheat plants grown in two soils. MICROBIAL ECOLOGY 2008; 55:466-475. [PMID: 17934689 DOI: 10.1007/s00248-007-9292-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 05/06/2007] [Accepted: 06/18/2007] [Indexed: 05/25/2023]
Abstract
Culturable rhizosphere bacterial communities had been shown to exhibit wave-like distribution patterns along wheat roots. In the current work we show, for the first time, significant wave-like oscillations of an individual bacterial strain, the biocontrol agent Pseudomonas fluorescens 32 marked with gfp, along 3-week-old wheat roots in a conventionally managed and an organically managed soil. Significant wave-like fluctuations were observed for colony forming units (CFUs) on selective media and direct fluorescent counts under the microscope. Densities of fluorescent cells and of CFUs fluctuated in a similar manner along wheat roots in the conventional soil. The frequencies of the first, second, and third harmonics were similar for direct cell counts and CFUs. Survival of P. fluorescens 32-gfp introduced into organically managed soil was lower than that of the same strain added to conventionally managed soil. Thus, when root tips reached a depth of 10-35 cm below soil level, the majority of the introduced cells may have died, so that no cells or CFU"s were detected in this region at the time of sampling. As a result, significant waves in CFUs or direct counts along roots were not found in organically managed soil, except when a sufficiently long series with detectable CFUs were obtained. In this last case the wave-like fluctuation in CFUs was damped toward the root tip. In conclusion, when cells of a single bacterial strain randomly mixed in soil survived until a root tip passed, growth and death cycles after passage of the root tip resulted in oscillating patterns of population densities of this strain along 3-week-old wheat roots.
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Affiliation(s)
- Ariena H C van Bruggen
- Department of Plant Sciences, Biological Farming Systems Group, Wageningen University and Research Centre, Wageningen, The Netherlands.
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Cardon ZG, Gage DJ. Resource Exchange in the Rhizosphere: Molecular Tools and the Microbial Perspective. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2006. [DOI: 10.1146/annurev.ecolsys.37.091305.110207] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Zoe G. Cardon
- Department of Ecology and Evolutionary Biology and Center for Integrative Geosciences, University of Connecticut, Storrs, Connecticut 06269;
| | - Daniel J. Gage
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269;
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