The Steroid Catabolic Pathway of the Intracellular Pathogen Rhodococcus equi Is Important for Pathogenesis and a Target for Vaccine Development

Geize, Robert van der; Grommen, A. W. F.; Hessels, G.I.; Jacobs, A. A. C.; Dijkhuizen, Lubbert

doi:10.1371/journal.ppat.1002181

Cited by 73 publications

(67 citation statements)

References 61 publications

(84 reference statements)

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“…The results of this study suggest that the cholesterol and cholate catabolic pathways in Rhodococcus spp. converge on a common route for degradation of steroid rings C and D. Previously, a cluster of genes in R. equi was implicated in degradation of 3a␣-H-4␣(3=-propanoate)-7a␤-methylhexahydro-1,5-indanedione (HIP), a cholesterol degradation intermediate containing rings C and D (30). Within this cluster, ipdA and ipdB encode a heterodimeric CoA transferase proposed to initiate beta-oxidation of the propanoyl moiety of HIP.…”

Section: Discussionmentioning

confidence: 99%

Gene Cluster Encoding Cholate Catabolism in Rhodococcus spp

et al. 2012

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bBile acids are highly abundant steroids with important functions in vertebrate digestion. Their catabolism by bacteria is an important component of the carbon cycle, contributes to gut ecology, and has potential commercial applications. We found that Rhodococcus jostii RHA1 grows well on cholate, as well as on its conjugates, taurocholate and glycocholate. The transcriptome of RHA1 growing on cholate revealed 39 genes upregulated on cholate, occurring in a single gene cluster. Reverse transcriptase quantitative PCR confirmed that selected genes in the cluster were upregulated 10-fold on cholate versus on cholesterol. One of these genes, kshA3, encoding a putative 3-ketosteroid-9␣-hydroxylase, was deleted and found essential for growth on cholate. Two coenzyme A (CoA) synthetases encoded in the cluster, CasG and CasI, were heterologously expressed. CasG was shown to transform cholate to cholyl-CoA, thus initiating side chain degradation. CasI was shown to form CoA derivatives of steroids with isopropanoyl side chains, likely occurring as degradation intermediates. Orthologous gene clusters were identified in all available Rhodococcus genomes, as well as that of Thermomonospora curvata. Moreover, Rhodococcus equi 103S, Rhodococcus ruber Chol-4 and Rhodococcus erythropolis SQ1 each grew on cholate. In contrast, several mycolic acid bacteria lacking the gene cluster were unable to grow on cholate. Our results demonstrate that the above-mentioned gene cluster encodes cholate catabolism and is distinct from a more widely occurring gene cluster encoding cholesterol catabolism. Bile salts are surface-active steroids with an important role in the uptake and metabolism of lipophilic substrates in vertebrates. These steroids, which include cholate and chenodeoxycholate, are synthesized in the liver from cholesterol, and their eventual fate is excretion in feces or urine. Bile salts may be modified, either by microbiological activity in the duodenum or by host cell bioactivity, leading to their conjugation to glycine, taurine, or sulfate. As such, biodegradation of the various bile salts is a significant process in carbon cycling in soil and aquatic environments. The processes involved in microbial transformation of steroids are also relevant for biotechnological applications in the synthesis and/or selective modification of steroid-based drugs (29).Despite the cytotoxicity of cholate toward various prokaryotic and eukaryotic cells, several bacterial species, especially members of the Proteobacteria (27, 28) and Actinomycetales (9, 32), are able to efficiently metabolize this substrate to sustain growth. Recent studies on microbial bile salts degradation have focused on the Proteobacteria. Genes encoding several steps in cholate degradation were identified, mainly in Comamonas testosteroni TA441 and Pseudomonas sp. strain Chol1. In the former strain, genes responsible for oxidation of the steroid nucleus were found (10-13), while in the latter, genes responsible for degradation of the cholate side chain were identified, in...

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Section: Discussionmentioning

confidence: 99%

Gene Cluster Encoding Cholate Catabolism in Rhodococcus spp

et al. 2012

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“…The information presented here may allow manipulating the catalytic properties of the enzyme to improve it for application in the pharmaceutical steroid industry. Furthermore, the steroid catabolic activity of steroid-degrading pathogenic bacteria such as Mycobacterium tuberculosis and Rhodococcus equi is frequently associated with their pathogenicity (18,19). In particular, cholesterol degradation appeared to be essential for the survival of M. tuberculosis in the normally adverse environment of the host macrophages (19,20).…”

Section: -Ketosteroid ⌬mentioning

confidence: 99%

Crystal Structure and Site-directed Mutagenesis of 3-Ketosteroid Δ1-Dehydrogenase from Rhodococcus erythropolis SQ1 Explain Its Catalytic Mechanism

Rohman

Oosterwijk

Thunnissen

et al. 2013

Journal of Biological Chemistry

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Background: 3-Ketosteroid ⌬ 1 -dehydrogenases catalyze the 1,2-desaturation of 3-ketosteroids. Results: First structures of the enzyme from Rhodococcus erythropolis SQ1, combined with site-directed mutagenesis, clarify its catalytic mechanism. Conclusion: Tyr 487 and Gly 491 promote keto-enol tautomerization, whereas Tyr 318 /Tyr 119 and FAD abstract a proton and hydride ion, respectively. Significance: This study is an important step toward tailoring the enzyme for steroid biotransformation applications.

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“…1B), including fadD3 and ipdAB. IpdAB is required for virulence in Rhodococcus equi and an ipdAB deletion strain has been patented as a live vaccine (13,15). KstR2 binds to three ϳ14-bp inverted palindromic operator sequences, or KstR2 boxes, located at the intergenic regions of the regulon (13).…”

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confidence: 99%