Dataset Information

Indole-3-acetic acid synthesized through the indole-3-pyruvate pathway promotes Candida tropicalis biofilm formation.

ABSTRACT: We previously found that the elevated abundance of the fungus Candida tropicalis is positively correlated with the bacteria Escherichia coli and Serratia marcescens in Crohn's disease patients and the three pathogens, when co-cultured, form a robust mixed-species biofilm. The finding suggests that these three pathogens communicate and promote biofilm formation, possibly through secretion of small signaling molecules. To identify candidate signaling molecules, we carried out a metabolomic analysis of the single-species and triple-species cultures of the three pathogens. This analysis identified 15 metabolites that were highly increased in the triple-species culture. One highly induced metabolite was indole-3-acetic acid (IAA), which has been shown to induce filamentation of certain fungi. We thus tested the effect of IAA on biofilm formation of C. tropicalis and demonstrated that IAA promotes biofilm formation of C. tropicalis. Then, we carried out isotope tracing experiments using 13C-labeled-tryptophan as a precursor to uncover the biosynthesis pathway of IAA in C. tropicalis. The results indicated that C. tropicalis synthesizes IAA through the indole-3-pyruvate pathway. Further studies using inhibitors of the indole-3-pyruvate pathway are warranted to decipher the mechanisms by which IAA influences biofilm formation.

SUBMITTER: Miyagi M

PROVIDER: S-EPMC7746184 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Indole-3-acetic acid synthesized through the indole-3-pyruvate pathway promotes Candida tropicalis biofilm formation.

Miyagi Masaru M Wilson Rachel R Saigusa Daisuke D Umeda Keiko K Saijo Reina R Hager Christopher L CL Li Yuejin Y McCormick Thomas T Ghannoum Mahmoud A MA

PloS one 20201217 12

We previously found that the elevated abundance of the fungus Candida tropicalis is positively correlated with the bacteria Escherichia coli and Serratia marcescens in Crohn's disease patients and the three pathogens, when co-cultured, form a robust mixed-species biofilm. The finding suggests that these three pathogens communicate and promote biofilm formation, possibly through secretion of small signaling molecules. To identify candidate signaling molecules, we carried out a metabolomic analysi ...[more]

PMID: 33332404

Similar Datasets

Project description:Variovorax is a metabolically diverse genus of plant growth-promoting rhizobacteria (PGPR) that engages in mutually beneficial interactions between plants and microbes. Unlike most PGPR, Variovorax cannot synthesize the phytohormone indole-3-acetic acid (IAA) via tryptophan. However, we found that Variovorax boronicumulans strain CGMCC 4969 can produce IAA using indole-3-acetonitrile (IAN) as the precursor. Thus, in the present study, the IAA synthesis mechanism of V. boronicumulans CGMCC 4969 was investigated. V. boronicumulans CGMCC 4969 metabolized IAN to IAA through both a nitrilase-dependent pathway and a nitrile hydratase (NHase) and amidase-dependent pathway. Cobalt enhanced the metabolic flux via the NHase/amidase, by which IAN was rapidly converted to indole-3-acetamide (IAM) and in turn to IAA. IAN stimulated metabolic flux via the nitrilase, by which IAN was rapidly converted to IAA. Subsequently, the IAA was degraded. V. boronicumulans CGMCC 4969 can use IAN as the sole carbon and nitrogen source for growth. Genome sequencing confirmed the IAA synthesis pathways. Gene cloning and overexpression in Escherichia coli indicated that NitA has nitrilase activity and IamA has amidase activity to respectively transform IAN and IAM to IAA. Interestingly, NitA showed a close genetic relationship with the nitrilase of the phytopathogen Pseudomonas syringae Quantitative PCR analysis indicated that the NHase/amidase system is constitutively expressed, whereas the nitrilase is inducible. The present study helps our understanding of the versatile functions of Variovorax nitrile-converting enzymes that mediate IAA synthesis and the interactions between plants and these bacteria.IMPORTANCE We demonstrated that Variovorax boronicumulans CGMCC 4969 has two enzymatic systems-nitrilase and nitrile hydratase/amidase-that convert indole-3-acetonitrile (IAN) to the important plant hormone indole-3-acetic acid (IAA). The two IAA synthesis systems have very different regulatory mechanisms, affecting the IAA synthesis rate and duration. The nitrilase was induced by IAN, which was rapidly converted to IAA; subsequently, IAA was rapidly consumed for cell growth. The nitrile hydratase (NHase) and amidase system was constitutively expressed and slowly but continuously synthesized IAA. In addition to synthesizing IAA from IAN, CGMCC 4969 has a rapid IAA degradation system, which would be helpful for a host plant to eliminate redundant IAA. This study indicates that the plant growth-promoting rhizobacterium V. boronicumulans CGMCC 4969 has the potential to be used by host plants to regulate the IAA level.

Dataset Information

Indole-3-acetic acid synthesized through the indole-3-pyruvate pathway promotes Candida tropicalis biofilm formation.

Publications

Indole-3-acetic acid synthesized through the indole-3-pyruvate pathway promotes Candida tropicalis biofilm formation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets