Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic Analyses

Acidovorax citrulli (Ac) is a Gram-negative phytopathogenic bacterium causing bacterial fruit blotch (BFB) on cucurbit crops, specifically in the watermelon industry. However, cultivars of watermelon that are resistant to Ac have not been identified. Therefore, virulence factors/mechanisms in Ac mus...

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Main Authors: Yongmin Cho, Haerim Rhyu, Suhyun Lee, Dohyun Kim, Dae Sung Kim, Jisun H. J. Lee, Sang-Wook Han
Format: Article
Language:English
Published: Hanrimwon Publishing Company 2025-06-01
Series:The Plant Pathology Journal
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Online Access:http://ppjonline.org/upload/pdf/PPJ-OA-03-2025-0036.pdf
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author Yongmin Cho
Haerim Rhyu
Suhyun Lee
Dohyun Kim
Dae Sung Kim
Jisun H. J. Lee
Sang-Wook Han
author_facet Yongmin Cho
Haerim Rhyu
Suhyun Lee
Dohyun Kim
Dae Sung Kim
Jisun H. J. Lee
Sang-Wook Han
author_sort Yongmin Cho
collection DOAJ
description Acidovorax citrulli (Ac) is a Gram-negative phytopathogenic bacterium causing bacterial fruit blotch (BFB) on cucurbit crops, specifically in the watermelon industry. However, cultivars of watermelon that are resistant to Ac have not been identified. Therefore, virulence factors/mechanisms in Ac must be characterized to develop alternative control strategies. Functions of a histidinol dehydrogenase, which is an essential enzyme for histidine biosynthesis, remain elusive in Ac. This study aims to elucidate the roles of histidinol dehydrogenase in Ac (HisDAc) using phenotype assays and proteomic analysis. The virulence of a mutant lacking a histidinol dehydrogenase, hisDAc:Tn5(EV), was diminished in geminated-seed inoculation and leaf infiltration assays, and the bacterium was impossible to grow without histidine in minimal media. However, treatment with exogenous histidine completely restored the virulence of the mutant on watermelon and its growth in minimal media, demonstrating that HisDAc is required for histidine biosynthesis, which contributes to virulence and growth. The comparative proteomic analysis indicates that HisDAc is involved in not only amino acid metabolism but also other biological mechanisms, including cell wall/membrane/envelope functions. This suggests that HisDAc may have pleiotropic effects. It was also confirmed that when Escherichia coli was incubated with Ac strains in water, the population level of E. coli increased in the presence of the mutant but not in the presence of the wild-type. This study leads to new insights regarding enzymes related to the production of primary metabolites and provides a promising target to discover an anti-virulence reagent to control BFB.
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id doaj-art-065b2e51f10c4770b2b934c843a4b43e
institution Kabale University
issn 1598-2254
2093-9280
language English
publishDate 2025-06-01
publisher Hanrimwon Publishing Company
record_format Article
series The Plant Pathology Journal
spelling doaj-art-065b2e51f10c4770b2b934c843a4b43e2025-08-20T03:45:47ZengHanrimwon Publishing CompanyThe Plant Pathology Journal1598-22542093-92802025-06-0141334135110.5423/PPJ.OA.03.2025.00362516Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic AnalysesYongmin Cho0Haerim Rhyu1Suhyun Lee2Dohyun Kim3Dae Sung Kim4Jisun H. J. Lee5Sang-Wook Han6 Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, Korea Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, Korea Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, Korea Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, Korea State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 430062, China Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, Korea Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, KoreaAcidovorax citrulli (Ac) is a Gram-negative phytopathogenic bacterium causing bacterial fruit blotch (BFB) on cucurbit crops, specifically in the watermelon industry. However, cultivars of watermelon that are resistant to Ac have not been identified. Therefore, virulence factors/mechanisms in Ac must be characterized to develop alternative control strategies. Functions of a histidinol dehydrogenase, which is an essential enzyme for histidine biosynthesis, remain elusive in Ac. This study aims to elucidate the roles of histidinol dehydrogenase in Ac (HisDAc) using phenotype assays and proteomic analysis. The virulence of a mutant lacking a histidinol dehydrogenase, hisDAc:Tn5(EV), was diminished in geminated-seed inoculation and leaf infiltration assays, and the bacterium was impossible to grow without histidine in minimal media. However, treatment with exogenous histidine completely restored the virulence of the mutant on watermelon and its growth in minimal media, demonstrating that HisDAc is required for histidine biosynthesis, which contributes to virulence and growth. The comparative proteomic analysis indicates that HisDAc is involved in not only amino acid metabolism but also other biological mechanisms, including cell wall/membrane/envelope functions. This suggests that HisDAc may have pleiotropic effects. It was also confirmed that when Escherichia coli was incubated with Ac strains in water, the population level of E. coli increased in the presence of the mutant but not in the presence of the wild-type. This study leads to new insights regarding enzymes related to the production of primary metabolites and provides a promising target to discover an anti-virulence reagent to control BFB.http://ppjonline.org/upload/pdf/PPJ-OA-03-2025-0036.pdfacidovorax citrullibacterial fruit blotchhistidinol dehydrogenase
spellingShingle Yongmin Cho
Haerim Rhyu
Suhyun Lee
Dohyun Kim
Dae Sung Kim
Jisun H. J. Lee
Sang-Wook Han
Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic Analyses
The Plant Pathology Journal
acidovorax citrulli
bacterial fruit blotch
histidinol dehydrogenase
title Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic Analyses
title_full Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic Analyses
title_fullStr Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic Analyses
title_full_unstemmed Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic Analyses
title_short Deciphering Functions of a Putative Histidinol Dehydrogenase in Acidovorax citrulli by Phenotypic and Proteomic Analyses
title_sort deciphering functions of a putative histidinol dehydrogenase in acidovorax citrulli by phenotypic and proteomic analyses
topic acidovorax citrulli
bacterial fruit blotch
histidinol dehydrogenase
url http://ppjonline.org/upload/pdf/PPJ-OA-03-2025-0036.pdf
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